Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Power metallurgical technique.
Artykuły w czasopismach na temat „Power metallurgical technique”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych artykułów w czasopismach naukowych na temat „Power metallurgical technique”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj artykuły w czasopismach z różnych dziedzin i twórz odpowiednie bibliografie.
1
Kalyankar, Vivek D., i Hardik V. Naik. "Overview of metallurgical studies on weld deposited surface by plasma transferred arc technique". Metallurgical Research & Technology 118, nr 1 (2021): 111. http://dx.doi.org/10.1051/metal/2020088.
Pełny tekst źródłaStreszczenie:
Research on plasma transferred arc (PTA) coatings has increased contemplation due to its augmented appropriateness which results from the advanced materials used in applications like mining, petroleum and power plant sectors. This article further broadens the research scope of investigation, by influencing metallurgical and processing aspects in accordance with the significance of microstructural changes. Martensitic formation with coarser structure, carbide phase formation and fine interdendritic eutectic matrix are the significant metallurgical aspects for an improved surface characteristic. Welding current, powder feed rate and travel speed, are the significant processing variables to achieve the microstructural changes like uniform dendritic growth, finer grain size, etc. The addition of alloying elements and heat treatment are the most observed processing conditions for the formation of precipitates and carbide phases. A schematic summary, the significance of processing variables, processing conditions and process modelling and simulation on metallurgical aspects have been enumerated in this paper. Further, critical comments and findings from in-depth review have also been discussed for the future scope. Hence, this review will be helpful to ascertain the relation among the microstructural evolution, the applicability of microscopic tools and the mechanical properties for the forthcoming researchers and the industrial persons.
2
Ding, Chun, Ge Yan Fu i Shi Hong Shi. "Research on Process in Laser Cladding of Width-Changing Single Layer Based on Coaxial Inside-Beam Powder Feeding". Applied Mechanics and Materials 574 (lipiec 2014): 347–52. http://dx.doi.org/10.4028/www.scientific.net/amm.574.347.
Pełny tekst źródłaStreszczenie:
In this paper, coaxial inside-beam powder feeding technique was used. According to theoretical analysis and the single layer cladding experiments, the initial parameters and experimental scheme of width-changing layer cladding based on the coaxial inside-beam powder feeding were confirmed. The theory model of piecewise transition was established. The real-time control of scanning speed and the defocus amount to carry out the experiments were used while the laser power and powder feed rate were not changed. Finally, the layers with uniformly width changing and stable layer height were achieved. Performance analysis showed that the formed layer had smooth surface and a high rigidity without powder paste outside the surface, and the size was basically as same as the design value. Its microstructure was small and dense and good metallurgical combination was formed between part and substrate.
3
Lyman, Charles. "Small, Focused Technical Conferences". Microscopy Today 18, nr 2 (marzec 2010): 5. http://dx.doi.org/10.1017/s1551929510000210.
Pełny tekst źródłaStreszczenie:
The feature article in this issue is a prelude to the Microbeam Analysis Society (MAS) Topical Conference on electron backscatter diffraction (EBSD) to be held at the University of Wisconsin, May 24–26, 2010. The popularity of the EBSD technique is growing rapidly. This analytical method is capable of both identifying crystalline phases and determining the orientation of grains and second phases. Phase analysis by EBSD combined with elemental analysis by x-ray emission spectrometry provides the SEM with extraordinary analytical power. Maps of crystal grain orientations are widely used in metallurgical and geological research.
4
Kováčik, Jaroslav, Liviu Marsavina i Emanoil Linul. "Poisson’s Ratio of Closed-Cell Aluminium Foams". Materials 11, nr 10 (7.10.2018): 1904. http://dx.doi.org/10.3390/ma11101904.
Pełny tekst źródłaStreszczenie:
A nondestructive impulse excitation technique was used to investigate Poisson’s ratio of powder metallurgical pure closed-cell aluminium foams according to ASTM E 1876 within the foam density range of 0.430–1.390 g·cm−3. Instead of a constant value of 0.34, as according to Gibson and Ashby’s assumption for the Poisson’s ratio of metallic foams, the decrease of the Poisson’s ratio with decreasing foam density was observed. Observed Poisson’s ratio data were in the range of 0.21–0.34. To check the validity of the results, the Young’s modulus was calculated using Poisson’s ratio and its dependence on relative density was successfully modelled using the usual power law function with characteristic exponent of 1.72 ± 0.1. This confirms that the obtained experimental results for Poisson’s ratio are valid. Finally, rule of mixture and percolation theory were used to model the observed decrease of Poisson’s ratio with increasing porosity.
5
Lekakh, Simon N., i Jingjing Qing. "Engineering Heterogeneous Nucleation during Solidification of Multiphase Cast Alloys: An Overview". Metals 13, nr 7 (21.06.2023): 1154. http://dx.doi.org/10.3390/met13071154.
Pełny tekst źródłaStreszczenie:
The theory of heterogeneous nucleation was initially developed as a part of condensed matter physics, and later it was used as an important engineering tool to design metallurgical processes. This success has led to wide applications of the theory in metallurgical practice. For example, engineering heterogeneous nucleation in ductile iron has been used to reduce shrinkage defects, suppress cementite formation, and modify the size and shape of microstructural constituencies. This demonstrates how theoretical knowledge could benefit industry practice. This overview aims to summarize the authors’ published studies in co-authorship with colleagues and students, which covers different aspects of engineering heterogeneous nucleation in multiphase cast alloys. Several approaches for engineering heterogeneous nucleation using thermodynamic simulation as well as practical methods for improving efficiency of nucleation using the co-precipitation technique and a local transient melt supersaturation are suggested. Automated scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) analysis and high-resolution transmission electron microscopy (TEM) were used to verify the simulation predictions. Practical examples of controlling microporosity shrinkage in cast irons with spheroidal graphite are presented to illustrate the power of engineering heterogenous nucleation.
6
Mulhi, Ali, Shirin Dehgahi, Prashant Waghmare i Ahmed J. Qureshi. "Process Parameter Optimization of 2507 Super Duplex Stainless Steel Additively Manufactured by the Laser Powder Bed Fusion Technique". Metals 13, nr 4 (7.04.2023): 725. http://dx.doi.org/10.3390/met13040725.
Pełny tekst źródłaStreszczenie:
Laser powder bed fusion is an attractive technology for producing high-strength stainless steel alloys. Among the stainless steels, 2507 super duplex stainless steel (2507 SDSS) is known for its excellent combination of corrosion resistance and high strength. Although there are some studies that aimed at optimizing the laser powder bed fusion (LPBF) printing parameters to print highly dense 2507 SDSS parts; However, a full optimization study is not reported yet. This study aims at optimizing the printing parameters for 2507 SDSS, namely: laser power, scan speed, and hatch distance. The response surface methodology was used in generating a detailed design of experiment to investigate the different pore formation types over a wide energy density range (22.22–428.87 J/mm3), examine the effects of each process parameter and their interactions on the resulting porosity, and identify an optimized parameter set for producing highly dense parts. Different process parameters showed different pore formation mechanisms, with lack-of-fusion, metallurgical or gas, and keyhole regimes being the most prevalent pore types identified. The lack-of-fusion pores are observed to decrease significantly with increasing the energy density at low values. However, a gradual increase in the keyhole pores was observed at higher energy densities. An optimal energy density process window from 68.24 to 126.67 J/mm3 is identified for manufacturing highly dense (≥99.6%) 2507 SDSS parts. Furthermore, an optimized printing parameter set at a laser power of 217.4 W, a scan speed of 1735.7 mm/s, and a hatch distance of 51.3 µm was identified, which was able to produce samples with 99.961% relative density. Using the optimized parameter set, the as-built 2507 SDSS sample had a ferrite phase fraction of 89.3% with a yield and ultimate tensile strength of 1115.4 ± 120.7 MPa and 1256.7 ± 181.9 MPa, respectively.
7
Sukharev, D. Yu. "Assessment of efficiency improvement reserves of maintenance and repair systems of high-voltage electrical equipment of industrial enterprises". Russian Journal of Industrial Economics 16, nr 2 (13.06.2023): 62–72. http://dx.doi.org/10.17073/2072-1633-2023-2-190-200.
Pełny tekst źródłaStreszczenie:
The problems of choosing a strategy for the maintenance of the equipment of the power supply system of an industrial enterprise, taking into account the risk its failure and the problem of distributing the volume of the repair program in order to reduce maintenance costs and, accordingly, the cost of production, are considered. A method for assessing the magnitude of risk for the technological process of an industrial enterprise of the metallurgical industry, taking into account the power supply scheme of the electric receiver, is proposed. Special attention is paid to taking into account the influence of the power supply system of an industrial enterprise on the operation of final electrical receivers directly involved in the technological process. An example of using the proposed technique in a real power supply system with available statistical data on its failures is considered. The article formulates an approach to assessing the risk of failure of elements of the power supply network of an industrial enterprise, taking into account the operational scheme of power supply, and also shows the insufficiency of assessing the risk of power supply failures only from the failure of circuit elements through which electric power is directly transmitted to the electric receiver in question.
