Articoli di riviste: "Tensile zone"

1

Zhou, Yi, Meng Cui, Dequan Zhou, Xiaojia Wang e Xiao Fu. "Meso-Experimental Study on Tensile Characteristics of Clay". Advances in Civil Engineering 2021 (29 marzo 2021): 1–16. http://dx.doi.org/10.1155/2021/8875903.

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This paper presents an experimental study on the meso-structure change of clay using an innovative testing system. It aims to evaluate the tensile characteristics of clay. The testing system designed in this paper includes a tensile loading device, an image acquisition device, and an image processing program, which can collect and process the meso-structural images of the soil sample and predict the location of tensile fracture zone with a small preloading. The tests were conducted with three different observation zones, including the tensile fracture zone (Zone 1), the adjacent area of tensile fracture zone (Zone 2), and the areas away from the tensile fracture zone (Zone 3). The results show that the development of cracks is continuous but not linear until tensile failure in Zone 1, and the cracks emerge but stop developing in Zone 2 with the penetration of the cracks in Zone 1, while there is only an overall deviation without any cracks in Zone 3. The variety of mesostructural quantitative parameters in Zone 1 can be divided into three stages: stable stage, rapid change stage, and failure stage. The changes of parameters in Zone 2 show a similar law with those in Zone 1, but the variation is smaller due to the cessation of cracks. The parameters in Zone 3 essentially remain unchanged throughout the whole procedure. According to the test results, the whole stretching process of clay can be divided into the sprouting, the development, and the penetration of cracks.

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Zheng, Yi, Yao Hui Liu, Yu Lai Song, Jia’an Liu, Ling Nan Kong e Yan Liang. "Effect of Welding Heat Input on Microstructure and Softening Behavior of 5CrMoV Steel". Key Engineering Materials 735 (maggio 2017): 42–48. http://dx.doi.org/10.4028/www.scientific.net/kem.735.42.

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Three different heat input combinations for the medium carbon alloy steels 5CrMoV are compared in terms of the heat affected zone of microstructures, hardness, and tensile properties. The microstructures in the heat affected zone are predominately ferrite and bainite, with grain size variation in different sub-zones and different heat input. Analyses of the micro-hardness profiles indicated that softening phenomenon occurs in the entire heat affected zone, and high heat input resulted in the greatest decrease in hardness. The results of the tensile tests reveal tensile properties of the heat affected zone deteriorate with the increase of heat input, and the region at temperatures near Ac1 is the weakest part of heat affected zone.

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Darwis, Mardis, Rudy Djamaluddin, Rita Irmawaty e Astiah Amir. "Analisis Pola Kegagalan Balok Sistem Rangka dengan Perkuatan di Daerah Tumpuan". Jurnal Penelitian Enjiniring 24, n. 1 (26 ottobre 2020): 17–23. http://dx.doi.org/10.25042/jpe.052020.03.

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The previous research of using truss system reinforcement in the beam without concrete (BTR) in the tension zone causes a decrease in flexural capacity due to the failure in the area near the support. Therefore, it is necessary to add tensile reinforcement in the support zone. This study aims to analyze the ultimate capacity of the truss system concrete beam strengthened with tensile reinforcement and to analyze the effect of tensile reinforcement in support zone due to crack pattern. This study was conducted experimentally in the laboratory. The dimension of truss reinforced concrete specimens are 15 cm x 20 cm x 330 cm that added tensile reinforcement with three types of length, they are BTRP 40D, BTRP 50D, and BTRP 60D, where D (13 mm) is diameter of tensile reinforcement. The flexural test is carried out by monotonic static loading. The results showed that tensile reinforcement in BTRP 40D was not able to carry the ultimate capacity due to premature failure in the support zone. while BTRP 50D and BTRP 60D specimens can enhance the ultimate capacity without facing premature failure in the support zone. The tensile reinforcement of 60D has the highest ultimate capacity because it can carry the biggest loads and minimum crack pattern.

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EL-NEMER, SAMIR. "INHOMOGENEOUS DEFORMATION ZONE IN TENSILE SPECIMEN". International Conference on Applied Mechanics and Mechanical Engineering 1, n. 1 (1 maggio 1986): 35–42. http://dx.doi.org/10.21608/amme.1986.51834.

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Baskutis, Saulius, Jolanta Baskutiene e Edvinas Bernotaitis. "Experimental Study of Welded Joints of Aluminium Alloy AW6082". Solid State Phenomena 260 (luglio 2017): 212–18. http://dx.doi.org/10.4028/www.scientific.net/ssp.260.212.

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This paper considers mechanical properties of the welded joints of aluminium alloy AW6082 under varying metal inert gas welding conditions, determined by tensile and microhardness tests. The test joints were produced at different welding current and welding speed. Cross sections of the welding zones have been analysed. The influence of heat input on the tensile strength properties and hardness of the base metal, heat affected and fusion zones were studied. The behaviour of double-V butt weld joints was investigated by tensile tests. Static tensile test and metallographic examination results showed minimum strength in the heat affected zone (HAZ). It was found that the lowest hardness values were obtained in the fusion zone and near the fusion line where rupture occurred.

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Chen, Qing Feng, Zhong Hui Chen, Ning Ma, Wei Zhang e Hui Li. "The Zonal Disintegration Law within Coal in Front of Working Face in Deep Coal Mine". Applied Mechanics and Materials 353-356 (agosto 2013): 1082–89. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.1082.

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The mining coal in the front of long wall face consists of elastic zone, plastic zone and fracture zone. Based on the research of zonaldisintegration of surrounding rock mass in deep tunnel, the zonal disintegration phenomenon of deep coal mine was analyzed by using the theoretical analysis method. On the basis of the Griffith theory, the internal and external boundary formulas of fracture zone and the mechanical criteria of zonal disintegration were obtained. The research shows that the essence of zonal disintegration is the tensile failure and brittle tension crack failure under the abutment pressure, the main influence factors of the width variation of fracture zone are original rock stress and un-axial tensile strength of coal.

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Snider, G. R., J. Lomakin, M. Singh, S. H. Gehrke e M. S. Detamore. "Regional Dynamic Tensile Properties of the TMJ Disc". Journal of Dental Research 87, n. 11 (novembre 2008): 1053–57. http://dx.doi.org/10.1177/154405910808701112.

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Although the TMJ disc has been well-characterized under tension and compression, dynamic viscoelastic regional and directional variations have heretofore not been investigated. We hypothesized that the intermediate zone under mediolateral tension would exhibit lower dynamic moduli compared with the other regions of the disc under either mediolateral or anteroposterior tension. Specimens were prepared from porcine discs (3 regions/direction), and dynamic tensile sweeps were performed at 1% strain over a frequency range of 0.1 to 100 rad/sec. Generally, the intermediate zone possessed the lowest storage and loss moduli, and the highest loss tangent. This study further accentuates the known distinct character of the intermediate zone by showing for the first time that these differences also extend to dynamic behavior, perhaps implicating the TMJ disc as a structure primarily exposed to predominantly anteroposterior tension via anterior and posterior attachments, with a need for great distension mediolaterally across the intermediate zone.

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NESSLER, J. P., P. C. AMADIO, L. J. BERGLUND e K. N. AN. "Healing of Canine Tendon in Zones Subjected to Different Mechanical Forces". Journal of Hand Surgery 17, n. 5 (ottobre 1992): 561–68. http://dx.doi.org/10.1016/s0266-7681(05)80242-6.

