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1
Rusanescu, Carmen Otilia, Marin Rusanescu, Florina Violeta Anghelina e Ileana Nicoleta Popescu. "Study Deformability Ecological Steel (41Cr4)". Materiale Plastice 55, n. 3 (30 settembre 2018): 357–60. http://dx.doi.org/10.37358/mp.18.3.5029.
Testo completoAbstract (sommario):
In this paper is studied the hot plastic deformability (plasticity and resistance to deformation) for the low-alloyed steel of heat treatment for mechanical engineering in two ways: compression and tension. Groups of low alloy steels is very important in terms of quality and quantity, the products of these steels have developed internal and external market. The plasticity variation were plotted with the temperature and it was established that the plasticity of the steel increases in the range 700-12000C, then decreases as a result of the firing of the grain boundaries, for the bars obtained from ingot and continuous cast blown it was noticed that the plasticity values are very close. Deformation resistance decreases as the temperature increases. The finest granulation was obtained for a final plastic deformation temperature of 8000C and a minimum degree of deformation of 45%.
2
Wang, Yong, Chengyi Zhu, Guangqiang Li, Yulong Liu e Yu Liu. "Influence of Nb Content on Precipitation, Grain Microstructure, Texture and Magnetic Properties of Grain-Oriented Silicon Steel". Materials 13, n. 23 (7 dicembre 2020): 5581. http://dx.doi.org/10.3390/ma13235581.
Testo completoAbstract (sommario):
The effects of Nb content on precipitation, microstructure, texture and magnetic properties of primary recrystallized grain-oriented silicon steel were investigated by various methods. The results show that the precipitates in primary recrystallized sheets are mainly MnS, Nb(C,N), composite precipitates of MnS and AlN, and composite precipitates of Nb(C,N) and AlN. Adding niobium could refine the primary recrystallized microstructure. The steel with 0.009 wt% Nb possesses the finest and the most dispersed precipitates, which contributes to the finest primary recrystallized microstructure due to the strong pinning force. Adding niobium is beneficial to obtain large volume fraction favorable texture for grain-oriented silicon steel, and the effect of Nb addition is not obvious when the content is higher than 0.009 wt%. After final annealing, the steel with 0.009 wt% Nb shows the best magnetic properties, B800 = 1.872 T, P1.7/50 = 1.25 W/kg.
3
Wang, Tie Bao, Chun Xiang Cui, Lin Fang e Shao Jing Bu. "Fracture Behavior and Microstructure of 60Si2MnA Spring Steels Modified by V-Nb Inoculants". Advanced Materials Research 415-417 (dicembre 2011): 1085–89. http://dx.doi.org/10.4028/www.scientific.net/amr.415-417.1085.
Testo completoAbstract (sommario):
The microstructure of V-Nb inoculants after melt spinning was investigated by performing TEM examination and to the sample steels, the prior austenite grain sizes and fracture morphology were investigated by SEM observation. The results show that the V-Nb inoculants obtained is amorphous and the sample steel modified by V-Nb inoculants which make it possible to be a large amount of nucleation centers existing in the form of (V, Nb)C and achieve the effect of grain refinement in the solidification stages of liquid steel has been found to have the finest prior austenite grain sizes and the average prior austenite grain sizes of steel without addition of V and Nb(Steel A), steel microalloyed with V and Nb(Steel B) and steel modified by V-Nb inoculants(Steel C) are respectively 30μm, 20μm and 10μm. Tensile behavior of samples was studied under tempering at 400°C for 30 min after quenching, tensile results show that the fracture of steel modified by V-Nb inoculants appears dimples which represent ductile fracture. However the tensile fracture of V-Nb microalloyed steel is mixture of quasi-cleavages and dimples. Under tempering at 550°C for 30 min, Steel B and Steel C both show a fractograph with cleavage fracture.
4
Rezaei, SRJ, CW Siyayisa, Z. Tang e J. Moema. "The influence of austenitization time and temperature on the austenite grain growth in high Ti-V HSLA steels". Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 40, n. 1 (24 gennaio 2022): 142–49. http://dx.doi.org/10.36303/satnt.2021cosaami.28.
Testo completoAbstract (sommario):
Generally, in high titanium-containing high strength low alloy (HSLA) steels, the challenge is to ensure that an adequate amount of Ti dissolves during soaking for precipitate strengthening during cooling or hot working. Therefore, this work focused on the effect of soaking time and temperature on the austenite grain growth kinetics of HSLA steels, of the three alloys containing 0.1 %Ti, and 0 to 0.12 %V. The samples were austenitized at 1150 and 1280 °C for 1, 2 and 3 hrs and quenched in a 10% NaCl brine. Thereafter, the samples were tempered at 490 °C for 72 hrs in order to reveal the prior austenite grain boundaries. The grain size was analysed by the linear intercept method. The precipitation behaviour was predicted by Thermo-Calc software and confirmed by SEM-EDS. At 1150 °C austenitizing temperature, all three steel grades exhibited the Ti (C, N) (Type 1), (Mn-Ti) (C, S) (Type 2), MnS (Type 3 (Ti4C2S2) (Type 4) and TiC (Type 5) precipitates. After escalating the temperature to 1280 °C, only the TiC dissolved. Type 4 and 5 precipitates were the finest and possibly responsible for the grain size refinement. Consequently, alloy 1 with the highest S content of 140 ppm exhibited the finest grain size at both temperatures.
5
Maubane, Dannis Rorisang Nkarapa, Charles Witness Siyasiya, Kevin Mark Banks e Waldo Edmund Stumpf. "Critical Strain for Complete Austenite Recrystallisation during Rough Rolling of C-Mn Steel and Nb-Ti-V Microalloyed Steel". Materials Science Forum 941 (dicembre 2018): 46–51. http://dx.doi.org/10.4028/www.scientific.net/msf.941.46.
Testo completoAbstract (sommario):
The influence of roughing strain on the extent of austenite recrystallisation in plain carbon steel and Nb-Ti-V microalloyed steel was investigated. Reheating and roughing simulations were conducted on a deformation dilatometer using industrial heating, soaking times, strain and strain rates. The roughing schedules comprised of varying the pass strain magnitude within a typical roughing temperature range. The double stroke method was used to determine the austenite softening fraction. The austenite grain size, prior to and after rolling, was measured on quenched specimens. Grain refinement was achieved in both steels after all rolling schedules. An applied pass strain of 0.15 was sufficient to completely soften the austenite after the first pass and produced the finest recrystallised grain size. This was attributed to sufficient nucleation sites and driving force for recrystallisation compared to lower strains. Partial recrystallisation occurred after the first pass due to the relatively coarse initial grain size. The steel chemistry played an insignificant role in controlling the recrystallisation kinetics at high roughing temperatures. The through-thickness strain distribution calculated from FEM simulations showed that, for a given applied strain, a similar magnitude of deformation is achieved at the centre of a hot-rolled plate.
6
Xu, Jing, e Yi Tao Yang. "Comprehensive Influence of Cr and Si on Hardness and Wear Resistance of Cold Roll Steel". Advanced Materials Research 476-478 (febbraio 2012): 334–39. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.334.
Testo completoAbstract (sommario):
To improve the service performance of Cr-series steel for cold roller, the combined effects of chromium and silicon on hardness and wear resistance of cold roll steel had been studied in this paper on the basis of MC5 cold roll steel. The results showed that, with increasing Si content the hardness tended to decrease when Cr content was about the same. The hardness was the highest and the wear resistance was the best when Cr content was about 6.7% and Si content about 0.6%. The reason for this found by microscopic analysis was that the carbide size was the finest and carbides were the most dispersively distributed. Meanwhile, the amount of carbides was also the largest.
7
Li, An Ming, Xiang Jie Wang e Li Juan Huang. "The Austenite Inverse Phase Transformation Quenching in Zero Time Holding of 20MnV Steel". Materials Science Forum 575-578 (aprile 2008): 1177–83. http://dx.doi.org/10.4028/www.scientific.net/msf.575-578.1177.
Testo completoAbstract (sommario):
The effect of second quenching temperature in zero time holding on 20MnV steel's strength and hardness was studied by the orthogonal regressive principle. The microstructure and property of the steel after austenite inverse phase transformation quenching in zero time holding were analyzed. Experiment results showed that the fine lath martensite of 20MnV steel was obtained through austenite inverse phase transformation quenching in zero time holding at 830°C-930°C. Within the range of Experiment's temperature, the structure of this steel quenched at 830°C is the finest. The microstructure will become coarse and the strength and hardness will become lower if the temperature goes up. The property of this steel can be increased remarkably by austenite inverse phase transformation quenching in zero time holding at lower temperature.