8
Cheepu, Muralimohan, D. Venkateswarlu, P. Nageswara Rao, S. Senthil Kumaran i Narayanan Srinivasan. "Effect of Process Parameters and Heat Input on Weld Bead Geometry of Laser Welded Titanium Ti-6Al-4V Alloy". Materials Science Forum 969 (sierpień 2019): 613–18. http://dx.doi.org/10.4028/www.scientific.net/msf.969.613.
Pełny tekst źródłaStreszczenie:
Laser beam welding is one of the most favorable welding technique and its importance in industry is demanding due to higher welding speeds and lower dimensions and distortions in the welds. Moreover, its high strength to weld geometries and minimal heat affected zones makes favorable for various industrial applications. In the present study, laser welding of titanium alloy was investigated to observe the effects of parameters on the bead geometry and metallurgical properties. The laser power and welding speeds were varied to identify their impact on the formation of weld geometry. The width and depth of the fusion zone is varied with welding conditions. The finer grains identified in weld zone and the width of heat affected zone was significantly changes with laser welding power. The mechanical properties of the weld joint are controlled by obtaining optimum weld bead geometry and width of the head affected zone in the welds.
9
Mazurkiewicz, Andrzej, i Andrzej Poprzeczka. "Evaluation of the quality of layers applied by LDT laser metal deposition". AUTOBUSY – Technika, Eksploatacja, Systemy Transportowe 19, nr 6 (30.06.2018): 591–96. http://dx.doi.org/10.24136/atest.2018.140.
Pełny tekst źródłaStreszczenie:
The article presents the results of a study of C45 carbon steel hardfacing using laser metal deposition with Stellit Co-21 powder. The microstructure of the cross-section of samples prepared with different scanning speed and the amount of used powder at constant laser power was observed. Analyzing the cross-sectional areas of the samples, it was found that, at specific production parameters, cracks occur in weld overlay, which should be associated with the amount of heat supplied and discharged, especially at the unheated basis.This may be confirmed by the presence of deposits of weakly branched dendrites in the microstructure, which should be related to the directional heat dissipation process and rapid directional crystallization. It is possible to regulate these phenomena by selecting appropriate processing parameters. The microstructure analysis of cross-sectional areas of samples after hardfacing using LDT technique indicates good metallurgical quality of the deposit with a small heat affected zone of about 660÷760m. The microhardness measurements on the sample cross-sections indicated a wide micohardness distribution ranging from 510HV1 in the weld overlay, about 410HV1 in the heat affected zone, to 270HV1 in the C45 steel base.
10
Yang, Yu Ling, Wei Yan, Duo Zhang, Gen Zong Song i Yi Ran Zheng. "In Situ-Fabrication of TiCN Ceramic Coating on Titanium Alloy by Laser Cladding Technology". Key Engineering Materials 434-435 (marzec 2010): 485–88. http://dx.doi.org/10.4028/www.scientific.net/kem.434-435.485.
Pełny tekst źródłaStreszczenie:
The insitu-fabrication of TiCN ceramic coating by laser cladding-laser nitriding technique (LC-LN) was investigated. Pulsed YAG laser with the power of 500W was used as radiation source. Highly pure N2 was selected as the nitriding element; Titanium powder whose size is 20 m and the pure carbon powder were utilized as the coating materials. The influence of technology parameters such as pulse width, pulse frequency and scanning speed etc. on the insitu-formation of TiCN ceramic coating was studied. XRD results show that the main phases of the coating are TiC0.3N0.7 (or TiC0.2N0.8),TiN and TiN0.3. It was revealed that the appropriate process parameters for insitu-fabrication are the pulse frequency 15 Hz, pulse width 3.0ms, the scanning speed in the range of 9cm/min to 12cm/min, the pressure of N2 0.4MPa. The result of OM showed a metallurgical bonding without crack and bubble between the coating and the substrate was obtained. The microstructure of cladded coating is characterized by fine dentrites. The average microhardness in the coating is more than 1300HV which is about 4 times of that in the substrate.
11
Kim, David Young. "Points on a Field: Gentile da Fabriano and Gold Ground". Journal of Early Modern History 23, nr 2-3 (28.05.2019): 191–226. http://dx.doi.org/10.1163/15700658-12342636.
Pełny tekst źródłaStreszczenie:
Abstract This essay considers gold grounds in early Renaissance panel painting as sites of the possible, here understood in the word’s double meaning as artistic power and mimetic potential. After examining how gold ground in art historiography is depicted as a zone oscillating between worldliness and otherworldliness, the discussion focuses on the process and meaning of gold ground in Cennino Cennini’s Libro dell’arte (c. 1390) and Gentile da Fabriano’s Virgin and Child (c. 1405, Perugia, Galleria Nazionale dell’umbria), with focus placed on the technique of granulation (opus punctorium). Also explored is how gold money and gold pictures exist in a relationship of exchange and mutual reinforcement, both depending on the faculty of sight to recognize them as bearers of value. Gold ground unfolds a spectrum of material, medial, perceptual, and devotional possibilities, which facilitates continuous passage between worlds, artisanal and climatic, pictorial and metallurgical, physical and ethereal.
12
Peng, Zhixin, Wei Xu, Yang Liu, Kai Zhao i Ping Hu. "Anisotropy Evaluation and Defect Detection on Laser Power Bed Fusion 316L Stainless Steel". Micromachines 14, nr 6 (7.06.2023): 1206. http://dx.doi.org/10.3390/mi14061206.
Pełny tekst źródłaStreszczenie:
Because of rapid heating, cooling, and solidification during metal additive manufacturing (AM), the resulting products exhibit strong anisotropy and are at risk of quality problems from metallurgical defects. The defects and anisotropy affect the fatigue resistance and material properties, including mechanical, electrical, and magnetic properties, which limit the applications of the additively manufactured components in the field of engineering. In this study, the anisotropy of laser power bed fusion 316L stainless steel components was first measured by conventional destructive approaches using metallographic methods, X-ray diffraction (XRD), and electron backscatter diffraction (EBSD). Then, anisotropy was also evaluated by ultrasonic nondestructive characterization using the wave speed, attenuation, and diffuse backscatter results. The results from the destructive and nondestructive methods were compared. The wave speed fluctuated in a small range, while the attenuation and diffuse backscatter results were varied depending on the build direction. Furthermore, a laser power bed fusion 316L stainless steel sample with a series of artificial defects along the build direction was investigated via laser ultrasonic testing, which is more commonly used for AM defect detection. The corresponding ultrasonic imaging was improved with the synthetic aperture focusing technique (SAFT), which was found to be in good agreement with the results from the digital radiograph (DR). The outcomes of this study provide additional information for anisotropy evaluation and defect detection for improving the quality of additively manufactured products.
13
Kayode, Oyindamola, i Esther Titilayo Akinlabi. "Investigation of microstructural and mechanical properties of AA1050-AZ91D dissimilar friction stir welding". Journal of Mechanical Engineering and Sciences 15, nr 3 (19.09.2021): 8332–43. http://dx.doi.org/10.15282/jmes.15.3.2021.11.0655.
Pełny tekst źródłaStreszczenie:
Joining of aluminium and magnesium alloys frequently pose significant challenges to the extent where joining may seem impossible, due to differences in the physical, metallurgical, and chemical properties of the materials. Friction stir welding is a solid-state welding technique which uses a non-consumable tool to join metals. This study examines the dissimilar friction stir welding of 3 mm thick AA1050 and AZ91D alloy sheets. Successful defect-free joints were achieved at rotational speeds of 400 rpm and 600 rpm, and a constant traverse speed of 50 mm/min. The metallurgical investigations used to characterize the microstructure of the welds are optical microscopy (OM), scanning electron microscope (SEM) and X-ray diffraction (XRD). The microstructures of the samples show distinct morphology attributed to their different rotational speeds. However, Al3Mg2 intermetallics (IMCs) phase was detected in the white bands present in both weld samples. The IMCs were formed through solid-state diffusion. The mechanical properties characterizations includes the microhardness profiles and tensile testing. The variation in the rotational speeds do not have a significant effect on the microhardness distribution of the weld samples. The tensile strength of the dissimilar weld improved substantially with the presence of an interpenetration feature (IPF).
14
Ouallam, Seddik, J. E. Masse, P. Peyre, M. L. Djeghlal, F. Guittonneau, Z. Boutaghou i L. Kaba. "Microstructural and Mechanical Characterization of the Yb: YAG Laser Welding of High-Pressure Die-Casting Mg-Al-Mn Magnesium Alloy". International Journal of Engineering Research in Africa 51 (listopad 2020): 95–109. http://dx.doi.org/10.4028/www.scientific.net/jera.51.95.