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The effect of external force environment on the healing of a partial thickness injury to canine flexor tendon was studied. A 50% laceration was made in either the fibrocartilaginous (compressive) zone or in the tendinous (tensile) zone of canine flexor digitorum profundus tendons. After three or six weeks, the tendons were harvested. An optical method for determining zone-specific material properties showed that, in response to injury, the structural stiffness decreased in the tensile zone of the tendon but increased in the compressive zone. The mechanical properties and failure mechanism of canine tendon and their changes in response to injury vary according to tendon zone, and differences in the healing process in mechanically specialised zones of the flexor tendon are discussed.

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9

Parasuraman, Prabhuraj, Tushar Sonar e Selvaraj Rajakumar. "Microstructure, tensile properties and fracture toughness of friction stir welded AA7075-T651 aluminium alloy joints". Materials Testing 64, n. 12 (29 novembre 2022): 1843–50. http://dx.doi.org/10.1515/mt-2022-0212.

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Abstract The main objective of this investigation is to study the microstructure, tensile properties and fracture toughness of friction stir welded (FSW) butt joints of 10 mm thick AA7075-T651 plates. The microstructural features of stir zone (SZ), thermos-mechanically affected zone (TMAZ), heat affected zone (HAZ) were analyzed using optical microscopy technique. The tensile properties were evaluated using smooth and notch tensile specimens and compared to base metal properties. The microhardness survey was done across the weld cross section and correlated to the failure of tensile specimens. Compact tension (CT) specimens were used to evaluate the fracture toughness of welded joints. The fractured tensile and CT specimens were analyzed using scanning electron microscopy (SEM). Results showed that the FSW AA7075-T651 specimens welded using axial load of 12 kN, tool rotation speed of 750 rpm and welding speed of 30 mm/min exhibited 412 MPa tensile strength and 9% elongation. It showed 88 and 89% of base metal strength elongation. The joints showed fracture toughness of 23 MPa m1/2 which is 80% of base metal fracture toughness. The superior tensile and fracture toughness properties of joints are mainly attributed to the evolution of finer grains in SZ due to the stirring action of FSW tool.

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Li, Juan, Honglong Zhao, Nian Zhou, Yingzhe Zhang, Qingdong Qin, Daoyi Wang, Jianguo Jiao, Guoli Tang e Yonghua Li. "Study on Microstructure of Fiber Laser Welding of CoCrCuFeNi High Entropy Alloy". Materials 15, n. 24 (8 dicembre 2022): 8777. http://dx.doi.org/10.3390/ma15248777.

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A CoCrCuFeNi high-entropy alloy was successfully welded in this study using fiber laser welding. The effects of the welding parameters on the microstructure and mechanical properties were studied. Three zones were formed: the fusion zone, partial melting zone, and base metal. The base metal exhibited a typical dendrite structure, and the Cu element segregated in the interdendrite. The fusion zone consisted of fine equiaxed crystals and columnar crystals with the same crystalline structure as the base metal. The fusion zone exhibited minimal compositional microsegregation after laser welding. Electron backscatter diffraction results showed that the low-angle grain boundary fraction in the fusion zone increased. Furthermore, some dislocations and dislocation pile-ups were present in the fusion zone, and the densities of the dislocations and dislocation pile-ups were higher than those of the base metal. The hardness of the fusion zone was considerably higher than that of the base metal, while the ultimate tensile strength and elongation values were lower than those of the base metal for all conditions. The ultimate tensile strength and the elongation increased gradually and then decreased with increasing laser power. The maximum ultimate tensile strength exceeded that of the base metal by 90%.

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Abolusoro, Olatunji P., e Esther T. Akinlabi. "Effects of processing parameters on mechanical, material flow and wear behaviour of friction stir welded 6101-T6 and 7075-T651 aluminium alloys". Manufacturing Review 7 (2020): 1. http://dx.doi.org/10.1051/mfreview/2019026.

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Dissimilar friction stir welding (FSW) between 6101-T6 and 7075-T651 aluminium alloys was conducted. Three different parameters each were investigated for rotational speed and travel speed, and the effects of these parameters on the tensile behaviour, hardness and wear were evaluated. The results indicate that the ultimate tensile strength increases with an increase in the feed rate. However, the increase in rotational speed decreases the ultimate tensile values. The fractured analysis of the tensile samples shows similarities in the fractured pattern as all the samples failed at heat affected zone close to the 6101-T6 alloy. The hardness varies across the heat affected zones and nugget zone both at constant rotational speed and welding speeds. The highest resistance to wear occurred at 65 mm min−1 and 1850 rpm welding speed and rotational speed respectively while better material mixing was achieved at the nugget zone of the welds at 1250 rpm and 110 mm/min.

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Chen, Yu, Xing Hua Chen e Shuang Wang. "Mechanism of Welding Test Pieces in Tensile Property Anomaly". Advanced Materials Research 472-475 (febbraio 2012): 1147–50. http://dx.doi.org/10.4028/www.scientific.net/amr.472-475.1147.

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Aiming at the mechanical property abnormality of a certain cylinder test piece for aerospace application, scanning electron microscope and metallographic microscope were used to observe and analyze the fracture and weld structure of test pieces under tensile test, and the reason of property abnormality was determined. On the fracture of welding test pieces under tensile test formed two evident characteristic zones, one of which was the initial zone looking like arc ribbons alternating with each other. More obvious texture structure formed in the welding heat affected zone, with the direction consistent with that of the fracture in the up arc zonal fracture region. The reason of the abnormality was that relatively significant texture structure formed in the welding heat affected zone, while its formation was related to the temperature field and stress during the process of welding.

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Ran, X. Z., H. Cheng, D. Liu, S. Q. Zhang, H. B. Tang e H. M. Wang. "Microstructure and Mechanical Properties of Plasma Arc Welding Joint for Laser Melting-Deposited AerMet100 Ultrahigh-Strength Steel". Materials Science Forum 789 (aprile 2014): 424–30. http://dx.doi.org/10.4028/www.scientific.net/msf.789.424.

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The repair of laser melting-deposited AerMet100 ultrahigh strength steel (UHSS) heat-treated samples with groove machined was conducted by low-cost plasma arc welding (PAW). And the microstructure and mechanical properties of welding joint were examined by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-hardness test and the tensile mechanical test. The experimental results indicated that the welding zone with low hardness values mainly consisted of columnar grains with about 200μm width which epitaxial growth from substrate grains, and in which the cellular morphology character appearing at the bottom in comparison with dendrite with lateral branching appearing at the top. Three zones, i.e., sufficient quenched zone, insufficient quenched zone and high-temperature tempered zone, were divided by heating affected temperature and microstructure characteristic in heat affected zone (HAZ), and there was a lowest hardness value region distributed in high-temperature tempered zone. Compared to that of undamaged heat treated forged one, the tensile mechanical property of the repaired laser melting deposited sample got a few decrease but was still well, in which the tensile strength σb, yield strength σs, elongation δ5 and reduction of area Ψ was 1627Mpa, 1285Mpa, 10.5% and 45% respectively. In addition, the isothermal thermal simulation test surveyed that the tensile fracture position locating in high-temperature tempered zone with the lowest hardness value could ascribe to the growth of alloy carbide and increase of reverted austenite in over-aged temperature.