8
Li, Xin Cheng, Yu Ting Luo, Wei Xing Zhu, Xiao Li Wang e Yi Chen. "Effect of Finish Rolling Process on Improvement of Lamellar Tearing Resistance of High-Rise Building Steel". Advanced Materials Research 1049-1050 (ottobre 2014): 460–63. http://dx.doi.org/10.4028/www.scientific.net/amr.1049-1050.460.
Testo completoAbstract (sommario):
A process of finish rolling was researched to enhance lamellar tearing resistant of the high-rise building steel EH36. Experimental results indicate that gain size decreased with the decrease of finish temperature. When the finishing temperature on 840/810/780/750°C respectively, microstructure is finest with the size of 11.4μm. Moreover, the size of TiC precipitation turned ideal as the coiling temperature decreased. When coiling temperature is 550°C, the average size of TiC precipitation is only 0.09μm, refined by 40% relative to the conventional process. The microstructure and precipitation phase size of test steel are both effectively controlled because of the improved process. Therefore, high-rise building steel EH36 is finally prepared, and the lamellar tearing resistance reaches up to 78.2%.
9
Maubane, Rorisang, Kevin Banks, Waldo Stumpf, Charles Siyasiya e Alison Tuling. "The Influence of Initial Grain Size and Strain Sequence of Slab Hot Rolling on the Austenite Evolution of Peritectic Microalloyed Plate Steels". Advanced Materials Research 1019 (ottobre 2014): 339–46. http://dx.doi.org/10.4028/www.scientific.net/amr.1019.339.
Testo completoAbstract (sommario):
The influence of the strain sequence during slab hot rolling (also known as “roughing”) on the evolution of austenite in plain carbon, C-Mn-V and C-Mn-Nb-Ti-V steels was investigated. Reheating and roughing simulations were conducted in a Bähr deformation dilatometer using a constant austenitising temperature, constant soaking time and various heating rates and roughing strain sequences. Stress analysis was used to quantify the austenite softening behaviour and the prior austenite grain size was measured from quenched specimens. The austenite grains of the plain carbon steel were coarser than those of both microalloyed steels, with the C-Mn-Nb-Ti-V grade being the finest due to effective pinning of the grain boundaries. Pass strains greater than 0.2 were sufficient for initiation of dynamic recrystallisation (DRX) for the C-Mn and C-Mn-V steels and led to uniform austenite microstructure with austenite grain sizes less than 40µm after the roughing stage.
10
Mohammadjafar Hadad. "Some Experimental Aspects of Grinding Soft Steel Under Different Machining Conditions". Engineering Science & Technology 1, n. 1 (30 settembre 2019): 8–16. http://dx.doi.org/10.37256/est.11202040.
Testo completoAbstract (sommario):
In this study, the effects of dressing parameters, wheel topography and machining environment on grinding performance of soft steel are investigated. To generate different grinding wheel topographies, dressing speed and depth have been changed during dressing of vitrified Al2O3 wheels using single point diamond dresser. After dressing of grinding wheels, machining tests have been conducted to study the influence of the wheel topography and coolant-lubricant types on the performance of grinding operation. The results suggest that MQL is more suited to grinding of soft material in the finishing step (shallow cut) with the finest dressing than wet and dry grinding.
11
Rodriguez-Ibabe, J. M., e Beatriz López. "Austenite Grain Refinement in Direct Charging Based Thermomechanical Processes". Materials Science Forum 715-716 (aprile 2012): 711–18. http://dx.doi.org/10.4028/www.scientific.net/msf.715-716.711.
Testo completoAbstract (sommario):
Thermomechanical processes based on direct charging routes combined with near net shape technologies have become one of the main industrial production routes. The singularity of the coarse as cast initial austenite grain size, combined with the limited total applied strain during hot working, requires a tailored design of the composition and deformation schedules in order to achieve the required mechanical properties. This becomes more and more complex as higher steel grades combined with thicker sections are incorporated into production. This paper reviews the role played by the interaction of dynamic-metadynamic-static recrystallisation and strain induced precipitation on achieving the finest and most homogeneous austenite microstructures as possible, prior to transformation in the case of Nb, Nb-Mo and Ti microalloyed steels. Special emphasis will be put on the relevance of the kinetics of combined postdynamic softening mechanisms before a complete stop of recrystallisation due to precipitation occurs.
12
Chokkalingam, B., V. Raja, J. Anburaj, R. Immanual e M. Dhineshkumar. "Optimization of Micro-Alloying Elements for Mechanical Properties in Normalized Cast Steel Using Taguchi Technique". Archives of Foundry Engineering 17, n. 2 (27 giugno 2017): 171–77. http://dx.doi.org/10.1515/afe-2017-0070.
Testo completoAbstract (sommario):
Abstract In this study, Taguchi method is used to find out the effect of micro alloying elements like vanadium, niobium and titanium on the hardness and tensile strength of the normalized cast steel. Based on this method, plan of experiments were made by using orthogonal arrays to acquire the data on hardness and tensile strength. The signal to noise ratio and analysis of variance (ANOVA) are used to investigate the effect of these micro alloying elements on these two mechanical properties of the micro alloyed normalized cast steel. The results indicated that in the micro alloyed normalized cast steel both these properties increases when compared to non-micro-alloyed normalized cast steel. The effect of niobium addition was found to be significantly higher to obtain higher hardness and tensile strength when compared to other micro alloying elements. The maximum hardness of 200HV and the maximum tensile strength of 780 N/mm2 were obtained in 0.05%Nb addition micro alloyed normalized cast steel. Micro-alloyed with niobium normalized cast steel have the finest and uniform microstructure and fine pearlite colonies distributed uniformly in the ferrite. The optimum condition to obtain higher hardness and tensile strength were determined. The results were verified with experiments.
13
Xiang, Hong Liang, Dong Liu e Fu Shan He. "Effects of Solution Temperature on Microstructure and Tensile Properties of Casting Duplex Stainless Steel". Advanced Materials Research 146-147 (ottobre 2010): 818–24. http://dx.doi.org/10.4028/www.scientific.net/amr.146-147.818.
Testo completoAbstract (sommario):
In this paper, effects of solid solution treatment temperature on microstructure and tensile properties of casting SAF 2507 super duplex stainless steel were researched by means of optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and tensile test. The results indicate that the amount of γ phase increases according to a linear relationship f(g ) = -0.134T +159.94 during the temperatures from 1100°C to 1250°C. Tensile properties of casting SAF 2507 super duplex stainless steel fluctuate with solution temperature change. Austenitic grain size and morphology are the most important factors on tensile property. The tensile strength is the highest owing to the finest austenitic grain at the solution temperature of 1150°C. The elongation is related to the fracture mode. At 1100 , elongation ration is highest because of the ductile fracture.
14
Yu Pechenkina, M., e O. A. Nasibullina. "Prevention of local corrosion of aluminum alloy pontoons in steel tanks". Journal of Physics: Conference Series 2373, n. 2 (1 dicembre 2022): 022070. http://dx.doi.org/10.1088/1742-6596/2373/2/022070.
Testo completoAbstract (sommario):
Abstract Over the years of existence of the oil and gas industry, increasing the efficiency of equipment at production facilities places increasing demands on operational reliability and durability. The use of aluminum alloys is due to a large range of its features and properties, one of which is the combination of high strength in combination with low density, sufficient corrosion resistance, good moulding ability by casting, pressure and cutting, the possibility of using aluminum parts in all kinds of structures by welding, soldering and other methods. It is important to bear in mind that aluminium alloys do not require regular corrosion coating during operation. It is all about the finest and extremely strong oxide film (0.00001 mm), which forms a reliable adhesion to the metal.
15
Yang, Xiao Ya, Xi Tao Wang e Gen Qi Wang. "Hot Tensile Deformation Behaviors of an AISI 316LN Stainless Steel". Materials Science Forum 817 (aprile 2015): 367–73. http://dx.doi.org/10.4028/www.scientific.net/msf.817.367.
Testo completoAbstract (sommario):
The hot tensile deformation behaviors of 316LN austenitic stainless steel (ASS) were studied on a Gleeble-1500D thermal simulator under the deformation temperature of 1173-1473 K and strain rate of 0.01-1 s-1. The effects of deformation temperature and strain rate on hot deformation behaviors were analyzed. Based on experimental data, the constitutive equation was established, and the predicted peak stresses by the developed model agree well with the experimental data. Microstructure near the fracture and the percentage reduction of area were studied, and the results showed that the microstructural evolution has great influences on the percentage reduction of area. Under the deformation temperature of 1473K with the strain rate of 1s-1, the grain was the finest and most homogenous, and in this deformation condition the percentage reduction of area was the highest of 79.8%.