Pełny tekst źródłaStreszczenie:
In this work, the Yb:YAG laser beam welding of the magnesium alloy AM60 was studied. A laser power of 2 kW and a welding speed of 3.5 m / min give a different welding quality than that obtained by CO2 laser with the same parameters. The metallurgical characterization, by optical microscopy, showed the formation of four distinct zones : base metal (BM), heat affected zone (HAZ), the partially fusion zone (PFZ) and the fusion zone (FZ), due to the thermal effect produced by the laser welding thermal cycle. Their dimensions are quantified. The microstructural examination using scanning electron microscopy showed the presence of fine dendritic structure in the FZ although the use of electron dispersive spectroscopy analysis confirm that an eutectic Mg17Al12 phase are surrounded by α-Mg solid solution in the HAZ. Electron backscattered diffraction technique revealed an important grain refinement in FZ and considerable twining phenomena in HAZ, but no texture. X-ray diffraction technique has been used, full width at half maximum of diffraction peaks is measured; it also confirmed the grain refinement in FZ in comparison to BM and HAZ. Both microhardness and tensile proprieties of the complete weld joint are similar to those of the BM.
15
Daleo, J. A., K. A. Ellison i D. A. Woodford. "Application of Stress Relaxation Testing in Metallurgical Life Assessment Evaluations of GTD111 Alloy Turbine Buckets". Journal of Engineering for Gas Turbines and Power 121, nr 1 (1.01.1999): 129–37. http://dx.doi.org/10.1115/1.2816299.
Pełny tekst źródłaStreszczenie:
Stress relaxation and constant displacement rate tensile tests were performed on polycrystalline GTD111 alloy material removed from General Electric MS6001B first stage combustion turbine buckets. Samples were examined in the standard heat treated condition, thermally exposed at 900°C for 5000 hours and from service run buckets. Creep rates of the material were measured and evaluated directly in terms of temperature capability at 850°C and 900°C. Stress relaxation tests done at 0.8 percent total strain indicated that the creep rate properties in the service exposed airfoil were an order of magnitude higher than the material properties in the standard heat treated condition measured in the root form. In terms of temperature capability, the creep rate properties of the service run airfoil material had decreased by the equivalent of almost 40°C. The Stress relaxation test method was demonstrated to be a very useful tool in quantifying the degradation of creep properties in service run components. Creep data that would require years to gather using conventional creep tests was generated in a few days. This now makes realistic life assessment and repair/replace decisions possible during turbine overhauls. The test method’s unique ability to measure changes in creep rate over a large stress range, enabled the technique to distinguish between changes in creep strength due to (normal) microstructural evolution from the combined effects of microstructural evolution and strain related creep damage. A method for estimating standard constant load creep rupture life from the stress relaxation creep rate data is also presented along with time-temperature parameter correlations. The data sets examined in this study indicate that creep rupture lives can be estimated within a factor of three from the stress relaxation data. The information and analysis techniques described in this paper are directly applicable to metallurgical life assessment evaluations and the requalification of repaired General Electric buckets in Frame 3, 5, 6, 7, and 9 engine models.
16
Zhang, Qunli, Yiyun Chen, Bo Li, Changyi Wang, Lijuan Wu i Jianhua Yao. "Tribological Behavior of Ti-Coated Diamond/Copper Composite Coating Fabricated via Supersonic Laser Deposition". Lubricants 11, nr 5 (11.05.2023): 216. http://dx.doi.org/10.3390/lubricants11050216.
Pełny tekst źródłaStreszczenie:
Diamond/copper composite coating is promising for wear-resistant applications, owing to the extreme hardness of the diamond reinforcement. Ti-coated diamond/copper composite coatings with various laser powers were successfully fabricated employing the novel manufacturing technology of supersonic laser deposition (SLD). Ti-coated diamond, which was able to enhance the wettability between diamond and copper, was prepared at the optimal parameters via salt bath. Nano-spherical titanium carbides were uniformly distributed on the diamond’s surface to generate a favorable interface bonding with a copper matrix though mechanical interlocking and metallurgical bonding during impact. Furthermore, the results showed that the transition layer acted as a buffer, preventing the breakage of the diamond in the coating. SLD can prevent the graphitization of the diamonds in the coating due to its low processing temperature. The coordination of laser and diamond metallization significantly improved the tribological properties of the diamond/copper composite coatings with the SLD technique. The microhardness of the diamond/copper composite coating at a laser power of 1000 W reached about 172.58 HV0.1, which was clearly harder than that of the cold sprayed copper. The wear test illustrated that the diamond/copper composite coating at a laser power of 1000 W exhibited a low friction coefficient of 0.44 and a minimal wear rate of 11.85 μm3·N−1·mm−1. SLD technology shows great potential in the field of preparing wear-resistant hard reinforced phase composite coatings.
17
Azmat, Ambreen, Shafaq Asrar, Iftikhar Ahmed Channa, Jaweria Ashfaq, Irfan Ali Chandio, Ali Dad Chandio, Muhammad Ali Shar, Mohamad S. AlSalhi i Sandhanasamy Devanesan. "Comparative Study of Biocompatible Titanium Alloys Containing Non-Toxic Elements for Orthopedic Implants". Crystals 13, nr 3 (9.03.2023): 467. http://dx.doi.org/10.3390/cryst13030467.
Pełny tekst źródłaStreszczenie:
Titanium alloys, particularly Ti6Al4V, are commonly used in biomedical applications. However, the inclusion of aluminum (Al) and vanadium (V) in this alloy can cause cytotoxic effects in the human body, resulting in Alzheimer’s disease and cancer. This study compares the performance of biocompatible alloys containing non-toxic elements, such as tin (Sn) and niobium (Nb), which are considered safe for implantation. Two sets of alloys were selected, Ti5Sn and Ti5Sn5Nb, and their properties were compared to Ti6Al4V. First, the alloys were prepared using a power metallurgical technique. Then, their phase analysis, hardness, wear resistance, strength, and corrosion performance in simulated body fluid (SBF) solution were characterized. Optical microscopy was used to study the microstructure, XRD was used to identify phases, and electrochemical testing was conducted to assess the alloys’ anodic and cathodic characteristics. Nanoindentation techniques were used to analyze surface characteristics, such as elastic modulus, nano hardness, and wear resistance. The results showed the alloys containing Nb and Sn had lower corrosion rates in SBF solution compared to Al-containing alloys. Moreover, Nb-containing alloys exhibited the highest hardness, 72% higher than Al-containing alloys. The corrosion-resistant properties of the alloys containing Nb and Sn were higher than those without Nb or Sn, suggesting they may be ideal for orthopedic implants in humans.
18
Reddy, Bijivemula Narayana, Pothur Hema i Chevireddy Eswara Reddy. "Mechanical and Metallurgical Characterisation of CO2 Laser Beam Welding AISI 4130 and AISI 310 Sheets of Steel". Strojnícky časopis - Journal of Mechanical Engineering 71, nr 2 (1.11.2021): 19–30. http://dx.doi.org/10.2478/scjme-2021-0014.
Pełny tekst źródłaStreszczenie:
Abstract Laser Beam Welding (LBW) is the fusion welding technique in which coalescence is produced by heating the work piece by impingement of concentrated beam of laser light. In this paper a full depth butt welding of alloy steel AISI 4130 and stainless steel AISI 310 of 2 mm thickness by using CO2 Laser Beam Welding machine has been performed. Design of experiment is done by using Taguchi method L25 i.e. level 5 by considering process parameters i.e. power, welding speed, beam angle, focal point position and focal length. The experimental output results that are measured for the mechanical properties of welds (Ultimate Tensile Strength and Hardness). The analysis was carried out to explain the influence of the LBW processing parameters values on the mechanical and microstructural aspects. The weld Joint is analysed by Optical Microstructure and Scanning Electron Microscopy (SEM). The Energy Dispersive X-Ray Analysis (EDAX) was carried out to determinate the chemical composition of the weld zone.
19
de Silva, A., i J. A. McGeough. "Surface Effects on Alloys Drilled by Electrochemical are Machining". Proceedings of the Institution of Mechanical Engineers, Part B: Management and engineering manufacture 200, nr 4 (listopad 1986): 237–46. http://dx.doi.org/10.1243/pime_proc_1986_200_078_02.
Pełny tekst źródłaStreszczenie:
Electrochemical arc machining (ECAM) utilizes pulsed power in an electrolyte, in order to remove metal by combined electro-discharge erosion (EDE) and electrochemical dissolution (ECD). In drilling by this technique, EDE occurs at the frontal gap between the cathode-tool and anode-workpiece; in the side gap, ECD is predominant. Machining rates are much greater than those of electrochemical (ECM) and electro-discharge machining (EDM). This paper is concerned with an investigation of the effects of EDE and ECD on the surface integrity of a range of alloys of industrial interest, drilled by ECAM. Chrome, cobalt and low-alloy steels and nickel-based (nimonic) alloys all exhibited a smooth surface finish typical of that found with ECM, for most of the length of the drilled hole, except at the exit. There, metallurgical damage due to EDE was apparent. The surface characteristics with titanium were typical of those found in EDM, with virtually no evidence of ECM action. This effect was attributed to the presence of a tenacious oxide film formed on titanium in water-based electrolytes which effectively blocks ECM.