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Peng, Ru Lin, Jin Ming Zhou, Sten Johansson, Annethe Bellinius, Volodymr Bushlya e Jan Eric Ståhl. "Influence of Dry Cut and Tool Wear on Residual Stresses in High Speed Machining of Nickel-Based Superalloy". Materials Science Forum 768-769 (settembre 2013): 470–77. http://dx.doi.org/10.4028/www.scientific.net/msf.768-769.470.

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Machining induced residual stresses were investigated in Inconel 718 prepared by high speed turning under dry cut condition. The influence of cutting tool wear and the use of cutting fluid were studied. By x-ray diffraction measurements, characteristic residual stress distributions with tensile stresses in the top layer and compressive stresses in the layer below were found in all the investigated samples. The magnitude of surface tensile stresses and size of the tension as well as compression zones varied depending on the cutting condition. The application of cutting fluid for turning using new tool has a minor effect, giving a somewhat larger subsurface compressive zone but reducing the surface tensile stresses. Tool flank wear has shown a much stronger effect. While a flank wear of VBmax=0.15 mm enhanced mostly the surface tensile residual stresses, a severer wear of VBmax=0.3 mm greatly increased the thickness of the subsurface compression zone and at the same time resulted in strong stress anisotropy. Microstructural study by electron channelling contrast imaging shows that the observed influence of tool flank wear or cutting fluid on residual stresses are related to different contributions from increased plastic deformation and cutting heat, which changed with the cutting conditions.

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Zhou, Guang, Xin Qi Yang e Xiao Dong Xu. "Study on Mechanical Behaviors in Friction Stir Welding of 6061-T4 T-Joints". Advanced Materials Research 418-420 (dicembre 2011): 1092–96. http://dx.doi.org/10.4028/www.scientific.net/amr.418-420.1092.

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Friction stir welding (FSW) of T-joints composed by 3mm thick 6061-T4 alloy was presented and the influences of process parameters on hardness profiles and tensile strength were discussed specifically. Two low hardness zones on the skin and one low hardness zone on the stringer were found. Tensile behaviors of T-joints were examined in two directions—in skin direction and in stringer direction. It was found that the tensile strength ranged from 170~180MPa for all specimens in the skin direction. And the specimens failed in heat affected zone (HAZ) corresponding to the lowest hardness. In the stringer direction, most fractures occurred in the stringer. In all the cases, the specimens welded exhibited the best tensile strength with ω/v=1541/218 in the stringer direction. The ultimate tensile strength was equal to 83% compared to base material.

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Mahdi, Elsadig, E. Eltai, Fatima Ghassan Alabtah e Faysal Fayez Eliyan. "Mechanical Characterization of AA 6061-T6 MIG Welded Aluminum Alloys Using a Robotic Arm". Key Engineering Materials 913 (18 marzo 2022): 271–78. http://dx.doi.org/10.4028/p-rhrr3n.

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Aluminum alloys are of particular interest in the design of lightweight structures in different applications. Accordingly, welding aluminum alloys (AA) is a critical issue; for example, welding defects could arise during the traditional welding of aluminum alloys. This paper investigates the effects of welding using a robotic arm on the mechanical properties of 6061-T6 Aluminum alloy, as plates joined by Metal Inert Gas (MIG) welding. The tensile behavior and mechanical properties were investigated using tensile testing, hardness testing, and impact testing. The tensile behavior of AA-6061-T6 un-welded and welded specimens showed a decrease in the tensile strength of the welded specimens due to the fusion of the welded zone and the partially melted zone (PMZ). The hardness test showed an increase in the hardness values away from the welded zone, attributed to voids and defects in the welded and HAZ zones. In addition, the impact behavior showed that the maximum impact is in the base metal zone, and the minimum is in the HAZ. Scanning electron microscopy was used to investigate the welded and un-welded Aluminum microstructures. The mechanical properties of AA 6061-T6 Aluminum alloy were sensitive to the novel welding process.

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Mani, Cherish, Sozharajan Balasubramani, Ramanujam Karthikeyan e Sathish Kannan. "Digital Image Correlation of Tensile Properties for Monel 400/SS 316L Dissimilar Metal Welding Joints". Materials 14, n. 6 (22 marzo 2021): 1560. http://dx.doi.org/10.3390/ma14061560.

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Dissimilar metal weld joints of Monel 400 and Stainless Steel 316L stainless steel were carried out using Gas Tungsten Arc Welding (GTAW). Conventional annealing and cryogenic treatment were performed on the welded joints. Weld joints of this combination of materials have enormous potential applications in power industry and the available related literature is limited. In the present study, the tensile properties of heat treated (HT), cryotreated (CT), and untreated (UT) specimens were studied. The engineering stress and strain were determined experimentally as per Standard Test Methods for Tension Testing of Metallic Materials (ASTM E8). The strain distribution was evaluated at different zones of weld joint was evaluated using Digital Image Correlation (DIC). Significant difference was noticed between the zones. Weld zone of all samples had less local stress and strain and SS 316L heat affected zone (HAZ) zone had more local stress and strain when compared to other zones. The local strain distribution along distance from weld center line and local stress-strain curves of different zones are also predicted. Scanning Electron Microscopy was used to analyze the fracture behavior of welded samples for HT, CT, and UT specimens.

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Xu, Tian Han, Yao Rong Feng, Sheng Yin Song, Zhi Hao Jin e Dang Hui Wang. "Investigation of Fracture Mechanism of Casing-Drilling Steels". Advanced Materials Research 197-198 (febbraio 2011): 1647–50. http://dx.doi.org/10.4028/www.scientific.net/amr.197-198.1647.

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The paper reports on an investigation of the fracture mechanism of both tensile and impact fracture in three types of casing-drilling steels. The results show that the tensile fracture surface of N80 steel includes fibrous zone, radiation area and shear lip zone, and those of both K55 and P110 steels include two zones; all the tensile fracture surfaces of three types of casing drilling steels show the ductile fracture mode, the ductile fracture mode indicated with dimples is observed on all zones; the impact fracture surface of the N80 steel possesses a combined quasi-cleavage and ductile fracture modes, a single fracture mode is observed on the fracture surface of both K55 and P110 steels, the K55 steel impact sample is fractured in a cleavage brittle manner, whereas the P110 steel impact sample is fractured in a dimpled ductile manner.

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Gu, Sen Dong, Ji Peng Zhao, Rui Jie Ouyang e Yong Hong Zhang. "Microstructural Characterization and Tensile Behavior of TA1 Titanium Alloy Sheet Welded by Electron Beam Welding". Materials Science Forum 1027 (aprile 2021): 149–54. http://dx.doi.org/10.4028/www.scientific.net/msf.1027.149.

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In the present study, TA1 titanium alloy sheets with a thickness of 0.8mm were welded by electron beam welding. Microstructure of the welded region was investigated using optical microscope and electron backscattered diffraction. Then, the tensile test was conducted to analyse the tensile behavior of the welded sheets as well as the fractography of the fracture surfaces. It is shown that the mean grain size in the heat-affected zone is smaller than that in the fusion zone and base material. The strength of the base metal is lower than that of the fusion zone and heat-affected zone. The average values of the yield strength, tensile strength and elongation of the tensile specimens are 224MPa, 335MPa and 35%, respectively. In addition, the tensile specimens of the welded sheets suffer both ductile and brittle deformation during the tensile tests.

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D., Antony Prabu, e Subbaiah K. "Microstructure and Mechanical Behavior of Sc Doped Filler Rod in TIG Welding Dissimilar Al Mg Alloys". Journal of New Materials for Electrochemical Systems 24, n. 3 (30 settembre 2021): 143–50. http://dx.doi.org/10.14447/jnmes.v24i3.a01.