16
Hara, Yasuhiro, Masahiro Yamada, Chikako Tatsukawa, Tomokazu Takahashi, Masato Suzuki e Seiji Aoyagi. "Fabrication of Stainless Steel Microneedle with Laser-Cut Sharp Tip and its Penetration and Blood Sampling Performance". International Journal of Automation Technology 10, n. 6 (4 novembre 2016): 950–57. http://dx.doi.org/10.20965/ijat.2016.p0950.
Testo completoAbstract (sommario):
The demand for minimally invasive injection needles or needle-shaped tools is growing from those who carry out medical practices such as blood or insulin injections. Applying the mosquito biomimetic, we have used a femtosecond laser to fabricate minimally invasive microneedles out of ultrafine hollow SUS304 pipes, 50μm in outer diameter and 20μm in inner diameter. When such a stainless steel needle tip is angled at 15°, it has the lowest penetration resistance, two and a half times lower than that of the finest hollow needle that is commercially available. A blood suction experiment with a newly developed microneedle has demonstrated that 2.8μellof blood can be drawn out in 20 seconds. Such stainless steel microneedles fabricated by femtosecond lasers have great potential as minimally invasive and mass-producible blood sampling needles to be used for diabetic inspections.
17
Iparraguirre, C., Ana Isabel Fernández-Calvo e Beatriz López. "Effect of Initial Austenite Microstructure on the Softening – Precipitation Interaction in a Low Nb Microalloyed Steel". Materials Science Forum 550 (luglio 2007): 429–34. http://dx.doi.org/10.4028/www.scientific.net/msf.550.429.
Testo completoAbstract (sommario):
The influence of initial grain size on the softening-precipitation interaction in a low niobium microalloyed steel has been investigated. The study has revealed that for the largest initial grain size (1000 μm), the recrystallised fraction remains lower than the softening fraction until relatively long times are reached. In contrast, for the smallest initial grain size (166 μm) both magnitudes are similar. As a result, precipitation interacts with recrystallisation in the case of the finest austenite grain size, whereas for the coarsest one, since recrystallisation is significantly retarded, interaction with recovery process is observed. Apparently, the initial austenite grain size does not affect precipitation kinetics.
18
Liu, Yunqi. "Study on Effect of Tempering Temperature on Microstructure and Properties of Super Martensitic Stainless Steel Welded Joints". Journal of Physics: Conference Series 2499, n. 1 (1 maggio 2023): 012018. http://dx.doi.org/10.1088/1742-6596/2499/1/012018.
Testo completoAbstract (sommario):
Abstract The ultra-martensitic stainless steel ZG06Cr13Ni4Mo, due to its excellent corrosion resistance, good tensile property and excellent weldability, is widely used in many occasions of hydropower, thermal power, and nuclear power, especially as the preferred material for pump impeller. This type of steel has good weldability due to its low carbon content, but the low content of reversed austenite in the weld will lead to poor plastic toughness of the welded joint. The effect of different tempering processes on the microstructure transformation and mechanical properties of welded joints of ultra-martensitic stainless steel was studied. The 20 mm thick test plate was MIG welding and then tempered at 560 °C, 600 °C, and 640 °C for 2 h. The results show that after increasing tempering temperature, the microstructure gradually decreases from the base metal to the weld and gradually transforms from lath martensite to tempered sorbite; When tempering at 600 °C, the microstructure in the weld is the finest, and the size of grain size is 0.274 μm. The highest content of reversed austenite is 9.39%; In the welded joint, compared with the untempered joint, the hardness of the welded joint area decreases after tempering, and the tensile strength first decreases and then increases. The yield strength and elongation gradually increase.
19
Fan, Yun Ying, Ying Jie Zhang e Peng Dong. "Preparation and Property of Electrodeposited Zn-Fe-SiO2 Composite Coating". Key Engineering Materials 373-374 (marzo 2008): 212–15. http://dx.doi.org/10.4028/www.scientific.net/kem.373-374.212.
Testo completoAbstract (sommario):
Electrodeposited Zn and Zn-Fe alloy have been applied widely to protect steel from corrosion, but the property of coating still needs to be improved. In this paper, Zn-Fe-SiO2 composite coatings are electrodeposited from Zn-Fe alloy electrolyte containing SiO2 particles. Zinc based coatings with Fe% >1%(mass) are deposited from sulfate bath, and coatings with Fe% <1%(mass) are deposited from chloride bath. Particle content in the composite coating generally increases with particle concentration under an adequate agitation and then tends to saturation. The optimum particle content in the composite coating is 0.5%(mass). Corrosion resistance, porosity, hydrogen embrittlement and surface morphology of Zn-Fe-SiO2 composite coatings have been tested and compared with electrodeposited Zn and Zn-Fe alloy. The data implies that Zn-Fe-SiO2 composite coating has the best corrosion resistance, lowest porosity, lowest hydrogen content and the finest crystal. All the results show that Zn-Fe-SiO2 composite coating is satisfactory to be used as anti-corrosion material for steel and has a great future in application.
20
Liu, Yajun, Xiaolong Gan, Wen Liang, Guang Xu, Jianghua Qi e Man Liu. "Microstructure Evolution and Mechanical Response of a Direct Quenched and Partitioned Steel at Different Finishing Rolling Temperatures". Materials 16, n. 9 (6 maggio 2023): 3575. http://dx.doi.org/10.3390/ma16093575.
Testo completoAbstract (sommario):
The effects of finishing rolling temperature on the microstructure and mechanical properties of a direct quenched and partitioned (DQ&P) steel were investigated by a thermal simulation machine, a field emission scanning electron microscope (FE-SEM), electron backscattering diffraction (EBSD), and a transmission electron microscope (TEM). The results show that the original austenite grain size was refined by 31% as the finishing rolling temperature decreased from 920 °C to 840 °C, leading to the formation of the finest martensite lath at 840 °C. At the same time, the lower finishing rolling temperature resulted in a higher dislocation density, and consequently improved the stability of the retained austenite. Moreover, compared to the conventional Q&P process, the comprehensive mechanical properties of a steel with similar chemical composition can be enhanced by DQ&P processing. With the decrease of finishing rolling temperature from 920 °C to 840 °C, the strength and total elongation increases. The yield strength, tensile strength, and total elongation reach the maximum values of 1121 MPa, 1134 MPa, and 11.7%, respectively, at 840 °C.
21
Wang, Xuelin, Xiaoya Wang, Wenle Liu e Chengjia Shang. "Effect of Segregation Band on the Microstructure and Properties of a Wind Power Steel before and after Simulated Welding". Metals 14, n. 1 (22 gennaio 2024): 129. http://dx.doi.org/10.3390/met14010129.
Testo completoAbstract (sommario):
This article uses scanning electron microscopy (SEM) and electron back-scattering diffraction (EBSD) to study the effect of C and Mn segregation on the microstructure and mechanical properties of high-strength steel with 20 mm thickness used for wind power before and after simulated welding. A Gleeble-3500 (GTC, Dynamic Systems Inc., Poestenkill, NY, USA) was used to study the microstructure evolution of the simulated coarse-grained heat-affected zone (CGHAZ) of experimental steel under different welding heat inputs (10, 14, 20, 30 and 50 kJ/cm) and its relationship with low-temperature impact toughness (−60 °C). The results indicate that alloy element segregation, especially Mn segregation, significantly affects the impact toughness scatter of the steel matrix, as it induces the formation of low-temperature martensite or hard phase, such as M/A (martensite/austenite) constituent. In addition, segregation also reduces the low-temperature impact toughness of the simulated welding samples and increases the fluctuation range. For high-strength steel with yield strength higher than 460 MPa used for wind power generation, there is an optimal welding heat input (~20 kJ/cm), which enables the simulated coarse-grained heat-affected zone (CGHAZ) to obtain the highest impact toughness due to the formation of lath bainite (LB) and the finest crystallographic block units. Excessive or insufficient heat input can induce the formation of coarse granular bainite (GB) or lath martensite (LM), leading to a larger size of crystallographic block units, reducing the hindering effect of brittle crack propagation and deteriorating low-temperature impact toughness.
22
Shi, Rui Rui, Sui Yuan Chen, Yong Gang Peng e Zhao Zhang. "Effect of Preheating Temperature on Microstructure of Fe Based Alloy Coating by Laser Direct Metal Deposition". Key Engineering Materials 703 (agosto 2016): 94–99. http://dx.doi.org/10.4028/www.scientific.net/kem.703.94.