20
Korzhyk, Volodymyr, Vladyslav Khaskin, Andrii Grynyuk, Oleg Ganushchak, Sviatoslav Peleshenko, Oksana Konoreva, Oleksii Demianov, Volodymyr Shcheretskiy i Nataliia Fialko. "Comparing features in metallurgical interaction when applying different techniques of arc and plasma surfacing of steel wire on titanium". Eastern-European Journal of Enterprise Technologies 4, nr 12(112) (26.08.2021): 6–17. http://dx.doi.org/10.15587/1729-4061.2021.238634.
Pełny tekst źródłaStreszczenie:
This paper reports a study into the regularities of interphase interaction, features in the formation of intermetallic phases (IMPs), and defects when surfacing steel on titanium in four ways: P-MAG, CMT, plasma surfacing by an indirect arc with conductive wire, and PAW. A general tendency has been established in the IMP occurrence when surfacing steel on titanium by all the considered methods. It was determined that the plasma surfacing technique involving an indirect arc with conductive wire is less critical as regards the IMP formation. That makes it possible to obtain an intermetallic layer of the minimum thickness (25...54 μm) in combination with the best quality in the formation of surfaced metal beads. Further minimization of the size of this layer is complicated by a critical decrease in the heat input into the metal, which gives rise to the capability of the surfaced metal to be collected in separate droplets. The formation of TiFe2, TiFe, and the α-Fe phase enriched with titanium in different percentage compositions has been observed in the transition zone of steel surfacing on titanium under different techniques and modes of surfacing. The study has shown the possibility of formation, in addition to the phases of TiFe2 and TiFe, the Ti2Fe phase at low heat input. The technique of plasma surfacing by an indirect arc with conductive wire minimizes the thermal effect on the base metal. When it is used at the border of the transition of the layer of steel surfaced on titanium, the phase composition and structure of the layers in some cases approach the composition and structure of the transition zone of the original bimetallic sheet "titanium-steel" manufactured by rolling. A layer up to 5 μm thick is formed from the β phase with an iron concentration of 44.65 % by weight and an intermetallic layer up to 0.2...0.4 μm thick, close in composition to the TiFe phase. The next step in minimizing the IMP formation might involve the introduction of a barrier layer between titanium and steel.
21
Ali Bash, Maryam A., Ali M. Mustfa, Ali M. Resan, Firas F. Sayyid i Adnan I. Mohammed. "MICROSTRUCTUR AND MICROHARDNESS OF LASER CLADDING Ni BASED ON COLD ROLLED STEEL". IRAQI JOURNAL FOR MECHANICAL AND MATERIALS ENGINEERING 18, nr 2 (4.08.2018): 201–13. http://dx.doi.org/10.32852/iqjfmme.vol18.iss2.85.
Pełny tekst źródłaStreszczenie:
A study is reported of the laser cladding of a nominal composition of Ni 5 wt% Al on coldrolled low carbon steel (0.16 wt% C), using a high power continuous CO2 laser. The severerolled microstructure of steel was changed considerably at the heat affected zones under allspecific energies. The cladded coatings showed the presence of ɣ solid solution and β(NiAlFe) phases. Sound metallurgical bonding with absence of porosity and cracks wasobserved between the substrate and the clad coat at specific energy higher than 80 J/mm2.The ferrite and pearlite microstructure of the substrate was changed to martensite at the regionadjacent to the clad interface. It followed by large grains of austenite/ferrite and pearlite(grain growth zone), fine grains of austenite/ferrite and pearlite (recrystallization zone) andvery small zone of relatively small change of cold structure (recovery zone). The last zonewas confirmed by micro hardness as a recovery zone.This investigation confirms clearly the possibility of formation different structures of graingrowth, recrystallization and recovery at the laser heat affected cold rolled low carbon steel.The observed results suggest the developing of a new technique to obtain tentativefunctionally graded material.
22
Viswanathan, R., S. R. Paterson, H. Grunloh i S. Gehl. "Life Assessment of Superheater/Reheater Tubes in Fossil Boilers". Journal of Pressure Vessel Technology 116, nr 1 (1.02.1994): 1–16. http://dx.doi.org/10.1115/1.2929553.
Pełny tekst źródłaStreszczenie:
Creep rupture failure of superheater (SH)/reheater(RH) tubes is a major cause of forced outages of power boilers. A methodology developed recently by EPRI and its contractors has helped utilities make more informed run/replace decisions for tubes by judiciously combining calculational, nondestructive, and destructive evaluations. In this methodology, the tubes/tube assemblies at risk are identified by ultrasonically measuring the thickest steamside oxide scale and thinnest wall thickness in the tubes. The remaining life of each tube/tube assembly is predicted using a computer code known as TUBELIFE, thus achieving a further level of focus on the tubes/assemblies in the “highest risk” category. Sacrificial tube samples are then removed from the select locations and subjected to laboratory metallurgical evaluation and isostress rupture testing to refine the remaining life estimates. Research has further refined this methodology by validating the ultrasonic technique for scale measurement, identifying the appropriate stress formula and oxide growth laws and evaluating the limitations of creep damage summation rules and isostress rupture test procedures. This paper provides an overview of the research in the field, and establishes a road map for assessing the remaining life of SH/RH tubes.
23
Cote, Danielle L., Bryer C. Sousa, Victor K. Champagne i Richard D. Sisson. "On the Elemental Impact Factor, a Method to Determine an Alloy’s Compositional Influences upon Phase Stability and Metallurgical Material Properties". Materials 13, nr 24 (16.12.2020): 5747. http://dx.doi.org/10.3390/ma13245747.
Pełny tekst źródłaStreszczenie:
Design-driven materials engineering is gaining wider acceptance with the advancement and refinement of commercially available thermodynamic software as well as enhanced computing power. Computationally designed materials are a significant improvement over the more common and resource-intensive experimental approach to materials design by way of trial and error. While not entirely eliminating experimental methods for alloy design, thermodynamic and kinetic models provide accurate predictions of phases within a given alloy, which enables material properties to be calculated. Accordingly, the present paper introduces a new technique that offers a systematic method of material design by way of utilizing commercial computational software, which has been termed the elemental impact factor. In turn, the present manuscript considers Al 6061 as a proof-of-concept metallic alloy system for elemental impact factor substantiation. Effects of chemical composition on resultant equilibrium and metastable material phases as well as properties can be efficiently assessed with the elemental impact factor framework for metallurgical materials design. Desired phases or properties may be produced by adding elements with a positive elemental impact factor, while deleterious phases or undesired properties may be reduced by adding elements with a negative elemental impact factor. Therefore, the elemental impact factor methodology was presented and then demonstrated herein with examples that showcase the technique’s potential applications and utility for integrated structure-processing-property-performance analysis.
24
FAROTADE, G. A., A. P. I. POPOOLA i S. L. PITYANA. "INFLUENCE OF ZrB2 ADDITION ON MICROSTRUCTURAL DEVELOPMENT AND MICROHARDNESS OF Ti-SiC CLAD COATINGS ON Ti6Al4V SUBSTRATE". Surface Review and Letters 25, nr 06 (sierpień 2018): 1950005. http://dx.doi.org/10.1142/s0218625x19500057.
Pełny tekst źródłaStreszczenie:
The microstructural features and microhardness of ZrB2-reinforced Ti-SiC coatings on Ti-6Al-4V substrate were studied. The deposition of these coatings was achieved via laser cladding technique. A 4.0[Formula: see text]kW fiber-delivered Nd: YAG laser was used to deposit the coatings on the titanium substrate at a laser power of 700[Formula: see text]W and a laser scan speed of 0.8[Formula: see text]m/min. An initial Ti-SiC coating was deposited with no ZrB2 addition followed by deposition of two other coatings with the incorporation of ZrB2 powder at 5 and 10[Formula: see text]wt.%. The coatings were examined using scanning electron microscope (SEM) coupled with energy dispersive spectroscopy. SEM images of Ti-SiC-ZrB2 coatings revealed good metallurgical bond between the coatings and the substrate and also a significant increment in dendritic formation and inter-dendritic eutectics during solidification within the [Formula: see text]-Ti matrix, exhibiting the presence of newly formed phases as the weight percentage of ZrB2 increased. Back-scattered electron images also showed the dissolution effect of SiC particles, as the particle–matrix bond strength is influenced by ZrB2 addition. Furthermore, the microhardness of the Ti-SiC coating was enhanced with increasing ZrB2 weight percentage. X-ray diffraction analysis revealed dominant compounds formed during laser material processing. This study deepens the knowledge of possible microstructural features associated with Ti-SiC-ZrB2 cermet coatings.