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The present work reports about the effect of cast scandium doped ER5356 filler rod in Tungsten Inert Gas welding of dissimilar Aluminium Magnesium alloys. The grain refinement effect on weld microstructure by transition metal scandium was investigated with optical and scanning electron microscope. Additionally, XRD analysis, tensile strength (global and component joint) and microhardness were tested on weld samples. The microstructural examination in weld fusion zone observed fine grain size and suppressed dendrite arm spacing. The formation of Al3Sc precipitate in weld fusion zone due to scandium inclusion in filler was identified and resulted in improving the weld strength significantly. The higher joint efficiency of 92.5% was achieved in the global joint of weld samples. The failure location of global joint tensile samples identified the weld fusion zone is stronger than AA5052 base material. Further weld strength was evaluated with component joint by micro tensile test, which results in 70MPa enhancement in UTS values and validating the accurate weld strength. However, the elongation of the tensile test sample reduced marginally for the weld. The fracture mechanism of the weld joint observes decrease in ductility. The significant increase in hardness of the weld fusion zone was evident due to doping of scandium compared to the other zones of the weld.

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Lin, Sen, Jianguo Tang, Shengdan Liu, Yunlai Deng, Huaqiang Lin, Hua Ji, Lingying Ye e Xinming Zhang. "Effect of Travel Speed on Microstructure and Mechanical Properties of FSW Joints for Al–Zn–Mg Alloy". Materials 12, n. 24 (12 dicembre 2019): 4178. http://dx.doi.org/10.3390/ma12244178.

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The microstructures and mechanical properties of friction stir welded (FSW) Al–Zn–Mg alloy plate under different travel speeds were investigated. Both the average grain sizes (AGSs) of the shoulder affected zone (SAZ), nugget zone (NZ), and the widths of thermo-mechanically affected zone (TMAZ) decreased with the increase of travel speed. Moreover, the AGSs of NZ are always about 60% of that of SAZ at different travel speeds. The fractions of high-angle grain boundaries (HAGBs) in the FSW joints reduce with the distance away from the stir zone (SZ). Furthermore, the initial η’ strengthening precipitates in NZ and TMAZ dissolve and GP zones form during subsequent natural aging, so that the hardness is similar in the two zones. The precipitate evolution in the heat-affected zone (HAZ) at hardness minima are affected by travel speeds, which induce the hardness minima and ultimate tensile strength (UTS) of FSW joints and increase with the increase of travel speed, and a fracture tends to occur at hardness minima location of HAZ during tensile testing.

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Li, Jian Wei, Zhong Su, Gui Ping Lv, Li Jun Pang e Wei Jia. "Peak-To-Peak Change in Magnetization Caused by Fracture". Advanced Materials Research 787 (settembre 2013): 755–58. http://dx.doi.org/10.4028/www.scientific.net/amr.787.755.

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To simulated the magnetization change at the instant of fracture, assume that the distribution of dislocation-magnetic dipole is consistent, the models of dislocation-magnetic dipole for tensile fracture and tensile-tensile fatigue fracture are established, respectively: The distribution of magnetic dipole for tensile fracture is linear increase from distant to the fracture zone, while the distribution of magnetic dipole for tensile-tensile fatigue fracture is converging only at the fracture zone. It is found that the established model can present the change of peak-to-peak in magnetization for tensile fracture and tensile-tensile fatigue fracture.

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Yu, Yang, Yi Hua Dou, Fu Xiang Zhang e Xiang Tong Yang. "Analysis of Premium Connection of Connecting and Sealing Ability Loaded by Axial Tensile Loads". Applied Mechanics and Materials 268-270 (dicembre 2012): 737–40. http://dx.doi.org/10.4028/www.scientific.net/amm.268-270.737.

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It is necessary to know the connecting and sealing ability of premium connection for appropriate choices of different working conditions. By finite element method, the finite element model of premium connection is established and the stresses of seal section, shoulder zone and thread surface of tubing by axial tensile loads are analyzed. The results show that shoulder zone is subject to most axial stresses at made-up state, which will make distribution of stresses on thread reasonable. With the increase of axial tensile loads, stresses of thread on both ends increase and on seal section and shoulder zone slightly change. The maximum stress on some thread exceed the yield limit of material when axial tensile loads exceed 400KN. Limited axial tensile loads sharply influence the contact pressures on shoulder zone while slightly on seal section. Although the maximum contact pressure on shoulder zone drop to 0 when the axial tensile load is 600KN, the maximum contact pressure on seal section will keep on a high level.

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Zheng, Bowen, Shengwen Qi, Xiaolin Huang, Ning Liang e Songfeng Guo. "Compression-Induced Tensile Mechanical Behaviors of the Crystalline Rock under Dynamic Loads". Materials 13, n. 22 (12 novembre 2020): 5107. http://dx.doi.org/10.3390/ma13225107.

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Characterization of the tensile mechanical behaviors of rocks under dynamic loads is of great significance for the practical engineering. However, thus far, its micromechanics have rarely been studied. This paper micromechanically investigated the compression-induced tensile mechanical behaviors of the crystalline rock using the grain-based model (GBM) by universal distinct element code (UDEC). Results showed that the crystalline rock has the rate- and heterogeneity-dependency of tensile behaviors. Essentially, dynamic Brazilian tensile strength increased in a linear manner as the loading rate increased. With the size distribution and morphology of grain-scale heterogeneity weakened, it increased, and this trend was obviously enhanced as the loading rate increased. Additionally, the rate-dependent characteristic became strong with the grain heterogeneity weakened. The grain heterogeneity prominently affected the stress distribution inside the synthetic crystalline rock, especially in the mixed compression and tension zone. Due to heterogeneity, there were tensile stress concentrations (TSCs) in the sample which could favor microcracking and strength weakening of the sample. As the grain heterogeneity weakened or the loading rate increased, the magnitude of the TSC had a decreasing trend and there was a transition from the sharp TSC to the smooth tensile stress distribution zone. The progressive failure of the crystalline rock was notably influenced by the loading rate, which mainly represented the formation of the crushing zone adjacent to two loading points. Our results are meaningful for the practical engineering such as underground protection works from stress waves.

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Patel, Vinay Kumar, e Komal Rani. "Mechanical and Wear Properties of Friction Stir Welded 0–6Wt% nAl2O3 Reinforced Al-13Wt%Si Composites". Strojnícky casopis – Journal of Mechanical Engineering 67, n. 1 (1 aprile 2017): 77–86. http://dx.doi.org/10.1515/scjme-2017-0008.

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Abstract Friction Stir Welding (FSW) of an Al-13%Si alloy matrix reinforced with 0, 3 and 6 wt% Al2O3 nanoparticles (nAl2O3) is performed and the optical microstructures, tensile strength, hardness and sliding wear properties of friction stir welded joints are investigated and compared to those of base materials. Four different zones of distinct appearances were observed during FSW, which exhibited altered microstructures in the nugget zone (NZ), thermo mechanically affected zone (TMAZ), heat affected zone (HAZ), and base material zone (BMZ). The ultimate tensile strength of the base materials and their welded joints were found to be increasing with increased wt% of nano-alumina reinforcements. High joint efficiency of 89-97% was achieved in FSW. Hardness and wear resistance of friction stir welded joints were found to be better than those of the base materials.