Testo completoAbstract (sommario):
A Fe60 alloy coating was deposited on the surface of Q235 steel by semiconductor laser under the different preheating temperature at 25°C, 100°C, 150°C, 200°C, 250°C, 300°C respectively. The structure and hardness of the samples were analyzed by the means of OM、SEM、XRD、micro-hardness tester. The results show that: A Fe60 alloy coating with high Cr and C content was prepared on the steel substrate by using optimized process parameters, the interface bonding was formed between the coating and the substrate, the thickness of the coating without cracks and porosities is about 6-10mm. There are equiaxed and dendrite crystals in the coating and the phase of coating is composed of α-Fe, γ-Fe,{Fe,Ni} solid solution, Fe3C, Cr2B, Cr7C3. Preheating treatment has good eliminating coating cracks role in the laser deposited Fe-based coating with high Cr and C content, the sample preheated at 200°C has the finest crystalline structure, and the thickness is 8mm and the hardness is up to 806HV. Preheating treatment is an effective method to eliminate the cracks in the high thickness Fe60 alloy coating by laser direct deposition.
23
Zhu, Zhaoge, Longqing Zou, Huaxing Li e Hongbin Zhang. "Preparation and Characterization of Pulse Electrodeposited Ni/W-SiC Nanocomposite Coating on Mild Steel Substrate". Coatings 13, n. 3 (21 febbraio 2023): 484. http://dx.doi.org/10.3390/coatings13030484.
Testo completoAbstract (sommario):
In order to improve the performances of metal containers, furnace bodies and agricultural tools manufactured by mild steels, Ni/W-SiC nanocomposites are prefabricated on mild steel substrate by the pulse electrodeposition (PED) method. The morphology, texture, microstructure, microhardness, and wear performances of Ni/W-SiC nanocomposites are examined by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), dispersive X-ray spectroscopy (EDX), hardness tester, and friction wear testing. The results indicate that the SiC size in nanocomposites is ~32.4 nm when its concentration in electrolytes is 7 g/L. The S1 and S4 nanocomposites’ microstructures (the S1 composite was prefabricated at 4 g/L, and the S4 composite was deposited at 13 g/L) reveal many large cauliflower-shaped grains. However, the S2 nanocomposite (the S2 composite was obtained at 7 g/L) demonstrates the homogeneous, finest and smoothest surface morphology. The diffraction angles of S1 nanocomposite are 41.2°, 51.7°, and 71.2° depicting the sharpest diffraction peaks, corresponding to the (1 1 1), (2 0 0), and (2 2 0) crystal planes of Ni-W grains, respectively. Moreover, the S2 nanocomposite exhibits the lowest wear depth and width of 34.2 μm and 5.5 mm, respectively. Some shallow and fine scratches on the as-described nanocomposites’ surface indicate its excellent tribological performance. However, the S4 nanocomposite exhibits a wear depth of 86.3 μm and a width of 11.9 mm.
24
Yahy AL-Radi, Helal Hameed, Shen Dejian e Hussein Kareem Sultan. "Performance of Fiber Self Compacting Concrete at High Temperatures". Civil Engineering Journal 7, n. 12 (1 dicembre 2021): 2083–98. http://dx.doi.org/10.28991/cej-2021-03091779.
Testo completoAbstract (sommario):
The goal of this study is to assess the fresh and hardened properties of self-compacting concrete (SCC) prepared using locally available materials. This research includes also the impact of polypropylene (PP), steel and hybrid fibers on the same properties. In addition, the mechanical properties of SCC specimens (with and without fibers) at high temperatures, including as compressive, tensile, and flexural strengths, will be determined. Four different SCC mixtures (with and without fibers) are prepared, tested, and assessed in order to attain these goals. The specimens were heated to various temperatures (200, 400, 600, and 800) at a rate of 5 degrees Celsius per minute for each test. The temperature was remained constant at the target temperature for one hour before cooling to ensure a consistent temperature throughout the specimen. According to the test results, all of the mixes have good consistency and workability in terms of filling and passing ability. In addition, the inclusion of fibers lowered the workability of SCC slightly. Also, the compressive, tensile, and flexural strengths improved with increasing temperature up to 200 °C and dropped at temperatures over 200 °C, according to these findings. Within the SCC, the PP fibers lowered and removed the risk of spalling. Concrete mixtures containing steel fibers and hybrid fibers have the finest mechanical characteristics and spalling resistance as temperature rises. Weight losses were lower in SCC mixtures with PP and steel fibers than in those without PP and steel fibers. As the temperature rose, all SCC mixes lost mass and UPV decreased until the samples spalled (as in plain SCC and SCC with steel fibers) or were questionable (as in SCC with PP and SCC with hybrid fibers). Doi: 10.28991/cej-2021-03091779 Full Text: PDF
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Ryż, Karol, e Łukasz Flaga. "Selected construction and technological problems of middle span length steel bridges based on examples over the Danube and Dnieper river". Budownictwo i Architektura 7, n. 2 (13 dicembre 2010): 005–23. http://dx.doi.org/10.35784/bud-arch.2263.
Testo completoAbstract (sommario):
Every example of bridge both the aesthetic appearance and technological solutions are unique. Differences are a result of a various historical events, neighbour impact and evolving capabilities of bridge building. Based on the unique features of bridge examples taken into consideration one reveals evolution technology of bridge building in time. The aim is to present some examples of steel bridges which have been considered successful. Bridges are still in use. Each of them was created in different period of time. It shows the altered bridge building idea, fluctuation of trend. The successful design was able to have been improved during time when increasing road traffic forced engineers to adapt bridges into new conditions. Bridge builders found a positive solution to every appeared problem. It help to preserve bridges from being rebuild and clearly showed that bridge building is the finest domain of civil engineering.
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Qian, Dongsheng, Bin Chen, Feng Wang e Lingyan Wu. "Rapid Spheroidizing Annealing via Combining Warm Deformation with Divorced Eutectoid Transformation in M50 Steel". Metals 12, n. 2 (20 febbraio 2022): 359. http://dx.doi.org/10.3390/met12020359.
Testo completoAbstract (sommario):
In this work, a novel routine to realize the rapid spheroidizing annealing (SA) process has been proposed in M50 steel via combining warm deformation (WD) and divorced eutectoid transformation (DET). In this process, the sample is first subjected to partial austenitizing to realize the partial dissolution of carbides, then slowly cooled to DET temperature for WD. Finally, the sample is slowly cooled to below the eutectoid transformation temperature to complete the SA. The results show that an excellent spheroidized microstructure can be obtained via the rapid SA process within 2 h. The finest spheroidized carbide (0.295 μm), as well as an appropriate hardness (217 HV), is achieved when the WD and DET processes are conducted at 760 °C. This should be attributed to that the WD not only accelerates the DET but also can break the primary carbides, leading to the uniformly distributed and refined carbides. In addition, the proposed WD that realizes rapid SA shows the excellent roundness of spheroidized carbides compared with the traditional cold/hot deformation which needs a long-term SA process. This work provides a highly efficient routine to simultaneously realize the SA and shape forming, which is of great engineering significance for the manufacturing of bearings.
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Miao, Bin, Jinming Zhang, Jiaxu Guo, Xinxin Ma, Liqin Wang e Xinghong Zhang. "Understanding the Microstructure Evolution of 8Cr4Mo4V Steel under High-Dose-Rate Ion Implantation". Materials 16, n. 17 (28 agosto 2023): 5876. http://dx.doi.org/10.3390/ma16175876.
Testo completoAbstract (sommario):
In this study, the effect of microstructure under various dose rates of plasma immersion ion implantation on 8Cr4Mo4V steel has been investigated for crystallite size, lattice strain and dislocation density. The phase composition and structure parameters including crystallite size, dislocation density and lattice strain have been investigated by X-ray diffraction (XRD) measurements and determined from Scherrer’s equation and three different Williamson–Hall (W-H) methods. The obtained results reveal that a refined crystallite size, enlarged microstrain and increased dislocation density can be obtained for the 8Cr4Mo4V steel treated by different dose rates of ion implantation. Compared to the crystallite size (15.95 nm), microstrain (5.69 × 10−3) and dislocation density (8.48 × 1015) of the dose rate of 2.60 × 1017 ions/cm2·h, the finest grain size, the largest microstrain and the highest dislocation density of implanted samples can be achieved when the dose rate rises to 5.18 × 1017 ions/cm2·h, the effect of refining is 26.13%, and the increment of microstrain and dislocation density are 26.3% and 45.6%, respectively. Moreover, the Williamson–Hall plots are fitted linearly by taking βcosθ along the y-axis and 4sinθ or 4sinθ/Yhkl or 4sinθ(2/Yhkl)1/2 along the x-axis. In all of the W-H graphs, it can be observed that some of the implanted samples present a negative and a positive slope; a negative and a positive slope in the plot indicate the presence of compressive and tensile strain in the material.