25
Roberts, D. I., R. H. Ryder i R. Viswanathan. "Performance of Dissimilar Welds in Service". Journal of Pressure Vessel Technology 107, nr 3 (1.08.1985): 247–54. http://dx.doi.org/10.1115/1.3264443.
Pełny tekst źródłaStreszczenie:
Dissimilar metal welds (DMWs) between austenitic and ferritic steel tubing and piping are commonly employed in high-temperature applications in energy conversion systems. Differences in coefficient of thermal expansion between the two types of steel induce thermal stresses at the welds and local metallurgical changes near the low alloy steel/weld metal interface due to prolonged service at an elevated temperature. These phenomena, together with the differences in creep behavior of the materials joined, render the DMWs more prone to failure than welds between similar steels. This has been reflected in relatively high failure rates in DMWs in certain service applications (e.g., in utility power plant boiler tubing). Typically these welds fail by low ductility cracking in the low alloy steel at, or very close to, the fusion line. A project, sponsored by the Electric Power Research Institute (EPRI) and managed by the Metal Properties Council (MPC), has made significant headway over the last three years in understanding the failure modes and causes involved and in developing methods to assess residual life of DMWs. Welds from service in superheaters and reheater tubes and from laboratory simulation tests were examined to establish metallurgical characteristics and failure modes. Three failure modes were identified: (i) Prior austenite grain boundary cracking in the ferritic steel, one or two grains away from the fusion line; this mode was mainly observed in DMWs made with stainless steel filler metal. (ii) Cracking along the weld interface, which occurred in DMWs made with nickel-base filler metal. (iii) Propagation of cracks initiating from oxide notches formed at the weld outside surface; this mode occurred mainly in thin-walled tubes. Creep damage induced by steady and cyclic loading was found to be the predominant mechanism for damage and failure; therefore a dependence of damage on loading levels and service temperature was established. It was also determined that failure susceptibility in DMWs made with nickel-base filler was strongly influenced by the type of microstructure that formed at the low alloy steel/weld metal interface. The technique developed for estimating the condition and remaining life of DMWs in service involves detailed assessment of loading histories to which the welds are subjected, along with the use of empirical quantitative relationships established from both laboratory and service data. The methodology assumes that damage results from the combined effects of self damage (caused by thermal cycling of materials of different expansion coefficients) and service loadings, including both primary loads (e.g., pressure and deadweight) and secondary, or cyclic, loads due to the constrained thermal expansion of the system as a whole. The technique, Prediction Of Damage In Service (designated PODIS), has been found to adequately predict levels of damage in stainless-based DMWs in service. It is currently being developed further to embrace nickel-based DMWs.
26
Ravendra, Jujavarapu Sai, i Palukuri Veerendra. "Studies on Effect of Tool Pin Profiles and Welding Parameters on the Friction Stir Welding of Dissimilar Aluminium Alloys AA5052 & AA6063". International Journal for Research in Applied Science and Engineering Technology 10, nr 4 (30.04.2022): 3077–89. http://dx.doi.org/10.22214/ijraset.2022.41986.
Pełny tekst źródłaStreszczenie:
Abstract: Friction stir welding (FSW) is a solid-state joining process that uses the frictional heat generated by the rotating tool to soften the metals to form the joint. It is an effective technique for joining dissimilar aluminum alloys and finds its application in various fields such as aerospace and automotive industries. FSW process is energy efficient and environment friendly process. This FSW can produce joints with higher mechanical and metallurgical properties. Formerly, FSW was adopted for low melting metals like aluminum alloys. The various FSW parameters play a vital role in determining the quality of the welded joint. The parameters included in the study of different tool pin profiles (circular, pentagon and taper). FEA analysis will be performed for friction stir welding of Aluminum alloy 5052 and AA6063 at different tool pin profiles using ANSYS. This paper mainly focuses on studying the effect of different tool pin profiles on the microstructure and mechanical properties of the dissimilar AA5052 and AA6063 aluminum alloy joints. The weld quality characteristics like microstructure, micro-hardness, and tensile properties of the joints are analyzed and presented for three different tool pin profiles. It is observed from the result that the joint fabricated using three different tool pin profiles exhibits the better mechanical properties when compared to other joints. Index Terms: Friction stir welding, Aluminium alloys, AA5052, AA6063, Dissimilar welding.
27
Ibrayeva, Gulnara, Yuliya Bulatbayeva i Yermek Sarsikeyev. "Building an adaptive hybrid model for short-term prediction of power consumption using a neural network". Eastern-European Journal of Enterprise Technologies 2, nr 8 (116) (30.04.2022): 6–12. http://dx.doi.org/10.15587/1729-4061.2022.254477.
Pełny tekst źródłaStreszczenie:
This paper proposes a step-by-step technique for combining basic models that forecast electricity consumption in an artificial neural network by the method of preliminary selection and further hybridization. The reported experiments were conducted using data on hourly electricity consumption at the metallurgical plant AO ArcelorMittal Temirtau in the period from January 1, 2019, to November 30, 2021. The current research is related to the planned introduction of a balancing electricity market. 96 combinations of basic models were compiled, differing in the type of neural network, the set of initial data, the order of lag, the learning algorithm, and the number of neurons in the hidden layer. It has been determined that the NARX-type network is the most optimal architecture to forecast electricity consumption. Based on experimental studies, the number of hidden neurons needed to form a planned daily profile should equal 3 or 4; it is recommended to use the conjugate gradient method as a learning algorithm. When selecting models from three groups, it was revealed that the conjugate gradient method produces better results compared to the Levenberg-Marquardt algorithm. It is determined that the values of the selected RMSE error indicator take values of 23.17, 22.54, and 22.56, respectively, for the first, second, and third data groups. The adaptive hybridization method has been shown to reduce the RMSE error rate to 21.73. However, the weights of the best models with values of 0.327 for the first group of data, and 0.336 for the second and third ones, show that the individual use of a separate combination of models is also applicable. The devised forecasting electricity consumption model can be integrated into an automated electricity metering system
28
ADESINA, O. S., A. P. I. POPOOLA, S. L. PITYANA i D. T. OLORUNTOBA. "A STUDY ON SCAN SPEED RELATIONSHIP WITH MICROSTRUCTURAL EVOLUTION, PHASE COMPOSITION AND MICROHARDNESS OF Ni-CONTAINING INTERMETALLIC COATINGS ON Ti–6Al–4V USING LASER CLADDING TECHNIQUE". Surface Review and Letters 25, nr 08 (grudzień 2018): 1950035. http://dx.doi.org/10.1142/s0218625x19500355.
Pełny tekst źródłaStreszczenie:
Titanium alloys have been used for variety of engineering applications but their relatively low hardness and low thermal conductivity are shortcomings that have reduced their potential use. In this work, attempts have been made to study the effects of laser scanning speed and admixed fraction of reinforced Ni–Co powders on clad layer formation and its corresponding properties on Ti–6Al–4V. Laser power of 750[Formula: see text]W, beam size of 3[Formula: see text]mm with argon shield gas flow rate of 1.2[Formula: see text]L/min was made constant, while the powders were premixed and deposited on Ti–6Al–4V with varying compositions at different scanning speeds of 0.6 and 1.2[Formula: see text]m/min. The microstructural analysis, phase constituents and hardness properties of Ni–Co intermetallics reinforced clads were also examined. The morphology of the resultant coatings was analyzed using X-ray diffractometry (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS). The research results showed that laser cladding coatings displayed enhanced properties such as fine microstructure and good metallurgical bonding with the substrate containing minimal pores with respect to the substrate. Furthermore, the microstructure revealed the formation of various fractions of interdendritic compounds/intermetallics dispersed within the coating matrix which could be responsible for the increased hardness obtained. The average hardness of the coating was about 856[Formula: see text]HV [Formula: see text], which was about 2.5 times that of the substrate.
29
Graneix, Jeremie, Jean Denis Beguin, Joël Alexis i Talal Masri. "Weldability of Superalloys Hastelloy X by Yb: YAG Laser". Advanced Materials Research 1099 (kwiecień 2015): 61–70. http://dx.doi.org/10.4028/www.scientific.net/amr.1099.61.
Pełny tekst źródłaStreszczenie:
Hastelloy X is a commercially available nickel-chromium-molybdenum superalloy with a good oxidation resistance, a good mechanical properties at high temperature and a significant formability; sine qua criteria for the choice of materials for the production of chambers turbojet combustion which is part of this study [1]. Arc welding technique is commonly used for the manufacturing of parts but the aeronautical requirements becoming increasingly severe especially in terms of reproducibility of geometry and metallurgical grade fillet weld. Laser welding is a viable method of assembly to meet these new demands by its automation to replace longer term the manual TIG welding. The high power CO2laser is extensively used for practical applications such as cutting and welding laser welding. The CO2laser is very used in the industry with regard to Yb:YAG laser which until now was not rather powerful but this changes. The aim of this study was to evaluate the effect of Yb:YAG laser beam parameters on the microstructure and mechanical properties of the laser beam welded superalloys Hastelloy X to define a field of weldability. The implementation of an experimental design approach is required due to the multitude of input parameters and the complexity of the phenomena involved [2-3].