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26

Zuo, Yu Jun, Chun An Tang, Wan Cheng Zhu e Lian Chong Li. "Influence of Duration of Stress Wave on the Spallation Process in Inhomogeneous Material". Key Engineering Materials 353-358 (settembre 2007): 917–20. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.917.

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Based on mesoscopic damage mechanics, a numerical code RFPA2D (dynamic version) is developed to simulate the spallation process of inhomogeneous medium induced by reflection of stress wave, and the influence of duration of stress wave on spallation is discussed. For convenience of description and discussion, the failure area in the immediate vicinity of loading position of model is divided into two zones, i.e. comminution zone and fracture zone; and the failure area caused by spalling in model is defined as spalling zone. The comminution zone is affected little by the duration of stress wave, but the fracture zone and the spalling zone are affected to a greater extent by duration, also, the stability of specimen is affected by the duration of stress wave. Furthermore, if the duration becomes significantly long, the fracture zone corresponding to the maximum extension of the radial tensile cracks will be dominant in specimen. If the duration of stress wave becomes short to some extent, the spalling zone corresponding to the maximum extension of the tangential tensile cracks will be dominant in specimen. In addition, if the duration of stress wave is long enough, the specimen may lose stability.

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27

Ahmed, Talha, Wali Muhammad, Mustasim Billah Bhatty, Ahnaf Usman Zillohu e Hamid Zaigham. "Optimization of Maximum Tool Travel Speed for Friction Stir Welded AA-2014-T6 without Compromising the Mechanical Properties". Key Engineering Materials 875 (febbraio 2021): 219–26. http://dx.doi.org/10.4028/www.scientific.net/kem.875.219.

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Abstract (sommario):

In this study optimization of maximum travel speed that can be achieved for Friction Stir Welding of Aluminum Alloy 2014-T6 without compromising the mechanical properties was carried out. Joints were made at different travel speeds of 200, 300, 400, 500 and 600 mm/min with constant tool rotational speed of 800 rpm and tool tilt angle of 2.The samples were characterized by stereo microscopy, optical microscopy, scanning electron microscopy, Vickers microhardness testing and tensile testing. Microstructural features of as-welded samples revealed refined equiaxed grains in nugget zone and grain growth in the heat effected zone. Tensile test results showed that the tensile strength was maximum at travel speed of 500 mm/min but then decreased after further increasing the travel speed. Hardness in the nugget zones of all welds was lower than that of base material. Fractographic analysis exhibited significant variations in fracture surfaces of tensile samples. A relationship between the welding parameters and resultant heat inputs was also discussed.

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28

Cui, Maomao, Zhao Wang, Leigang Wang e Yao Huang. "Numerical Simulation and Multi-Objective Optimization of Partition Cooling in Hot Stamping of the Automotive B-Pillar Based on RSM and NSGA-II". Metals 10, n. 9 (18 settembre 2020): 1264. http://dx.doi.org/10.3390/met10091264.

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Abstract (sommario):

In this study, the simulation and optimization of the partition cooling in the hot stamping process was carried out for an automotive B-pillar through minimizing the maximum thickening rate and the maximum thinning rate located in the rapid and slow cooling zones. The optimization was implemented by investigating the process parameters such as friction coefficient, sheet austenitizing temperature, holding time, heating zone temperature, the upper binder force and the lower binder force. The optimal Latin hypercube design (OLHD), the response surface methodology (RSM) and the non-dominated sorting genetic algorithm (NSGA-II) were combined to establish the relationship between process parameters and form quality objectives. After multi-objective optimization, the maximum thickening rate and the maximum thinning rate of the slow cooling zone and rapid cooling zone were 11.1% and 12.4%, 4.7% and 7.1%, respectively. Afterwards, the simulation was performed according to the optimized parameter combinations to analyze the temperature field, microstructure, tensile strength, hardness, thickening rate and thinning rate, and forming quality. Moreover, the hot stamping test and experimental results showed that the microstructure of the ferrite and pearlite structure was uniformly distributed in the slow cooling zone, and its tensile strength reached 680 MPa, the elongation was 11.4% and the hardness was 230.56 HV, while the lath martensite structure was obtained in the rapid cooling zone, with tensile strength of up to 1390 MPa, elongation of about 7.0% and hardness reaching 478.78 HV. The results of thickness, microstructure, tensile strength and the hardness test correspond well with the simulation results.

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29

Denesh, Mr K. C., e V. Senthilkumar. "Experimental Study on The Steel Fiber Reinforcement Concrete". International Journal for Research in Applied Science and Engineering Technology 11, n. 1 (31 gennaio 2023): 710–13. http://dx.doi.org/10.22214/ijraset.2023.48670.

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Abstract (sommario):

Abstract: Concrete is one of the world most widely used construction material. However, since the early 1800’s, it has been known that concrete is weak in tension. Weak tensile strength combined with brittle behavior result in sudden tensile failure without warning. This is obviously not desirable for any construction material. Thus, concrete requires some form of tensile reinforcement to compensate its brittle behavior and improve its tensile strength and strain capacity to be used in structural applications. Historically, steel has been used as the material of choice for tensile reinforcement in concrete. Unlike conventional reinforcing bars, which are specifically designed and placed in the tensile zone of the concrete member, fibers are thin, short and distributed randomly throughout the concrete member.

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30

Wang, Feng, Bai Qing Xiong, Yong An Zhang, Hong Wei Liu, Zhi Hui Li, Xi Wu Li e Feng Bin Xia. "Microstructure and Mechanical Properties of Laser Beam Welded AA7021 Aluminum Alloy". Applied Mechanics and Materials 488-489 (gennaio 2014): 106–10. http://dx.doi.org/10.4028/www.scientific.net/amm.488-489.106.

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Abstract (sommario):

In this study, a laser beam welds in a Al-Zn-Mg alloy were characterized by optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and tensile tests. It is found that the joint of the alloy contained three distinctive regions, i.e. fusion zone, heat affected zone and base metal region. The fusion zone consists of small grains, whose size is heterogeneously distributed. Extensive microhardness measurements were conducted in the weld regions of the nuggets exhibited a hardness loss in the fusion zone due to the loss of strengthening phases. Microstructural examination of the joints revealed typical eutectic structure was appeared in the heat-affected zone due to relative low cooling rate. Tensile properties of the joints were obtained by testing flat transverse tensile specimens, and the results indicated that tensile strength of these welds approached 76.8~77.3% of the base metal.

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31

Selig, E. T. "Tensile zone effects on performance of layered systems". Géotechnique 37, n. 3 (settembre 1987): 247–54. http://dx.doi.org/10.1680/geot.1987.37.3.247.

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32

Zaragoci, Jean-François, Luisa Silva, Michel Bellet e Charles-André Gandin. "Numerical tensile test on a mushy zone sample". IOP Conference Series: Materials Science and Engineering 33 (3 luglio 2012): 012054. http://dx.doi.org/10.1088/1757-899x/33/1/012054.

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33

He, En Guang, Li Chen e Ming Tao Wang. "Study on the Microstructure and Property for T-Joints of Al-Li Alloy Welded by Double Sided Synchronization Fiber Laser". Advanced Materials Research 1095 (marzo 2015): 859–64. http://dx.doi.org/10.4028/www.scientific.net/amr.1095.859.

