The Experts below are selected from a list of 1731 Experts worldwide ranked by ideXlab platform
Z F Zhang - One of the best experts on this subject based on the ideXlab platform.
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revisiting the role of Prestrain history in the mechanical properties of ultrafine grained cocrfemnni high entropy alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2021Co-Authors: S J Sun, Y Z Tian, Z F Zhang, H R Lin, Zhitai WangAbstract:Abstract The yield strength of face-centered cubic (FCC) alloy is always insufficient for applications. In this work, different Prestrain histories were imposed to improve the yield strength and strain-hardening capability of an ultrafine-grained (UFG) CoCrFeMnNi high-entropy alloy (HEA). In contrast to the specimens Prestrained at 293 K, the specimens Prestrained at 77 K possess higher yield strength, elongation, and strain-hardening capability, which were intensely related to the formation of deformation twins. The cryogenic strengthening magnitude is found to be strongly associated with the grain size, but slightly affected by dislocations. By modulating the Prestrain history, an ultrahigh yield strength of 1.84 GPa and a considerable uniform elongation of 13% were achieved at 77 K in the CoCrFeMnNi HEA. Hence, imposing Prestrain on HEAs at 77 K could be an efficient strategy to harmonize the mechanical properties of the FCC HEAs, which would enrich the application of HEAs in cryogenic fields.
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modulating the Prestrain history to optimize strength and ductility in cocrfemnni high entropy alloy
Scripta Materialia, 2019Co-Authors: S J Sun, Y Z Tian, Hui Lin, H J Yang, Z F ZhangAbstract:Abstract CoCrFeMnNi high-entropy alloy (HEA) exhibits excellent combination of strength and ductility, but low yield strength. In order to ameliorate the mechanical properties, Prestrain was applied in this work. The HEA Prestrained at 77 K possesses higher yield strength and uniform elongation than the HEA Prestrained at 293 K, indicating that the trade-off relationship between strength and ductility can be broken by modulating the Prestrain history. Furthermore, the yield point phenomenon was disappeared after Prestrained at 77 K. This can be related to the density and distribution of dislocations as imposed in the Prestrain process at 293 K and 77 K.
S J Sun - One of the best experts on this subject based on the ideXlab platform.
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revisiting the role of Prestrain history in the mechanical properties of ultrafine grained cocrfemnni high entropy alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2021Co-Authors: S J Sun, Y Z Tian, Z F Zhang, H R Lin, Zhitai WangAbstract:Abstract The yield strength of face-centered cubic (FCC) alloy is always insufficient for applications. In this work, different Prestrain histories were imposed to improve the yield strength and strain-hardening capability of an ultrafine-grained (UFG) CoCrFeMnNi high-entropy alloy (HEA). In contrast to the specimens Prestrained at 293 K, the specimens Prestrained at 77 K possess higher yield strength, elongation, and strain-hardening capability, which were intensely related to the formation of deformation twins. The cryogenic strengthening magnitude is found to be strongly associated with the grain size, but slightly affected by dislocations. By modulating the Prestrain history, an ultrahigh yield strength of 1.84 GPa and a considerable uniform elongation of 13% were achieved at 77 K in the CoCrFeMnNi HEA. Hence, imposing Prestrain on HEAs at 77 K could be an efficient strategy to harmonize the mechanical properties of the FCC HEAs, which would enrich the application of HEAs in cryogenic fields.
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modulating the Prestrain history to optimize strength and ductility in cocrfemnni high entropy alloy
Scripta Materialia, 2019Co-Authors: S J Sun, Y Z Tian, Hui Lin, H J Yang, Z F ZhangAbstract:Abstract CoCrFeMnNi high-entropy alloy (HEA) exhibits excellent combination of strength and ductility, but low yield strength. In order to ameliorate the mechanical properties, Prestrain was applied in this work. The HEA Prestrained at 77 K possesses higher yield strength and uniform elongation than the HEA Prestrained at 293 K, indicating that the trade-off relationship between strength and ductility can be broken by modulating the Prestrain history. Furthermore, the yield point phenomenon was disappeared after Prestrained at 77 K. This can be related to the density and distribution of dislocations as imposed in the Prestrain process at 293 K and 77 K.
Chi Feng Lin - One of the best experts on this subject based on the ideXlab platform.