30
Hariyadi, Arif, Helena Carolina Kis Agustin i Ika Dewi Wijayanti. "Metallography Investigation of Dry Corrosion Boiler Tube". Applied Mechanics and Materials 836 (czerwiec 2016): 72–77. http://dx.doi.org/10.4028/www.scientific.net/amm.836.72.
Pełny tekst źródłaStreszczenie:
In-situ (on-site) metallography has been proven as a method to assess metallurgical condition of material without damaging the material (Non Destructive Testing). However in this case, in-situ metallography must be completed together with several analysis to prevent metallography misinterpretation. This paper also provides an overview of inspection technique continuity, together with result from in-situ (on-site) and laboratory analysis.Water wall tube in-situ metallography was conducted during periodic inspection of a 200 MW Steam Power Plant Boiler. It was found another phase beside ferrite and pearlite. The phase is in horizontal direction and suspected as micro crack, delta ferrite or retained austenite.The further investigation was carried out by performing laboratory analysis including: metallography, scanning electron microscopy (SEM) equipped with EDX (Energy-dispersive X-ray spectroscopy) and hardness test.Result of the investigation showed that the phase was oxide as a corrosion product derived from tube surface and hot gas reaction during combustion. The oxide is identical as dry corrosion oxide, without liquid electrolyte. The oxide was only found on fireside tube surface. It also can be described that the fireside tube was over exposed to high temperature as shown the change lamellar pearlite to globular spheroidized pearlite.
31
Radionov, Andrey A., Ivan V. Liubimov, Igor M. Yachikov, Ildar R. Abdulveleev, Ekaterina A. Khramshina i Alexander S. Karandaev. "Method for Forecasting the Remaining Useful Life of a Furnace Transformer Based on Online Monitoring Data". Energies 16, nr 12 (10.06.2023): 4630. http://dx.doi.org/10.3390/en16124630.
Pełny tekst źródłaStreszczenie:
Implementing the concept of a “smart furnace transformer” should stipulate its information support throughout its life cycle. This requires improving techniques for estimating the transformer’s health and forecasting its remaining useful life (RUL). A brief review of the problem being solved has shown that the known RUL estimation techniques include processing the results of measuring the facility state parameters using various mathematical methods. Data processing techniques (deep learning, SOLA, etc.) are used, but there is no information on their application in online monitoring systems. Herewith, fast (shock) changes in the resource caused by the failures and subsequent recoveries of the facility’s health have not been considered. This reduces the RUL forecasting accuracy for the repairable equipment, including transformers. It is especially relevant to consider the impact of sudden state changes when it comes to furnace transformers due to a cumulative wear effect determined by their frequent connections to the grid (up to 100 times a day). The proposed approach is based on calculating the RUL by analytical dependencies, considering the failures and recoveries of the facility state. For the first time, an engineering RUL forecasting technique has been developed, based on the online diagnostic monitoring data results provided in the form of time series. The equipment’s relative failure tolerance index, calculated with analytical dependencies, has first been used in RUL forecasting. As a generalized indicator, a relative failure tolerance index considering the facility’s state change dynamics has been proposed. The application of the RUL forecasting technique based on the results of dissolved gas analysis of a ladle furnace unit’s transformer is demonstrated. The changes in the transformer state during the operation period from 2014 to 2022 have been studied. The RUL was calculated in the intensive aging interval; the winding dismantling results were demonstrated, which confirmed developing destructive processes in the insulation. The key practical result of the study is reducing accidents and increasing the service life of the arc and ladle furnace transformers. The techno-economic effect aims to ensure process continuity and increase the metallurgical enterprise’s output (we cannot quantify this effect since it depends on the performance of a particular enterprise). It is recommended to use the technique to forecast the RUL of repairable facilities equipped with online monitoring systems.
32
Kumar, Anish, Vinod Kumar i Gaurav Sharma. "Experimental Investigation of Multiple Quality Characteristics of Laser Beam Machined Surface using Integrated Taguchi and Fuzzy Logic Method". Journal for Manufacturing Science and Production 16, nr 3 (1.09.2016): 189–99. http://dx.doi.org/10.1515/jmsp-2016-0015.
Pełny tekst źródłaStreszczenie:
AbstractIn laser cutting, the capability of laser cutting mainly depends on optical and thermal properties of work material. The surface quality and metallurgical properties of the product is most important from the point of laser cutting quality. The present research work explores the modeling and optimization of laser beam cutting process parameters by using hybrid approach of Taguchi based fuzzy logic. The multi-response optimization of process parameters has been done to improve geometrical accuracy by minimizing the kerf width and kerf deviation. The four input parameters power, gas pressure, feed rate, pulse frequency and three output parameters kerf width (KW), kerf deviation (KD) and material removal rate (MRR) have been taken for the experimentation work. The S/N ratios taken for the KW and KD is of the smaller-the-better type and MRR is of the higher the better type. The predicting fuzzy logic model is implemented on Fuzzy Logic Toolbox of MATLAB using Mamdani technique. The fuzzy logic theory has been applied to compute the fuzzy multi-response performance index (FMRPI). This performance index is further used for multi-objective optimization. The selected samples were analyzed using scanning electron microscope. The predicted optimum results have been validated by performing the confirmation tests. The confirmation tests showed the considerable reduction in kerf deviation and increase in material removal rate.
33
Akhtar, Shazeen, Naveed Akhtar, Irfan Nadeem i Anjum Tauqir. "Rapid Solidification and Surfaces Alloying Using Continuous CO2 Laser to Generate Ni-Aluminide on Steel". Key Engineering Materials 875 (luty 2021): 329–36. http://dx.doi.org/10.4028/www.scientific.net/kem.875.329.
Pełny tekst źródłaStreszczenie:
Rapidly solidified thin micro-alloyed surface layers are generated by laser melting of plasma thermal sprayed steel surfaces. Samples of carbon steel are plasma sprayed with fine nickel and aluminum powders. Laser surface melting generated a thin localized molten pool of metal with steep horizontal thermal gradient. The latter triggered intense vortex formation in the molten pool which thoroughly mixed the nickel and aluminum powders within the molten pool in a fraction of a second. As the sample is moved away with a predefined velocity, the cold substrate quenched the melt pool, generating rapidly solidified micro-alloyed surfaces. A 2.5 kilowatts continuous carbon dioxide laser was used for surface melting; laser power was maintained at 800 watts while the samples were moved with respect to the laser beam at linear velocities in the range of 100-200 mm/min. The technique generated metallurgical bonded novel surfaces. Depth of the laser modified layer was achieved in the range of 0.2-0.4 mm. Refined microstructures of pre-austenite grain size in the range of 4±2 µm were generated. Micro-hardness measurements of the modified layer indicate an almost three times enhancement in the hardness values; the latter are, in general indicative of mechanical strength of the material. The shape of the solid/liquid interface of the advancing molten pool determines the orientation of the growing dendrites; at higher velocities of sample translation with respect to the laser beam, these are almost parallel to the sample surface. The orientation of the dendrites, the uniformity in surface alloying (within fraction of a second) and the resulting hardness values are explained with the help of the modeled shape of the liquid metal pool. The laser processed material proved to be a flexible technique to synthesize novel surfaces for surface sensitive applications.
34
ADESINA, O. S., G. A. FAROTADE, A. P. I. POPOOLA i D. T. OLORUNTOBA. "INFLUENCE OF CEO2 ADDITION AND SCANNING SPEED ON MICROSTRUCTURE AND TRIBOLOGICAL BEHAVIOR OF LASER-CLAD Ti-Co REINFORCED COATINGS ON Ti-6Al-4V ALLOY". Surface Review and Letters 27, nr 04 (7.08.2019): 1950129. http://dx.doi.org/10.1142/s0218625x19501294.
Pełny tekst źródłaStreszczenie:
Ti-6Al-4V alloy is restricted in industrial application as a result of its relatively low hardness and poor tribological properties. However, the limitations associated with Ti-6Al-4V in severe tribological conditions can be improved via laser cladding technique. In this study, the influence of rare earth oxide (CeO[Formula: see text] addition on microstructure, hardness and tribological behavior of laser-clad titanium–cobalt-based coatings on Ti6Al4V alloy was investigated. The optimized parameters used for laser depositions are laser power 900[Formula: see text]W; beam spot size 3[Formula: see text]mm; powder feed rate 1.0[Formula: see text]g/min; gas flow rate 1.2[Formula: see text]L/min while laser scan speed was varied at 0.6[Formula: see text]m/min and 1.2[Formula: see text]m/min. Thereafter, the coating morphology as well as wear mechanism of the coatings of CeO2 particles (5–10[Formula: see text]wt.%) dispersed in TiCo matrix were investigated via scanning electron microscope (SEM) equipped with energy dispersed spectrometry (EDS), whereas the intermetallic phases present in the coatings were observed using Philips PW1713 X-ray diffractometer (XRD). Furthermore, the micro-hardness values of the coatings were recorded while wear test was carried out using a reciprocating set up (UMT-2 — CETR tribometer). Results revealed that the incorporation of CeO2 particles into the melt pool influenced the morphology of the coatings, thus resulting in finer cellular dendrites, homogenous and strong metallurgical bonding between the laser cladded coating and the substrate. The phases revealed various fractions of interdendritic compounds (CeCo2, Ni3Ti, Co2Ti, CoTi, Al2O3, TiO, AlTi3, and Ce2O[Formula: see text] dispersed within the coating matrix, thus resulting in 2.68 times improvement on the surface hardness and 47.4% reduction in friction coefficient in comparison with Ti-6Al-4V alloy.