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Augspurger, Michael. "Fortune'sBusiness Gentlemen: Culture and Corporate Liberalism in the Early 1930s". Prospects 26 (ottobre 2001): 423–47. http://dx.doi.org/10.1017/s0361233300000995.
Testo completoAbstract (sommario):
Fortuneportentously announced its aim in the first issue in February 1930: “Fortune'spurpose is to reflect Industrial Life in ink and paper and word and picture as the finest skyscraper reflects it in stone and steel and architecture.” The magazine's copious use of painting, literary writing, and artistic photography gave it a luxurious feel that few early reviewers failed to praise. The advertising firm Young and Rubicam, for instance, applauded the magazine's aestheticization of business: “A Toast to YouFortune… You've taken what are sometimes called ‘prosaic business’ and ‘sordid industry’ – you have viewed them with imagination, insight, and beauty … No longer is business a column of figures, or work a daily grind. Here is epic enterprise, a panorama of romance, adventure, conquest – with beauty in factories and derricks.” Upgrading the visual and textual environment of the business magazine,Fortuneprovided business with the elegance of the aristocracy and the allure of a Hollywood star.
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Faisal, Muhammad, Aamer Saeed, Danish Shahzad, Nadir Abbas, Fayaz Ali Larik, Pervaiz Ali Channar, Tanzeela Abdul Fattah, Dost Muhammad Khan e Syeda Aaliya Shehzadi. "General properties and comparison of the corrosion inhibition efficiencies of the triazole derivatives for mild steel". Corrosion Reviews 36, n. 6 (27 novembre 2018): 507–45. http://dx.doi.org/10.1515/corrrev-2018-0006.
Testo completoAbstract (sommario):
AbstractMild steel (MS) corrosion is a worldwide issue that greatly affects the industrial and natural environment. To extend the lifespan of appliances, the control of MS corrosion is necessary. To shield MS from corrosion, specifically from acidic conditions, one of the practical and finest approaches is the application of inhibitors. Triazole derivatives are eco-friendly corrosion inhibitors (CIs) having inconsequential toxicities, excellent inhibition efficiencies (IEs) against corrosion of MS, and extremely high cost-effectiveness. This critical review discusses the general effect of temperature, concentration, time after the application of CI, and type of acid on the IE of triazole derivatives. Further, the review provides an adequate amount of information about the features of excellent CIs; a summary of the reported properties of triazole-based inhibitors, CIs in industries, and current requirements of industries; and recommendations and implications for researchers to improve IE. Additionally, the review also illustrates the mechanisms of action and the IEs, which are evaluated from potentiodynamic polarization parameters, in various acidic media and concentrations of triazole inhibitors. By IE correlation with numerous concentrations and acidic conditions, this review is advantageous and helpful for synthetic chemists to expand the diversity and complexity of a class of triazole derivatives by synthesizing new triazole derivatives.
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Benlamnouar, Mohamed Farid, Nabil Bensaid, Mohammed Oubelkacem Azzoug, Tahar Saadi, Mosbah Zidani e Riad Badji. "Optimization and Evaluation of Mechanical and Electrochemical Properties of Ferritic Stainless Steel Welding Using Taguchi Design". Key Engineering Materials 973 (9 febbraio 2024): 61–72. http://dx.doi.org/10.4028/p-oqmgc5.
Testo completoAbstract (sommario):
The main objective of this work is to optimize welding parameters of AISI 430 FSS welds, focused to minimization of ferrite grains size using Taguchi’s design. Two input parameters of speed and welding current; were chosen to select the minimum grain size and to ascertain their effects on ferrite grain size. ANOVA method was used to evaluate the influence of varying factors on the overall quality of welds. Optimal combination of the parameters were be predicted by S/N analyses, it was accessed on employing an 80 A with 6mm/s. Experimental characterizations of optimum weld joint were performed by using tensile test assisted by image correlations, optical and electronic microscopy. As a result, welding speed had the main influence on grain size by 84.30%. Optimum welding parameter offered finest microstructure with low rate of martensite precipitates in both fusion zone and heat affected zone, and best combination of strength and ductility, it presented a homogeneous distribution of tensile stresses that caused a ductile fracture in base material. ,it is found that that optimized welding parameters permit to give greater resistance to corrosion, which exhibit a lower corrosion current, indicating that coarse ferrite grains are more susceptible to corrosion compared to fine grains.
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Cottreau, Deborah. "Wolfville Doing It Right: Bawtree’s Atlantic Theatre Festival". Canadian Theatre Review 83 (giugno 1995): 72–74. http://dx.doi.org/10.3138/ctr.83.016.
Testo completoAbstract (sommario):
Overlooking the Bay of Fundy, situated in the quaint university town of Wolfville, Nova Scotia, stands a steel-supported wooden ‘O’, a proposed 514-seat skating-rink-turned-theatre, soon-to-be home of the Atlantic Theatre Festival. The brainchild of Artistic Director Michael Bawtree and associates, ATF stands as proof positive that local initiative and grass-roots collaboration are the key to Canada’s cultural future. Other than local residents and area politicians, further contributors include some of Canada’s finest theatrical talent: Christopher Plummer is ATF’s Honourary Fundraising Chairman; Michael Shamata, recently-appointed Artistic Director for London’s Grand Theatre, offers ATF invaluable advice on the daily running of, and casting for, a repertory company; Stratford lighting designer Michael Whitfield provided ATF with their initial requirements for stage lighting. He continues to advise project architect Michael Harvey (Halifax), on the theatre’s structural design. Former Artistic Director of Canada’s Stratford Festival, Michael Langham, is the festival’s Associate Director. On 16 June, 1995, ATF will launch its inaugural season with Langham’s mise en scène of Shakespeare’s The Tempest.
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Buryakovskaya, Olesya A., Musi Zh Suleimanov, Mikhail S. Vlaskin, Vinod Kumar e Grayr N. Ambaryan. "Aluminum Scrap to Hydrogen: Complex Effects of Oxidation Medium, Ball Milling Parameters, and Copper Additive Dispersity". Metals 13, n. 2 (17 gennaio 2023): 185. http://dx.doi.org/10.3390/met13020185.
Testo completoAbstract (sommario):
An effective combination of oxidation medium, ball milling parameters, and copper additive disperstiy ensuring fast aluminum scrap reaction with high hydrogen yield, was suggested. Different milling parameters (5, 10, and 15 mm steel balls; 1 and 2 h; unidirectional and bidirectional rotation modes) were tested for Al-10 wt.% Cu (50–70 μm) composition. The samples milled with 5 (2 h) and 10 mm (1 and 2 h) balls contained undesirable intermetallic phases Al2Cu and Cu9Al4, while those activated with 15 mm balls (1 h) provided the second-finest powder and best preservation of the original Cu and Al phases. Among the tested (at 60 °C) 2 M solutions NaCl, LiCl, KCl, MgCl2, ZnCl2, BaCl2, CaCl2, NiCl2, CoCl2, FeCl2, and AlCl3, the first six appeared to be almost useless (below 4% hydrogen yield), the following four provided better results, and the ultimate 91.5% corresponded to AlCl3. Samples with Cu dispersity of 50–100 nm, 1–19, 50–70, and 150–250 μm, and with no additive, were milled under the optimal parameters and tested in AlCl3. Their total yields were similar (~90–94%), while reaction rates differed. The highest rate was obtained for the sample modified with 50–70 μm powder.
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Feriyanto, Dafit, S. S. Abdulmalik, Hadi Pranoto e Supaat Zakaria. "The Development of Fine Surface Roughness of FeCrAl Substrate by Gamma Alumina Coating Material Through Nickel Oxide Catalyst". International Journal of Advanced Technology in Mechanical, Mechatronics and Materials 2, n. 2 (18 novembre 2021): 70–75. http://dx.doi.org/10.37869/ijatec.v2i2.46.