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Abstract (sommario):

In the experiment, the T-joints of 2060-T8/2099-T83 Aluminum-Lithium by double sided synchronization Fiber laser welding with thickness of 2 mm was studied aimed to know the microstructure, the distributions of micro-hardness, and the tensile strength of the T-joints. The results show that the microstructure is columnar fine grain zone, dendrite zone, and equiaxed crystal zone in turn from the weld fusion line to weld centre; the micro-hardness of the weld is lower than the micro-hardness of base metal, and softening phenomenon appears in the weld; The average circumferential tensile strength of T-joints is 423 MPa at room temperature, which reaches the strength of the base metal 82%, the average longitudinal tensile strength of T-joints is 449 MPa, which reaches the strength of the base metal 87%; The fracture of circumferential tensile samples initiates at the weld toe, and breaks in the weld centre or heat affected zone. The fracture of longitudinal tensile samples initiates at varying cross-section, there are dimples in the fracture surfaces of both circumferential tensile samples and longitudinal tensile samples, and the fracture is ductile.

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34

Ma, Chao Qun, Qi Qiang Duan e Xiao Wu Li. "Plastic Deformation and Damage Behavior of AL6XN Super-Austenitic Stainless Steels". Advanced Materials Research 79-82 (agosto 2009): 1951–54. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.1951.

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Abstract (sommario):

Tensile and compressive deformation and damage behaviors of Al6XN super-austenitic stainless steels were examined at different strain rates. The deformation and fracture surfaces were characterized by scanning electron microscopy (SEM). It was found that the uniaxial deformation (tensile or compressive) behaviors of Al6XN stainless steel shows a low strain rate sensitivity over the range of 10-4s-1 - 10-2s-1. The tensile and compressive yield strengths measured are nearly comparable. The steel shows a good tensile plasticity. Dislocation slip deformation is the main characteristic of uniaxial deformation. All fracture surfaces induced by tensile deformation at different strain rates can be divided into two parts, i.e., fibrous zone and shear lip zone. The fibrous zone consists of dimples with a bimodal size.

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35

Wang, Feng, Bai Qing Xiong, Yon Gan Zhang, Hong Wei Liu, Zhi Hui Li e Xi Wu Li. "Effect of Metal Inert Gas Welding on Microstructure and Mechanical Properties of Al-Zn-Mg Alloy". Advanced Materials Research 418-420 (dicembre 2011): 1396–99. http://dx.doi.org/10.4028/www.scientific.net/amr.418-420.1396.

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Abstract (sommario):

Abstract. The microstructure and mechanical properties of a metal inert gas welds in a medium strength Al-4Zn-1Mg alloy were characterized by optical microscope (OM), scanning electron microscope (SEM) and tensile tests. It is found that the joint of the alloy contained three distinctive regions, i.e. fusion zone, heat affected zone and base metal region. Extensive microhardness measurements were conducted in the weld regions of the nuggets exhibited a hardness loss in the fusion zone due to the loss of strengthening phases. Microstructural examination of the joints revealed typical eutectic structure was appeared in the heat-affected zone. Tensile properties of the joints were obtained by testing flat transverse tensile specimens, and the results indicated that tensile strength of these welds approached 83.3~84.2% of the base metal.

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36

Pei, Chao Wu, Yong Yao, Dai Guo Chen, Bin Jia, Li Jun He e Jiu Li Zhang. "Experimental Study of the Tensile Bond Strength in Concrete Aggregate - Paste Interfacial Transition Zone". Applied Mechanics and Materials 193-194 (agosto 2012): 1384–88. http://dx.doi.org/10.4028/www.scientific.net/amm.193-194.1384.

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Abstract (sommario):

Study on the characteristics of tensile bond strength in concrete interfacial transition zone. Calculate the tensile bond strength of interfacial transition zone in concrete by the way of vertical drawing cobblestones of different grain size from C30 concrete by MTS hydraulic loading system .(the grain size include 50,70,90,100mm) results show that:1.when the cobblestones diameter is in a certain range(<90mm in this experiment)or the bonded area is in a certain range(<5251 mm2 in this experiment), The tensile bond strength of concrete interfacial transition zone nothing to do with the cobblestones diameter and the bonding area.2.If the cobblestones diameter or the bonded area is too large, it will affect the bonding effect of the cobblestones and concrete, and cause the depression of tensile bond strength, Therefore , In the actual engineering we should avoid the use of large diameter cobblestones .3. The tensile bond strength of C30concrete interfacial transition zone is approximately 4% - 10% of compressive strength of concrete.

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37

Li, Xiu Hua, Wei Min Cong, Chen Xi Yue e Jian Xiong Liu. "Research on the Technology of GFRP Bars and PC Strand Combined Supporting Piles by Experiment". Advanced Materials Research 838-841 (novembre 2013): 657–60. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.657.

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Abstract (sommario):

GFRP bars and PC strand combination pile that is configuration GFRP bars in the compression zone of the general pile, in the tension zone configuration PC strand. Pile construction is completed and before the excavation, applied partially prestressed for the tension zone of PC strand, so that GFRP bars in tension, with the excavation pit, GFRP bars tendons pulling force gradually reduced; When the excavation to a certain depth, the second prestressed steel strand so until the excavation is completed. In summary, the technology features is GFRP bars, concrete piles, PC strand all in tension. This makes full use of the concrete compression performance, GFRP bars and PC strand tensile good performance characteristics.

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38

Liang, Yan, Yaohui Liu, Yulai Song e Wei Cui. "Optimizing the Mechanical Properties in the Repair Zone of 5Cr5MoV by Controlling Welding Heat Input". Metals 8, n. 12 (23 novembre 2018): 981. http://dx.doi.org/10.3390/met8120981.

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Abstract (sommario):

The influence of welding heat input on the microstructure and mechanical properties of 5Cr5MoV die steel was studied in order to improve the mechanical properties of the cold working die and extend its service life. Shielded metal arc welding (SMAW) method was used with different heat inputs in the range from 4.2 to 6.61 kJ/cm to repair the 5Cr5MoV die steel. Microhardness and tensile properties were performed to evaluate the repaired quality of the cold working die steel. The microhardness of the weld repaired zone gradually decreased from the weld to the tempering zone. The highest microhardness in the weld repaired zone was 863 HV, and finally, it decreased to about 300 HV. With the increase of heat input, the tensile strength of the weld and the heat affected zone increased; nevertheless, the tensile strength of the tempering zone increased first and then decreased. As a result, 6.6 kJ/cm is the best value of heat input judged from the microhardness distribution and the tensile properties.

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39

Wang, Xiao Ming, Sheng Zhu, Zhi Hao Zhao, Qi Wei Wang e Xiao Dong Zhao. "Effect of Micro-Alloyed Treatment for 5183 Welding Wire on Microstructure and Tensile Property of Welded Joint". Applied Mechanics and Materials 633-634 (settembre 2014): 821–25. http://dx.doi.org/10.4028/www.scientific.net/amm.633-634.821.

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Abstract (sommario):

5183 welding wire micro-alloyed using Sc, Zr, Er and automatic MIG welding system applied to weld 7A52 aluminum alloy. Optical microscope and universal tensile testing machine utilized to investigate microstructure and tensile property of welded joint, respectively. The results indicated that welded zone and fused zone was composed of uniform isometric crystal and tiny isometric dendrite crystal when the welded joint was fabricated by using 5183 welding wire micro-alloyed via rare earth element, respectively. Tensile strength and specific elongation of welded zone was improved utmostly when the 5183 welding wire micro-alloyed treatment via single Sc or Zr, respectively. Owing to mirco-alloyed treatment of 5183 welding wire by using Sc, Zr or Er, a large number of Al3Sc, Al3Zr, Al3Er granules had generated in micro-poll, which played heterogeneous nucleation role and refined microstructure of welded zone. Meanwhile, there emerged nanoscaled A13Sc, A13Zr, Al3Er strengthening phase dispersed in welded zone, which had led welded joint to exhibit exclent tensile strength.