35
Gashi, MSc Vlora, Dr Sc Aurel Nuro i MSc Basri Pulaj. "Study of Organochlorinated Pesticide Residues and Polychlorinated Biphenyls in Soil Samples". ILIRIA International Review 3, nr 2 (31.12.2013): 399. http://dx.doi.org/10.21113/iir.v3i2.137.
Pełny tekst źródłaStreszczenie:
This paper presents and discusses the data obtained for organochlorinated pesticides and their residues in the soil samples of agricultural areas. Soil contamination is one of most important factors influencing the quality of agricultural products. Usage of heavy farm equipment, the land drainage, an excessive application of agrochemicals, emissions originating from mining, metallurgical, and chemical and coal power plants and transport, all generate a number of undesired substances (nitric and sulphur oxides, PAHs, heavy metals, pesticides), which after deposition in soil may influence crop quality. Thus, input of these contaminants into the environment should be carefully monitored. Levels of organochlorinated pesticides contamination were evaluated in agriculture areas that are in use. 10 soil samples were taken in agricultural areas Plane of Dugagjini , Kosovo. Representative soil samples were collected from 0-30 cm top layer of the soil.In the analytical method we combined ultrasonic bath extraction and a Florisil column for samples clean-up. The analysis of the organochlorinated pesticides in soil samples was performed by gas chromatography technique using electron capture detector (GC/ECD). Optima-5 (low/mid polarity, 5% phenyl methyl siloxane 60 m x 0.33 mm x 0.25μm film) capillary column was used for isolation and determination of organochlorinated pesticides. Low concentrations of organochlorinated pesticide and their metabolites were found in the studied samples. The presence of organochlorinated pesticides and their residues is probably resulting of their previous uses for agricultural purposes.
36
Safdar, S., L. Li, M. A. Sheikh i M. J. Schmidt. "Thermal history analysis of surface heating of mild steel with different laser beam geometries". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 220, nr 10 (1.10.2006): 1549–57. http://dx.doi.org/10.1243/09544062jmes246.
Pełny tekst źródłaStreszczenie:
Lasers are in use in the material processing industry for well over 30 years now. The way in which the temperature is distributed inside the material is of prime importance in laser material processing, as it directly affects the heating/cooling rates and thermal gradients. Optimization of different laser processes requires control over heating/cooling rate and thermal gradient. Different processes have different requirements of heating/cooling rate and thermal gradient. Knowing these parameters and relevant metallurgical information, one can predict the microstructure and hence control the material properties. To date, majority of laser processing is carried out by using either circular or rectangular beam. At present, the variation in temperature distribution to control the heating/cooling rates and thermal gradients is caused by the variation either in laser power or in scanning speed. Variations in these parameters are often limited by other processing conditions. Although different beam intensity distributions with circular or rectangular laser beams have been studied to improve the process, no other beam geometries have been investigated. The effect of laser beam geometry on laser processing of materials has received very little attention. This article presents an investigation of the effects of different beam geometries including circular, rectangular, and triangular shapes on heating of metallic materials. Finite-element modelling technique has been used to simulate the transient effects of a moving beam for laser surface heating of metals. The temperature distributions, cooling rates, and thermal gradients have been calculated. Some of the results have been compared with the experimental data.
37
Huang, Jinzhan, Zhiqiang Li, Biao Chen, Sen Cui, Zhaolin Lu, Wei Dai, Yuemin Zhao, Chenlong Duan i Liang Dong. "Rapid detection of coal ash based on machine learning and X-ray fluorescence". Записки Горного института 256 (10.11.2022): 663–76. http://dx.doi.org/10.31897/pmi.2022.89.
Pełny tekst źródłaStreszczenie:
Real-time testing of coal ash plays a vital role in the chemical, power generation, metallurgical, and coal separation sectors. The rapid online testing of coal ash using radiation measurement as the mainstream technology has problems such as strict coal sample requirements, poor radiation safety, low accuracy, and complicated equipment replacement. In this study, an intelligent detection technique based on feed-forward neural networks and improved particle swarm optimization (IPSO-FNN) is proposed to predict coal quality ash content in a fast, accurate, safe，and convenient manner. The data set was obtained by testing the elemental content of 198 coal samples with X-ray fluorescence (XRF). The types of input elements for machine learning (Si, Al, Fe, K, Ca, Mg, Ti, Zn, Na, P) were determined by combining the X-ray photoelectron spectroscopy (XPS) data with the change in the physical phase of each element in the coal samples during combustion. The mean squared error and coefficient of determination were chosen as the performance measures for the model. The results show that the IPSO algorithm is useful in adjusting the optimal number of nodes in the hidden layer. The IPSO-FNN model has strong prediction ability and good accuracy in coal ash prediction. The effect of the input element content of the IPSO-FNN model on the ash content was investigated, and it was found that the potassium content was the most significant factor affecting the ash content. This study is essential for real-time online, accurate, and fast prediction of coal ash.
38
Dörfler, S., i Andrea Otto. "Friction Stir Welding of Light Weight Sandwich Materials". Advanced Materials Research 6-8 (maj 2005): 607–14. http://dx.doi.org/10.4028/www.scientific.net/amr.6-8.607.
Pełny tekst źródłaStreszczenie:
Ever since its invention, friction stir welding has been of great interest for the joining of light weight materials. Due to joining in the solid state, friction stir welding inheres characteristic advantages that are unmatched by conventional fusion welding techniques. At the Chair of Manufacturing Technology friction stir welding is employed to develop a process chain for the production of highly load adapted car body components out of aluminum sheet metal and aluminum foam sandwich (AFS) by tailored blanking. In contrast to friction stir welding other materials, special measures have to be taken, since AFS comprises a layered material structure out of two solid aluminum sheet metal cover layers and a powder metallurgically produced core layer. After welding, the tailored blank is subjected to forming, foaming and a final laser cutting process. High temperature capability of the weld seam must be assured, hence foaming of the powder metallurgic core layer requires temperatures of up to 95% of core layer-solidus temperature. Therefore not only mechanical properties are revealed, but also temperature capability is assessed by differential scanning calorimetry (DSC). Additionally the weld seams are tested during foaming by the use of special specimen geometry. Due to the high deformation and temperature while welding and foaming, the metallurgical structure at the weld seam undergoes some modifications, which are subject to metallographic analysis and hardness testing. As an outlook, new material developments towards 6000 aluminum alloys as cover sheet materials will be discussed with regard to the process chain.
39
., Nagaraja, Raviraja Adhikari i T. Yasir. "An investigation into tapping of Al6061/SiC metal matrix composite with straight flute HSS machine tap". Journal of Mechanical Engineering and Sciences 13, nr 1 (29.03.2019): 4575–95. http://dx.doi.org/10.15282/jmes.13.1.2019.16.0386.
Pełny tekst źródłaStreszczenie:
The present study deals with tapping of Al6061/SiC metal matrix composite. Stir casting technique was used for the fabrication of composite. Castings were produced by varying weight percentages of SiC (5%, 7.5% and 10%) of 23μm size in Al6061. The tapping experiments were conducted for the machinability study of Al6061/SiC metal matrix composite using M8 x 1.25 HSS machine taps. The tapping operation was performed under dry condition with different cutting speeds. Torque required for tapping was measured using piezoelectric based 4-component drill tool dynamometer. Surface morphology and profile of thread surfaces were analysed using Scanning Electron Microscope (SEM) and metallurgical microscope. Estimation of progressive flank wear of machine taps was undertaken using profile projector. The performance of HSS machine tap was evaluated in terms of tapping torque, tool flank wear, and surface characteristics of thread surfaces. The flank wear of uncoated HSS machine tap increased with the increase in weight percentage of SiC in Al/SiC composite for a particular cutting speed. Further, when the matrix materials were reinforced by the same kind and the same weight percentage of SiC particles, the flank wear of the tool was found to increase with cutting speed. In addition, the damage caused to thread profiles increased with the increase in cutting speed and weight percentage of SiC.
40
Čapek, Jaroslav, i Dalibor Vojtěch. "Powder Metallurgical Techniques for Fabrication of Biomaterials". Manufacturing Technology 15, nr 6 (1.12.2015): 964–69. http://dx.doi.org/10.21062/ujep/x.2015/a/1213-2489/mt/15/6/964.