Testo completoAbstract (sommario):
The most commonly used method for protecting atmospherically exposed steel against corrosion, is the application of protective organic coating systems. It is widely recognized that the stability of the coating-substrate interface is related to the interfacial adhesion forces and electrochemical properties of this region. This study aim to develop fine surface roughness by ultrasonic and electroplating coating methods that applied for FeCrAl catalytic converter. This method consists of thwo methods which are ultrasonic bath that carried out by frequency of 35 kHz and various ultrasonic times of 1, 1.5, 2, 2.5 and 3 hours is imposed and the electroplating was conducted for several variation times of 15, 30, 45, 60 and 75 minutes, current density of 8 A/dm2. The result shows that the surface roughness of UB samples in between 0.11 to 0.21 µm, UBdEL samples of 0.81 to 2.17 µm, UB+EL samples of 0.64 to 1.63 µm and EL samples of 0.69 to 1.11 µm. The finest surface of each techniques are located at UB 1.5 h, UBdEL 45 minutes, UB 1.5 h+EL 30 minutes and UB 30 minutes. That data is supported by coating thickness of coated FeCrAl substrate where UB samples in between 2 -2.8 µm, UBdEL samples of 4.1 to 5 µm, UB+EL samples of 9.1 to 12 µm and EL samples of 6.2 to 11.3 µm.
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Reñones, Anibal, Cristina Vega e Mario de la Rosa. "Vibration-Based Smart Sensor for High-Flow Dust Measurement". Sensors 23, n. 11 (24 maggio 2023): 5019. http://dx.doi.org/10.3390/s23115019.
Testo completoAbstract (sommario):
Asphalt mixes comprise aggregates, additives and bitumen. The aggregates are of varying sizes, and the finest category, referred to as sands, encompasses the so-called filler particles present in the mixture, which are smaller than 0.063 mm. As part of the H2020 CAPRI project, the authors present a prototype for measuring filler flow, through vibration analysis. The vibrations are generated by the filler particles colliding with a robust steel bar capable of withstanding the challenging conditions of temperature and pressure within the aspiration pipe of an industrial baghouse. This paper presents a prototype developed to address the need for quantifying the amount of filler in cold aggregates, considering the unavailability of commercially viable sensors suitable for the conditions encountered during asphalt mix production. In laboratory settings, the prototype simulates the aspiration process of a baghouse in an asphalt plant, accurately reproducing particle concentration and mass flow conditions. The experiments performed demonstrate that an accelerometer positioned outside the pipe can replicate the filler flow within the pipe, even when the filler aspiration conditions differ. The obtained results enable extrapolation from the laboratory model to a real-world baghouse model, making it applicable to various aspiration processes, particularly those involving baghouses. Moreover, this paper provides open access to all the data and results used, as part of our commitment to the CAPRI project, with the principles of open science.
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Kostencki, Piotr, Tomasz Stawicki e Aleksandra Królicka. "The Evaluation of the Effectiveness of Reinforcement by Cemented-Carbide Plates in Two Design Variants of the Chisels Intended for Cultivation–Sowing Aggregates". Materials 14, n. 4 (21 febbraio 2021): 1020. http://dx.doi.org/10.3390/ma14041020.
Testo completoAbstract (sommario):
Field tribological tests of two design variants of chisels used in the teeth of a cultivation-sowing unit were carried out in this research. A characteristic feature of the first variant of chisels was the reinforcement of their contact surface and almost the entire rake surface by plates made of cemented carbides. On the other hand, the second variant of chisels was reinforced only in the area of the blade by two plates made of cemented carbides, soldered on the rake face of the elements. The use of the first variant of chisels contributed to a significant reduction in the wear rate of elements, especially in terms of thickness and width loss. Effective reinforcement of the rake face, with relatively lower resistance to length reduction in the elements, raises doubts as to the validity of the use of cemented-carbide plates on almost the entire length of their rake face, because the applied variant of chisels contributed to a significantly higher price. However, the second variant of chisels effectively limited the intensity of the loss of the length of the elements, and the cause of the loss of their usefulness as part of the base material wear. It was found that the main wear mechanism of the cemented-carbide plates consisted of matrix removal under the influence of the finest fraction of the soil, which weakened the embedding of carbides, and then crushing or chipping of carbide grains from the matrix, whereas the dominant wear mechanisms of martensitic steel were grooving and micro-cutting.
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Anggraini, Lydia, e Kalimi. "Welding Shape Control of Cross Member Backbone Assembly by Automatic Gas Metal Arc Yaskawa-MA1440 Type". Key Engineering Materials 877 (febbraio 2021): 90–95. http://dx.doi.org/10.4028/www.scientific.net/kem.877.90.
Testo completoAbstract (sommario):
In order to prevent distortion caused by heat which affects the material deformation, the properties controlled are required. The properties changes and the placement of the mounting position will effect the weld strength that causes cracks and broken joints, therefore it affects the safety of machine construction. Thus, the objective of this paper is to control the shape of cross member backbone assembly by gas metal arc welding (GMAW). The welding is produced by an automatic robot Yaskawa-MA1440 type. In order to obtain the good quality of the result, the welding shape is controlled by a parameters combination of voltage, current, and speed. Yaskawa-MA1440 type is used as the automatic welding machine. The main material used is cold rolled steel coil sheet MJSC270D-OD with a thickness of 1.2 mm. In addition, to control the welding shape, the specified shape design standard is followed include travel speed, gas flow, welding direction, torch tip distance to the workpiece, torch angle and welding angle. The results of visual and dimensional were also examined in this research. Furthermore, the macrostructure i.e. leg length, fusion penetration, throat thickness have been analyzed and confirmed based on the standards used in the auto body vehicle part company. The appropriate parameters for the finest welding shape are defined at the horizontal position using an electric current of 120 A and the welding voltage of 18 V (± 1 V). Thus, the measurement control of macrostructure is defined as reference parameters for mass production of cross member backbone assembly.
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Bartkowiak, Tomasz, Karol Grochalski, Bartosz Gapiński e Michał Wieczorowski. "Discrimination of Surface Topographies Created by Two-Stage Process by Means of Multiscale Analysis". Materials 14, n. 22 (20 novembre 2021): 7044. http://dx.doi.org/10.3390/ma14227044.
Testo completoAbstract (sommario):
The fundamental issue in surface metrology is to provide methods that can allow the establishment of correlations between measured topographies and performance or processes, or that can discriminate confidently topographies that are processed or performed differently. This article presents a set of topographies from two-staged processed steel rings, measured with a 3D contact profilometer. Data were captured individually from four different regions, namely the top, bottom, inner, and outer surfaces. The rings were manufactured by drop forging and hot rolling. Final surface texture was achieved by mass finishing with spherical ceramic media or cut wire. In this study, we compared four different multiscale methods: sliding bandpass filtering, three geometric length- and area-scale analyses, and the multiscale curvature tensor approach. In the first method, ISO standard parameters were evaluated as a function of the central wavelength and bandwidth for measured textures. In the second and third method, complexity and relative length and area were utilized. In the last, multiscale curvature tensor statistics were calculated for a range of scales from the original sampling interval to its forty-five times multiplication. These characterization parameters were then utilized to determine how confident we can discriminate (through F-test) topographies between regions of the same specimen and between topographies resulting from processing with various technological parameters. Characterization methods that focus on the geometrical properties of topographic features allowed for discrimination at the finest scales only. Bandpass filtration and basic height parameters Sa and Sq proved to confidently discriminate against all factors at all three considered bandwidths.
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Kunschert, Georg, Hans Peter Martinz e Michael Schütze. "Investigation of Oxide-Nucleation on Ferritic FeCr Interconnect Alloys for Solid Oxide Fuel Cells Exposed to Anode and Cathode Gases at 850°C". Materials Science Forum 595-598 (settembre 2008): 779–87. http://dx.doi.org/10.4028/www.scientific.net/msf.595-598.779.
Testo completoAbstract (sommario):
In recent years solid-oxide fuel cell (SOFC) interconnect components have proven to be a key-component accountable for the functionality of high temperature fuel cells. Amongst adequate thermal expansion and high temperature strength, highest oxidation resistance in anode and cathode gases under thermal cycling conditions is required in order to reach long term durability, particularly when using thin film light-weight components with particular focus on automotive applications. In order to match the challenging parameter profile Plansee developed the mechanically alloyed ITM, a ferritic P/M Fe26Cr alloy strengthened with additions of Y2O3 dispersoids, since it has been observed that apart from their HT strengthening effect, which is of specific interest for thin sheets components, finest ODS particles reduce the growth and enhance the adhesion of the forming oxide layers. The latter effect is of particular interest in applications where alloys are exposed to HT cyclic conditions. In this work the nucleation phase of the oxide scale formation on P/M ODS Fe26Cr ITM is compared to that on a reference ingot steel Fe22Cr in typical anode gases containing significant amounts of H2, CO and approximately 3% H2O as well as in laboratory air at 850°C. Thermal cycling oxidation tests following the COTEST standard up to 168h are carried out in both environments. Moreover cyclic oxidation tests are performed in dry anode gas. Detailed studies of oxide scale formation and evolution by means of electron microscopy of cross sections as well as oxide surfaces are undertaken.