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40

Zhao, Tianbo, Yutaka S. Sato, Rongshi Xiao, Ting Huang e Jingquan Zhang. "Laser pressure welding of Al-Li alloy 2198: effect of welding parameters on fusion zone characteristics associated with mechanical properties". High Temperature Materials and Processes 39, n. 1 (27 maggio 2020): 146–56. http://dx.doi.org/10.1515/htmp-2020-0047.

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Abstract (sommario):

AbstractAl-Li alloy 2198 exhibits good combination of toughness and strength but its application is strongly limited by the poor weldability due to the formation of porosities during fusion-welding. This is the first study proposing and verifying a new approach to produce defect-free laser welds of poorly fusion-weldable Al-Li alloy 2198 with applied external pressure, i.e., feasibility of laser pressure welding to Al-Li alloy 2198 was examined. The microstructures associated with tensile shear behavior of laser pressure welded Al-Li alloy 2198 obtained at various welding parameters were analyzed. The results showed that formation of the welding defect in the weld could be successfully suppressed by applying laser pressure welding, even without shielding gas. Three microstructural zones, including the chill zone, the columnar zone and the equiaxed zone were observed in the fusion zone. Size of fusion zone and area fraction of porosities generally increased with increasing roller pressure and welding heat-input, and they dominantly affected the tensile shear behavior, including the peak load and the failure mode, of the weld.

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41

Uzunali, Umut Yaşar, Hamdullah Cuvalcı, Barbaros Atmaca, Serhat Demir e Serdar Özkaya. "Mechanical properties of quenched and tempered steel welds". Materials Testing 64, n. 11 (1 novembre 2022): 1662–74. http://dx.doi.org/10.1515/mt-2022-0047.

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Abstract (sommario):

Abstract Welding is the most commonly used joining process in the industry. Generally, weld zone consists of three different regions such as base metal, heat-affected zone (HAZ) and weld metal (WM). Microstructure of HAZ and WM changes due to the heat effects after the welding process. These effects cause changes in mechanical properties such as Young modulus, tensile strength and hardness in weld zone. The aim of this paper is to identify the mechanical properties of weld zone by uni-axial tensile test, nanoindentation test and hardness test. For this aim, quenched and tempered steel plates were chosen as a test material having high strength. These plates were welded together by flux-cored arc welding method. To determine the effect of weld pass number on the mechanical properties, the weld was completed in single and multi-pass (MP) butt welds separately. For experiments, tensile test specimens were cut by plasma cutting method according to related standard on welded plates. These specimens were subjected to three different post weld heat treatments (PWHT) such as 200 °C, 300 °C and 400 °C to evaluate the hardness change in HAZ. The effect of weld-pass number and PWHT on mechanical properties such as Young modulus, tensile strength and hardness were obtained from WM and HAZ by uni-axial tensile test and nanoindentation test and compared to each other. The yield and ultimate tensile strength of weld zone of welded tensile test specimens (WTTS)-2 is lower than WTTS-1 due to MP welding process. Furthermore, the strain behaviour of weld zone is not affected by PWHT significantly.

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42

Tu, H. Y., Ulrich Weber e Siegfried Schmauder. "Numerical Investigation of the Damage Behavior of S355 EBW by Cohesive Zone Modeling". Advanced Materials Research 1102 (maggio 2015): 149–53. http://dx.doi.org/10.4028/www.scientific.net/amr.1102.149.

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Abstract (sommario):

In this paper, the cohesive zone model is used to study the fracture behavior of an electron beam welded (EBW) steel joint. Mechanical properties of different weld regions are derived from the tensile test results of flat specimens, which are obtained from the respective weld regions. Based on the tensile test of notched round specimens, the cohesive strength T0can be fixed. With the fixed T0value, the cohesive model is applied to compact tension (C(T)) specimens with the initial crack located at different positions of weldment with different cohesive energy values Γ0. Numerical simulations are compared with the experimental results in the form of force vs. Crack Opening Displacement (COD) curves as well as fracture resistance (JR) curves.

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43

Ahn, Young Nam, Min Jung Kang e Cheol Hee Kim. "Analysis of Laser Weldments for Dual-Phase and Martensitic Steel Sheets for Automotive Applications". Defect and Diffusion Forum 353 (maggio 2014): 8–12. http://dx.doi.org/10.4028/www.scientific.net/ddf.353.8.

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Abstract (sommario):

Laser weldability was investigated for advanced high-strength steel sheets for automotive applications. Dual-phase steel (DP780) and martensitic steel (MS1300) sheets were employed as base materials; laser-butt and overlap welding experiments were conducted on combinations of steels with similar and dissimilar strength. The tensile strength and metallurgical morphology were analysed for the butt-welded specimens; tensile-shear strength and bead shapes were analysed for the overlap-welded specimens. Even with laser welding, martensite in the heat-affected zone disintegrated and resulted in a softened, heat-affected zone as compared with the base materials. The tensile strength of a butt weldment was determined by the strength of the heat-affected zone. The tensile-shear strength of an overlap weldment was determined by not only the strength of the heat-affected zone but also bead shapes such as blow holes, underfill, and the bead width at the faying surface.

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44

Li, Zhijun, Zihao Li, Weijie Tang, Shengsheng Zhao e Hongying Wang. "Differences in the Microstructures and Tensile Properties of Each Zone of Inertia Friction Welded Joints of TA19 Titanium Alloy". Processes 11, n. 1 (3 gennaio 2023): 147. http://dx.doi.org/10.3390/pr11010147.

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Abstract (sommario):

TA19 titanium alloy is a novel medium-temperature, high-strength titanium alloy widely used in the aerospace industry, and its welding performance is very important for the manufacturing of structural parts. In this study, TA19 titanium alloy was connected by inertial friction welding (IFW). After welding, the microstructural and alloying elements of the IFW joints were investigated; the results showed that the microstructures of each zone of the IFW joint were different, and accumulations of the β-stable element Mo were only observed in the base metal (BM) and the heat-affected zone (HAZ). Tensile tests were performed using specially designed specimens with circular grooves to obtain the axial mechanical properties of different zones of IFW joints. The stress–strain curves and tensile fractures of the different specimens were analyzed; the results showed that the tensile strength of the welded joint increased, but the plasticity decreased from BM to WZ.

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45

Kosnan, Mohamad Shahrul Effendy, Zaini Ahmad, Abdoulhdi Amhmad Borhana e Mohd Nasir Tamin. "Finite Element Simulation of Ductile Failure Process of Spot Welded Joint under Tensile Loading". Applied Mechanics and Materials 660 (ottobre 2014): 623–27. http://dx.doi.org/10.4028/www.scientific.net/amm.660.623.

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Abstract (sommario):

Deformation response and failure process of a spot welded joint are investigated in this study. For this purpose, a cross-tension spot welded joint sample made of dual phase steel sheets (DP600) is prepared and tensile tested to failure. Complementary FE simulation of the test is performed. The FE model acknowledges the variation of properties across the spot welded region. Rice-Tracey ductile damage model is approximated and employed in the simulation. Close comparison of load-displacement curves and deformed shape with measured values serve as validation of the FE model. Results show that FE simulation with damage-based model adequately predicts tensile deformation and failure of the spot welded joint. Tensile failure of the joint is confined to the heat affected zone and heat affected/fusion zone interface of the joint. Localized through-thickness necking of the sheet metal is captured. In addition, the predicted fracture of the spot welded joint is accompanied by localized extensive plastic deformation.