Pełny tekst źródła
41
Maklakov, Alexander S., Tao Jing, Alexander A. Nikolaev i Vadim R. Gasiyarov. "Grid Connection Circuits for Powerful Regenerative Electric Drives of Rolling Mills: Review". Energies 15, nr 22 (17.11.2022): 8608. http://dx.doi.org/10.3390/en15228608.
Pełny tekst źródłaStreszczenie:
AC regenerative electric drives (AC REDs) are widely used in metallurgical rolling due to their reliability, efficiency, and power sufficient to maintain the process. This paper reviews the latest achievements in building the grid connection circuits for the main AC REDs of rolling mills. The paper discusses multipulse connection circuits formed by various transformer types and algorithms for preprogrammed pulse-width modulation with selective harmonic elimination technique (PPWM with SHE) of three-level active front ends (AFE), provides the theoretical and practical measurement results, and gives recommendations for improving existing systems. For 6-, 12-, and 18-pulse grid connection circuits, switching patterns of AFE semiconductor modules with a smooth downward trend within the modulation index range from 0.7 to 1.15 are provided. A simulation was performed under comparable conditions on simulation models in the Matlab/Simulink to objectively evaluate the performance and opportunities of 6-, 12-, and 18-pulse grid connection circuits, including the three-level AFE and transformer specifications. The waveforms and spectra of the grid currents and transformer secondary winding phase currents are shown; total harmonic distortion (THD) factors have been calculated up to the 60th harmonic for various PPWM with SHE patterns. The results of simulation and experimental measurement on operating equipment have been compared. The paper is expected to provide a broad overview of multipulse connection circuits of the rolling mill’s main AC REDs, in particular, identify the latest solutions capable of significantly improving their electromagnetic compatibility with the grid. The results obtained are of high genericity and can be used by researchers and engineers to provide the electromagnetic compatibility of non-linear consumers in similar circuits, as well as design them.
42
Prinz, D., V. Arnhold, Hans Peter Buchkremer, A. Kuhstoss, P. Neumann i Detlev Stöver. "Graded High-Porous Microfilters by Powder Metallurgical Coating Techniques". Materials Science Forum 308-311 (maj 1999): 59–64. http://dx.doi.org/10.4028/www.scientific.net/msf.308-311.59.
Pełny tekst źródła
43
Hu, Wangyu, Hengrong Guan, Xiaofeng Sun i Shizhou Li. "Synthesis of Zirconia-Nickel Cermets by a Powder Metallurgical Technique". Materials and Manufacturing Processes 13, nr 2 (marzec 1998): 229–40. http://dx.doi.org/10.1080/10426919808935238.
Pełny tekst źródła
44
Dehghan-Manshadi, Ali, Nicholas Hoye, Bob de Jong i Rian J. Dippenaar. "Resistance Heated Pressing (RHP): A Novel Technique for Fabrication of Titanium Alloys". Key Engineering Materials 520 (sierpień 2012): 341–46. http://dx.doi.org/10.4028/www.scientific.net/kem.520.341.
Pełny tekst źródłaStreszczenie:
A novel powder metallurgical technique for the fabrication of titanium alloys has been developed by utilizing a pressure-assisted, resistance-heating sintering technique. In this technique, the high electrical resistance of oxide layers present on the surface of powder particles has been exploited to ensure effective resistance heating of green compacts. Ti-6Al-4V pre-alloyed powders of 100 µm size were compressed while being heated under a variety of conditions of sintering temperature, pressure and time. The outcomes of our experiments have proven that resistance heating can be a very effective means of heating during powder consolidation. The results have indicated that the required sintering time and temperature in the new resistance-heated sintering technique are much reduced in compared to sinter-press and/or hot isostatic pressing techniques, resulting in a refined microstructure with a concomitant improvement in mechanical properties.
45
Ali, Sajid, i Joonghan Shin. "In-Depth Characterization of Laser-Welded Aluminum-and-Copper Dissimilar Joint for Electric Vehicle Battery Connections". Materials 15, nr 21 (25.10.2022): 7463. http://dx.doi.org/10.3390/ma15217463.
Pełny tekst źródłaStreszczenie:
With advancements in the automotive industry, the demand for electric vehicles (EVs) has remarkably increased in recent years. However, the EV battery, which is a vital part of the EV, poses certain challenges that limit the performance of the EVs. The joining of dissimilar materials for different components affects the electrical and mechanical performances of EV batteries. Laser beam welding is a promising technique for joining Al and Cu for application in secondary battery fabrication because of the precise control over heat input and high process speed. However, the production of Al–Cu joints remains challenging because of the differences between their thermal and metallurgical properties and the resulting formation of brittle and hard intermetallic compounds, which reduce mechanical and electric properties. Thus, it is vital to characterize the weld to improve joint performance and enhance the laser welding process. This study investigates the joining of an Al alloy (AA1050) with Ni-coated Cu using a continuous-wave Yb fiber laser. The evaluation of the weld morphology showed a correlation between the weld characteristics and process parameters (laser power and welding speed). The weld interface width and penetration depth into the lower sheet (Cu) both increased with increasing heat input. Optical microscopy of the weld cross-section revealed many defects, such as voids and cracks. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) was employed to examine the weld microstructure. The composition analysis revealed the presence of mixed morphology of Al–Cu eutectic alloy (α-Al+Θ-Al2Cu) phase in the form of dendrites in the weld fusion zone with traces of the highly brittle Al4Cu9 phase at a high heat input condition. Furthermore, the electrical contact resistance of the weld seam was measured to determine the correlation between heat input and resistance. In addition, Vickers microhardness measurements were performed on the weld cross-section to validate the SEM/EDS results.
46
Timsit, R. S., i D. C. Lauzon. "A novel surface modification technique for aluminum". Journal of Materials Research 9, nr 3 (marzec 1994): 531–34. http://dx.doi.org/10.1557/jmr.1994.0531.
Pełny tekst źródłaStreszczenie:
Surface modification is achieved by coating the aluminum surface with a powder mix of {Si + flux + a metal (Me)} and heating at ∼600 °C for a time interval of the order of 1 min. During heating, the flux melts and dissolves the native surface oxide film on aluminum, thus allowing Si to react with the substrate to form a film of liquid Al-Si alloy of near-eutectic composition. The component Me of the powder coating then reacts with the molten metal layer to modify the metallurgical properties of the surface after solidification.
47
Zhou, Y., i D. C. Jia. "Microstructure of SiCwreinforced Al–12Ti composites prepared by powder metallurgical technique". Materials Science and Technology 15, nr 5 (maj 1999): 569–74. http://dx.doi.org/10.1179/026708399101506111.
Pełny tekst źródła
48
Tsukamoto, Hideaki. "Enhanced Mechanical Properties of Carbon Nanotube/Aluminum Composites Fabricated by Powder Metallurgical and Repeated Hot-Rolling Techniques". Journal of Composites Science 4, nr 4 (20.11.2020): 169. http://dx.doi.org/10.3390/jcs4040169.
Pełny tekst źródłaStreszczenie:
This research aimed to fabricate lightweight and high-strength carbon nanotube (CNT)/aluminum (Al) composites by powder metallurgical and repeated hot-rolling techniques. The fabrication was conducted in three steps: (1) CNT dispersion, (2) preparation of CNT/Al compacts by powder metallurgical slurry methods, and (3) strengthening and refining of CNT/Al composites by repeated hot rolling. The processes of dispersion of CNTs were carried out with dimethylacetamide as a solvent and potassium carbonate as a dispersing agent, which is an inorganic salt, under ultrasonic sonication conditions. Effect of sonication time on dispersion states and mechanical properties was also examined.
49
Goncharov, A. L., M. A. Portnov, A. P. Sliva, I. S. Chulkov i I. E. Zhmurko. "Promising Electron-Beam Techniques for Joining Metal Materials in Power Equipment Designs". Materials Science Forum 906 (wrzesień 2017): 72–79. http://dx.doi.org/10.4028/www.scientific.net/msf.906.72.
Pełny tekst źródłaStreszczenie:
In paper some design elements are considered, manufacturing of welded joints of which being identified with technological and metallurgical difficulties. The possibility of obtaining welded joints of large thickness parts using EBW with the evaluation of mechanical properties is shown, as well as dissimilar compounds of steel and composite on the basis of tungsten and bronze. The optimal modes of electron beam treatment are picked up and the microstructure of the obtained compounds is investigated confirming their quality.
50
Zhang, Dong-Tao, Nai-Xing Cai, Rong-Chun Zhu, Wei-Qiang Liu i Ming Yue. "Low-cost Sm0.7Y0.3Co5 sintered magnet produced by traditional powder metallurgical techniques". Rare Metals 39, nr 4 (27.04.2019): 421–28. http://dx.doi.org/10.1007/s12598-019-01257-8.
Pełny tekst źródła