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Zhu, Zhengyu, Maoyang Ran, Xuyang Li, Pichang Ma, Shubin Liu e Jiayou Wang. "Microstructure and Hardness Characteristics of Swing-Arc SAW Hardfacing Layers". Materials 17, n. 10 (13 maggio 2024): 2310. http://dx.doi.org/10.3390/ma17102310.
Testo completoAbstract (sommario):
Hot-rolled backup rolls are widely used in steel rolling and usually need to be repaired by arc hardfacing after becoming worn. However, a corrugated-groove defect commonly occurs on the roll surface due to the uneven hardness distribution in the hardfacing layers, affecting the proper usage of the roll. Accordingly, a new swing-arc submerged arc welding (SA-SAW) process is proposed to attempt to solve this drawback. The microstructure and hardness are then investigated experimentally for both SAW and SA-SAW hardfacing layers. It is revealed that a self-tempering effect occurs in the welding pass bottom and the welding pass side neighboring the former pass for both processes, refining the grain in the two areas. In all the zones, including the self-tempering zone (STZ), heat-affected zone (HAZ), and not-heat-affected zone in the welding pass, both SAW and SA-SAW passes crystallize in a type of columnar grain, where the grains are the finest in STZ and the coarsest in HAZ. In addition, the arc swing improves the microstructure homogeneity of the hardfacing layers by obviously lowering the tempering degree in HAZ while promoting the even distribution of the arc heat. Accordingly, the hardness of the SA-SAW bead overall increases and distributes more uniformly with a maximum difference of < 80 HV0.5 along the horizontal direction of the bead. This hardness difference in SA-SAW is accordingly decreased by ~38.5% compared to that of the SAW bead, further indicating the practicability of the new process.
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Henke, Thomas, Markus Bambach e Gerhard Hirt. "Die and Process Design for Hot Forging of a Gear Wheel – A Case Study". Key Engineering Materials 554-557 (giugno 2013): 307–16. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.307.
Testo completoAbstract (sommario):
Gearing components are an example for widely used machining parts in engines. Nowadays the development and optimization of materials and process chains are driven towards a concurrent improvement of final product properties and production efficiency. Excellent mechanical properties needed for gearing components e.g. high load capacity and high fatigue resistance depend on a fine homogeneous microstructure in the final product. Efficiency in gear manufacturing can be optimized by increasing the temperature during processing, which allows for lower forging loads and lower die stresses, thus improving die life in terms of mechanical fatigue. Additionally, increasing the temperature during case hardening reduces the process duration significantly. Hence process efficiency also increases. To meet the need of a fine homogenous microstructure, dynamic recrystallization has to be initiated during hot forging and grain growth has to be avoided during dwell times and case hardening. This grain size control can be achieved by applying micro-alloying concepts. Recently, an Nb-Ti-based alloying concept for case hardening steels was introduced, which increases fine grain stability and therefore potentially allows for higher forging and case hardening temperatures, leading to improved process efficiency [1]. In this paper a 25MoCr4-Nb-Ti steel grade is characterized in terms of flow resistance and microstructure evolution by hot compression tests and annealing experiments. The processing limits of this material in terms of abnormal grain growth are determined and a JMAK-based microstructure model considering these limits is presented and implemented in the FE-Software DEFORM 3dTM. The model is used in a case study to design a laboratory scale forging process for lowest possible die stresses and finest possible grain sizes. Experimentally measured grain sizes and forging loads from forgings at the laboratory scale are used to evaluate the process design. It is shown that considering microstructure evolution in process design is absolutely necessary to jointly optimize for process efficiency and final properties. The application of the Nb-Ti-based micro-alloying concepts allows for lower die stresses and thus seems to reduce mechanical fatigue of the dies compared to conventional case-hardening steels. [1] S. Konovalov et. al.: Testcase gearing component. In: G. J. Schmitz, U. Prahl (Ed.): Integrative Computational Materials Engineering, Wiley-VCH Verlag GmbH & Co. KGaA, 2012, ISBN 978-3-527-33081-2
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Snyder, Robert E. "Margaret Bourke-White and the Communist Witch Hunt". Journal of American Studies 19, n. 1 (aprile 1985): 5–25. http://dx.doi.org/10.1017/s0021875800020028.
Testo completoAbstract (sommario):
Margaret Bourke-White (1904–1971) has been called “the most famous woman photographer” and “the finest woman photographer of our times.” Indeed, in a photographic career that spanned nearly five decades, Bourke-White demonstrated great professional versatility, registered many photographic firsts, and in a male-dominated field set standards by which others were measured. During the 1920s, Bourke-White carved out her first reputation in architectural and industrial photography. Her pictures of steel mills, shipyards, packing houses, logging camps, quarries, auto plants, skyscrapers, banks, and terminals captured the atmosphere of the industry and the dynamics of the capitalist system. Her industrial photography was of such outstanding quality that, as one critic observed, it “transformed the American factory into a Gothic cathedral.”Henry Luce was so impressed by her early work that he hired her as the first photographer for his business magazine Fortune. Under a unique arrangement she was allowed six months out of the year to pursue her own private studio practice for advertising agencies and corporations. When Henry Luce added the pictorial magazine Life to his growing publishing empire in the 1930s, he selected Margaret Bourke-White to become one of the four original staff photographers. At Life she established the tradition of negatives printed full frame and proved by black borders, and pioneered the synchronized multiple flash picture. Bourke-White revealed the range of her photographic talents in photo essays, murals, and documentary travelogues. “As a result of her twelve- and fourteen-page essays,” Carl Mydans noted, “her monumental work became known throughout the world — beyond that of any other photographer.”
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Goswami, Vinod Kumar. "RENOWNED EXPERIMENTAL ARTIST SURENDRA PAL JOSHI". ShodhKosh: Journal of Visual and Performing Arts 4, n. 2 (24 agosto 2023): 118–22. http://dx.doi.org/10.29121/shodhkosh.v4.i2.2023.98.
Testo completoAbstract (sommario):
Surender Pal Joshi one of the finest artist of India. Who was very much established in his field. He had his own style for his art works and that is why he was also known as an experimentalist, as he was always ready to come up with new experiments. His art works hold a very wonderful charm that everyone who sees them, tends to get mesmerized. He was born in the year 1958 in a village close to Dehradun. He did his primary and secondary education from Dehradun itself. After that he shifted to Rishikesh for his BA (Bachelor’s In arts) and then did his B.F.A (Bachelor’s in fine arts) from Lucknow University. He completed his BFA in 1985 as the top performer in the entire college. After that he went to Jaipur for further studies and from there itself his actual journey of becoming one of the finest artist of India started. He came up with new Creativity, New experiments, and a whole new series of his art works. Many of them were exhibited at Lalit Kala academy Jaipur in 1988 and it received a lot of appreciation. His paintings also used to depict an essence of Sufi assembly. He was also quite influenced by the great poet "Kabir" and did made many art works that used to portray Kabir's sayings. And that's how he got to know about the power of experimantalism. His art works also used to depict an essence of mother nature. And gradually he understood his areas of strength. With the power of his imagination and experiments he started his own journey of failures and success.With time he started making his art works in different mediums like Metal, Board ceramic, Tera Cota, Wood steel, Glass, brass and what not. He tried everything that was possible whatever seemed not. made it possible too. Not only in India but his art works started receiving appreciation from other countries too. Became an international name. He was also bestowed with National awards. Now he started with a different form that was modern art works but with a traditional touch. His series were also named as " Taana-Baana". With years of hard work, risk taking abilities, with power of his imagination and experiments he became a sensation. And was always appreciated for his great ideas and designs. He was also called to visit various countries. He was also a professor in School of Art and served their from 1988 till 2004. He tool VRS and then decided to be a free artist. His years of hard work got him many awards, scholarships, and Fellowships. In 2013, impressed with his hard work and dedication, The Uttarakhand government proposed an idea to make a museum for him with all his art works installed. It was inaugurated in 2016. And in 2018 this great man departed from this world, leaving behind a whole big Era. He'll always be alive in our hearts, and I'll always be grateful for his teachings and guidance
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Ciampa, Donato, Raffaele Cioffi, Francesco Colangelo, Maurizio Diomedi, Ilenia Farina e Saverio Olita. "Use of Unbound Materials for Sustainable Road Infrastructures". Applied Sciences 10, n. 10 (17 maggio 2020): 3465. http://dx.doi.org/10.3390/app10103465.