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46

Wang, X. B. "Distributions of Local Damage Variable and Local Plastic Tensile Strain and Precursors to Failure of Quasi-Brittle Pure Bending Beam". Key Engineering Materials 347 (settembre 2007): 447–52. http://dx.doi.org/10.4028/www.scientific.net/kem.347.447.

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Abstract (sommario):

For many quasi-brittle materials (such as rock, ceramic and concrete) in pure bending state, the material on the tensile side will fail firstly since the compressive strength can be ten times the tensile strength. After tensile strain localization zone is initiated in the midspan of the beam, its propagation direction will be perpendicular to the neutral axis. In the paper, using nonlocal theory or gradient-dependent plasticity, the distributions of local plastic tensile strain and local damage variable in tensile strain localization zone of a pure bending beam are analyzed theoretically. The evolutions of the maximum local plastic tensile strain, the maximum local damage variable and the bending moment with tensile stress acting on the tensile side are presented through examples. The distributions of local plastic tensile strain and local damage variable in tensile strain localization zone are highly nonuniform due to microstructural effect. When the maximum bending moment is reached, the maximum local damage variable is proportional to the ratio of elastic modulus to elastoplastic modulus, while the maximum local plastic tensile strain is inversely proportional to elastic modulus and elastoplastic modulus. For quasi-brittle materials, the elastoplastic modulus that is a constitutive parameter equal to the absolute value of the slope of tensile stress-tensile strain curve in strain-softening stage is much higher. The present theoretical results mean that the precursors to failure are less apparent for extremely brittle materials.

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47

Fan, Hao, Peng Zhou, Jie Li, Jiankang Huang, Yu Ni e Yuanyuan Hui. "Microstructure and Mechanical Properties of Arc Zone and Laser Zone of TC4 Titanium Alloy Laser–TIG Hybrid Welded Joint". Metals 12, n. 11 (30 ottobre 2022): 1854. http://dx.doi.org/10.3390/met12111854.

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Abstract (sommario):

As a high-efficiency and high-quality welding technology, laser-tungsten inert gas (laser–TIG) hybrid welding has been widely used in the aerospace and marine equipment industries. Through laser–TIG hybrid welding of TC4 titanium alloy, the effect of the current on the weld formation, the microstructure and mechanical properties of the arc zone, and the laser zone was studied. The results show that the molten pool in the arc zone will flow periodically, and the flow becomes more intense with an increase in the current, which will result in a finer grain size in the arc zone than in the laser zone, having the effect of eliminating pores. The spacing of the α′ martensite beams in the laser zone is narrower, with an average spacing of 0.41 μm. The β phase increases gradually with the increase in the current, which will lead to a downward trend in the average hardness of both zones. The average hardness value of the laser zone, containing more α′ martensite and less β phase, is slightly higher than that of the arc zone. The hardness uniformity of the laser zone is also significantly better than that of the arc zone. The tensile strength of the joint shows a trend of increasing first and then decreasing, and the joint with I = 50 A presented the highest tensile strength of 957.3 MPa, approaching 100% of the base metal, and fractured in the fusion zone.

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48

Wang, Feng, Yu Ting Zuo, Bai Qing Xiong, Yon Gan Zhang, Hong Wei Liu, Zhi Hui Li e Xi Wu Li. "Effect of Electron Beam Welding on Microstructure and Mechanical Properties of Spray-Deposited Al-Zn-Mg-Cu Alloy". Applied Mechanics and Materials 302 (febbraio 2013): 230–35. http://dx.doi.org/10.4028/www.scientific.net/amm.302.230.

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Abstract (sommario):

In this study, Al-8.6Zn-2.6Mg-2.2Cu (wt,%) alloy was synthesized by the spray atomization and deposition technique. Electron beam welding (EBW) joint in the spray-deposited Al-8.6Zn-2.6Mg-2.2Cu alloy is composed of fusion zone, heat affected zone and base metal region. The microstructure of the fusion zone has been found to be very fine equiaxed grains, and the microstructure of the heat affected zone is mainly composed of α-Al and Al/MgZn2 eutectic microstructure. Extensive microhardness measurements were conducted in the weld regions of the nuggets exhibited a hardness loss in the fusion zone due to the loss of strengthening phases. Tensile properties test results indicated that tensile strength of these welds approached 82.3~85.3% of the base metal. The analysis of fracture surface has confirmed that the specimen fractured within the weld region during tensile test.

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49

Mai, Rong Zhi, Ze Xin Jiang, Jin Jun Ma e Yong Jun Zhang. "Analytical Study on Microstructure and Mechanical Property in HAZ-Softened Weld Joint with High Heat Input of Low Carbon TMCP Steel". Applied Mechanics and Materials 872 (ottobre 2017): 99–106. http://dx.doi.org/10.4028/www.scientific.net/amm.872.99.

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Abstract (sommario):

Three types of low-carbon TMCP steels with different strength of the same carbon equivalent were welded by the flux-cupper back for SAW(FCB) method in this work. The microstructure, hardness and tensile strength of the FCB welded joints were studied. Softening phenomenon occurs in the heat affected zone of low-carbon content and low carbon-equivalent TMCP EH36 steel after high heat input welding. The softened zone is mainly depended on the strength of the base metal (BM), which appears on the fine-grain zone and incomplete crystallize zone of BM with relative low strength, and on the coarse grain zone of BM with high strength. The ratio of the tensile strength between each FCB joint and BM is the same of 0.98 as the same carbon and carbon equivalent content of 0.5% and 0.315% of BM, which is almost independent of the strength of BM. The tensile strength of the incomplete crystallize zone depends on the strength of the BM, which results in the improved strength of the whole softened zone with the increasing strength of base metal.

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Hall, Ernest L., e Ann M. Ritter. "Structure and behavior of metal/ceramic interfaces in Ti alloy/SiC metal matrix composites". Journal of Materials Research 8, n. 5 (maggio 1993): 1158–68. http://dx.doi.org/10.1557/jmr.1993.1158.

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Abstract (sommario):

The structure and mechanical behavior of the fiber/matrix interface in Ti alloy/SCS-6 SiC metal matrix composites were studied. In these composites the interface region consists of a fiber-coating region and a metal reaction zone between the SiC fiber body and the metal matrix. The fiber coating consists of a number of zones or layers which are comprised of cubic SiC particles in a turbostratic carbon matrix. Some ambiguity remains, concerning the number of distinct layers and the size, shape, and density of the SiC particles. The effect of composite fabrication and heat treatment on the coating structure is relatively small. Studies of the metal reaction zone adjacent to the fiber in Ti alloy/SCS-6 SiC MMC's have shown that a number of discrete zones or layers form. Nearest the fiber, a zone of cubic TiC occurs, with increasing grain size with distance from the fiber. Nearest the metal matrix, a zone of Ti5Si3 forms. In high Al content alloys, an intermediate zone forms that consists of Ti2AlC or Ti3AlC. The fiber/matrix interface plays an important role during transverse tensile loading of these composites. The tensile behavior is controlled by debonding at the interface, followed by deformation of the matrix ligaments. Replica observations show that the debonding initiates and propagates within the coating layers, but is not confined to a single layer interface.

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