Testo completoAbstract (sommario):
The growing environmental sensitivity and the reduction of natural resources create, in Italy and other developed countries, an increasing interest in the search for alternative materials to be used in road construction works. In recent years, the problems related to environmental sustainability have made it increasingly difficult to remove natural aggregates from quarries and, at the same time, the regulations for the management of waste dumps are more and more restrictive. For this reason, the use of recycled aggregates is experiencing a continuous increase in the civil construction sector. This paper deals with the study of construction and demolition waste (CDW) in the field of road construction, in particular for the construction of embankment, road subgrades, foundation layers and unbound bases for flexible superstructures. Three different particle size fractions were used to prepare the mixtures: the first having a coarse size and designation 0–63 mm, the second intermediate size with aggregates of 0–31.5 mm grain size and the third with the finest aggregates having a grain size of 0–4 mm. The study was carried out by analyzing three granulometric fractions, verifying the best application for each of them. Subsequently, the mix-design was investigated, operating in compliance with the requirements imposed by UNI 11531-1, EN ISO 14688, EN 13242 and EN 13285. For the unbound layers of subgrade, foundation and base, which require greater resistance to fragmentation, the use of CDW alone has shown some limitations. Therefore, in the experimentation, it was decided to mix the CDW with a granulated slag coming from the steel production in the electric arc furnaces (EAF) and with an additional CDW (0–31.5 mm) coming from the recovery of concrete with slag. EAF granulated slag was used in small quantities, due to its relatively high cost. Four eco-friendly and recycled mixtures were studied, with low economic impact and high environmental sustainability, suitable for the construction of unbound layers of road superstructures.
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Tong, Jiaqi, Caibin Wu, Yihan Wang, Jingkun Tian, Zheyang Li, Feng Xie, Xin Yao e Guisheng Zeng. "Effect on Fine Particles Output Characteristics of Ceramic Ball Grinding". Minerals 13, n. 11 (7 novembre 2023): 1416. http://dx.doi.org/10.3390/min13111416.
Testo completoAbstract (sommario):
Steel balls as traditional grinding media are prone to excessive fines generation and high energy consumption. Therefore, in light of this problem, the authors investigated another media—ceramic balls based on the output characteristics of fine particles. This study discusses the effect of ceramic balls on the change of the particle size distribution, zero-order output characteristics, micro-strain, and collision energy in ground products. The results showed that for −10 μm particle size, ceramic balls have a smaller production rate than steel balls. In addition, when the filling rate of ceramic balls is 40%, the yield of −10 μm is reduced compared to steel balls. Therefore, ceramic balls greatly reduced the overgeneration of fines. Additionally, the micro-strain rate of ceramic ball grinding with time is 67% lower than that of steel ball grinding. Furthermore, ceramic balls cannot only mitigate excessive fines generation but also effectively reduce energy consumption.
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Khan, Rehan, Hamdan H. Ya, William Pao, Mohd Amin Abd Majid, Tauseef Ahmed, Amir Ahmad, Mohammad Azad Alam, M. Azeem e Hassan Iftikhar. "Effect of Sand Fines Concentration on the Erosion-Corrosion Mechanism of Carbon Steel 90° Elbow Pipe in Slug Flow". Materials 13, n. 20 (16 ottobre 2020): 4601. http://dx.doi.org/10.3390/ma13204601.
Testo completoAbstract (sommario):
Erosion-corrosion of elbow configurations has recently been a momentous concern in hydrocarbon processing and transportation industries. The carbon steel 90° elbows are susceptible to the erosion-corrosion during the multiphase flow, peculiarly for erosive slug flows. This paper studies the erosion-corrosion performance of 90° elbows at slug flow conditions for impact with 2, 5, and 10 wt.% sand fines concentrations on AISI 1018 carbon steel exploiting quantitative and qualitative analyses. The worn surface analyses were effectuated by using laser confocal and scanning electron microscopy. The experiment was conducted under air and water slug flow containing sand fines of 50 µm average size circulated in the closed flow loop. The results manifest that with the increase of concentration level, the erosion-corrosion magnitude increases remarkably. Sand fines instigate the development of perforation sites in the form of circular, elongated, and coalescence pits at the elbow downstream and the corrosion attack is much more obvious with the increase of sand fines concentration. Another congruent finding is that cutting and pitting corrosion as the primitive causes of material degradation, the 10 wt.% sand fines concentration in carrier phase increases the erosion-corrosion rate of carbon steel up to 93% relative to the 2 wt.% sand fines concentration in slug flow.
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Bolobov, Victor I., Stanislav A. Chupin, Vladimir S. Bochkov, Erik V. Akhmerov e Vyacheslav A. Plaschinskiy. "The Effect of Finely Divided Martensite of Austenitic High Manganese Steel on the Wear Resistance of the Excavator Buckets Teeth". Key Engineering Materials 854 (luglio 2020): 3–9. http://dx.doi.org/10.4028/www.scientific.net/kem.854.3.
Testo completoAbstract (sommario):
An analytical review of the effect of high-temperature thermomechanical treatment on the structure and properties of steels as a possible effective method of strengthening the teeth of excavator buckets. It is shown that the application of this method can have a positive effect not only on the hardness, but also on the entire complex of their mechanical characteristics, such as plasticity, impact toughness and fatigue resistance. In relation to Hadfield steel as the most frequently used material of the bucket teeth, it is noted that with increasing deformation grade of billets from 1 to 5, tensile strength of steel increases from 570 to 1030 MPa, yield strength – from 480 to 790 MPa, relative elongation – from 14.3 to 17.9 %, relative contraction – from 17.2 to 20.1 %, impact strength KCU – from 1.51 to 2.14 MJ/m2. This article presents the results of metallographic analysis and comparative tests for abrasive wear of Hadfield steel samples after typical heat treatment practiced at bucket teeth manufacturers and thermomechanical treatment. It is established that high-temperature plastic deformation of steel samples before quenching increases their wear resistance by 1.7 times. The authors attribute the detected increase in wear resistance to the formation of fine martensite in the surface layers of steel with a needle size of 3-10 nm, which increases its hardness by 47%. It is concluded that the presence of fine martensite in the structure of Hadfield steel can increase the service life of excavator bucket teeth made of this material. The results of this study are planned to be used in the development of an improved technological process for manufacturing bucket teeth of excavators.
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Poh, H. Y., Gurmel S. Ghataora e Nizar Ghazireh. "Soil Stabilization Using Basic Oxygen Steel Slag Fines". Journal of Materials in Civil Engineering 18, n. 2 (aprile 2006): 229–40. http://dx.doi.org/10.1061/(asce)0899-1561(2006)18:2(229).
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Ashrit, Shrenivas, Ravikrishna V. Chatti, Udayabhanu G. Nair e Venugopal Rayasam. "Study of thermogravimetric curves of LD Slag size fractions in oxygen and nitrogen atmosphere and effect of FeO and free lime on weight loss at different temperatures". Metallurgical Research & Technology 115, n. 4 (2018): 417. http://dx.doi.org/10.1051/metal/2018017.
Testo completoAbstract (sommario):
The thermogravimetric (TG) method offers a new approach to the study of the thermal degradation of LD Slag fines, which is a by-product produced in the Tata Steel plant, Jamshedpur during the steel making process. TG curves for LD Slag fines of different particle sizes in oxygen and nitrogen atmosphere from 100 to 900 °C were compared to each other to find the variation in the weight loss. Effect of FeO and free lime on weight loss of LD Slag fines was also discussed. Weight loss in the temperature range of 450–550 °C and then up to 700 °C confirmed the presence of calcium hydroxide, magnesium hydroxide, calcium silicate hydrate and calcite in LD Slag fines. Except −6.0 + 2.0 mm LD Slag fines, the weight loss in oxygen atmosphere is more than nitrogen atmosphere for other size fractions. The higher weight loss in nitrogen atmosphere than the oxygen atmosphere was attributed to the decomposition of calcium silicate hydrate and hydrated aluminate phases. Higher free lime values in finer LD Slag fractions than the coarser LD Slag fractions confirmed more volumetric stability of coarser LD Slag size fractions than the finer fractions due to powdering in the cooling process.
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BIRKS, N., e A. G. F. ALABI. "Mechanisms of Autoignition of Finely Divided Steel". Mineral Processing and Extractive Metallurgy Review 10, n. 1 (marzo 1992): 155–64. http://dx.doi.org/10.1080/08827509208914082.
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Okamura, Sigeru, Eizo Miyauchi e Tokushige Hisatsugu. "Outgassing measurement of finely polished stainless steel". Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 9, n. 4 (luglio 1991): 2405–7. http://dx.doi.org/10.1116/1.577287.
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