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effects of Prestrain and strain rate on dynamic deformation characteristics of 304l stainless steel part 2 microstructural study
Materials Science and Technology, 2002Co-Authors: Woei-shyan Lee, Chi Feng LinAbstract:AbstractThe morphologies and characteristics of microstructure, including dislocations, mechanical twins and α' martensite, in 304L stainless steel deformed under various strain, strain rate range from 102 to 5 × 103 s-1 for different Prestrain levels at room temperature were examined by a split Hopkinson bar and TEM. The evolution of microstructure correlated with dynamic mechanical behaviour are presented and discussed in terms of Prestrain and applied strain rate. The results show that characteristics of dislocations, mechanical twins and α' martensite varied with Prestrains, strains and strain rates. They dominate the strengthening effects on the 304L stainless steel. Dislocation cell structures can be observed in all tested specimens. At larger Prestrain under dynamic loading, the formation of elongated dislocation cells becomes evident. The presence of elongated dislocation cells leads to different work hardening behaviour. Twinning occurred at all testing conditions except for the 0·15 Prestrain sp...
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effects of Prestrain and strain rate on dynamic deformation characteristics of 304l stainless steel part 1 mechanical behaviour
Materials Science and Technology, 2002Co-Authors: Woei-shyan Lee, Chi Feng LinAbstract:AbstractA split Hopkinson bar is used to investigate the effects of Prestrain and strain rate on the dynamic mechanical behaviour of 304L stainless steel, and these results are correlated with microstructure and fracture characteristics. Annealed 304L stainless steel is Prestrained to strains of 0·15, 0·3, and 0·5, then machined as cylindrical compression specimens. Dynamic mechanical tests are performed at strain rates ranging from 102 to 5 × 103 s-1 at room temperature, with true stains varying from 0·1 to 0·3. It was found that 304L stainless steel is sensitive to applied Prestrain and strain rate, with flow stress increasing with increasing Prestrain and strain rate. Work hardening rate, strain rate sensitivity, and activation volume depend strongly on the variation of Prestrain, strain, and strain rate. At larger Prestrain and higher strain rate, work hardening rate decreases rapidly owing to greater heat deformation enhancement of plastic flow instability at dynamic loading. Strain rate sensitivity ...
Woei-shyan Lee - One of the best experts on this subject based on the ideXlab platform.
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Effects of Prestrain on high temperature impact properties of 304L stainless steel
Journal of Materials Research, 2010Co-Authors: Woei-shyan Lee, Chi-shyan Lin-shyan, Tao-shyan Chen-shyan, Meng-shyan YangAbstract:The effects of Prestrain, strain rate, and temperature on the impact properties of 304L stainless steel are investigated using a compressive split-Hopkinson pressure bar. The impact tests are performed at strain rates ranging from 2000 to 6000 s^−1 and temperatures of 300, 500, and 800 °C using 304L specimens with Prestrains of 0.15 or 0.5. The results show that the flow stress, work-hardening rate, and strain rate sensitivity increase with increasing strain rate or decreasing temperature. As the Prestrain increases, the flow stress and strain rate sensitivity increase, but the work-hardening rate decreases. The temperature sensitivity increases with an increasing strain rate, temperature, and Prestrain. Overall, the effects of Prestrain on the impact properties of the tested specimens dominate those of the strain rate or temperature, respectively. Finally, optical microscopy observations reveal that the specimens fracture primarily as the result of the formation of adiabatic shear bands.
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effects of Prestrain and strain rate on dynamic deformation characteristics of 304l stainless steel part 2 microstructural study
Materials Science and Technology, 2002Co-Authors: Woei-shyan Lee, Chi Feng LinAbstract:AbstractThe morphologies and characteristics of microstructure, including dislocations, mechanical twins and α' martensite, in 304L stainless steel deformed under various strain, strain rate range from 102 to 5 × 103 s-1 for different Prestrain levels at room temperature were examined by a split Hopkinson bar and TEM. The evolution of microstructure correlated with dynamic mechanical behaviour are presented and discussed in terms of Prestrain and applied strain rate. The results show that characteristics of dislocations, mechanical twins and α' martensite varied with Prestrains, strains and strain rates. They dominate the strengthening effects on the 304L stainless steel. Dislocation cell structures can be observed in all tested specimens. At larger Prestrain under dynamic loading, the formation of elongated dislocation cells becomes evident. The presence of elongated dislocation cells leads to different work hardening behaviour. Twinning occurred at all testing conditions except for the 0·15 Prestrain sp...
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effects of Prestrain and strain rate on dynamic deformation characteristics of 304l stainless steel part 1 mechanical behaviour
Materials Science and Technology, 2002Co-Authors: Woei-shyan Lee, Chi Feng LinAbstract:AbstractA split Hopkinson bar is used to investigate the effects of Prestrain and strain rate on the dynamic mechanical behaviour of 304L stainless steel, and these results are correlated with microstructure and fracture characteristics. Annealed 304L stainless steel is Prestrained to strains of 0·15, 0·3, and 0·5, then machined as cylindrical compression specimens. Dynamic mechanical tests are performed at strain rates ranging from 102 to 5 × 103 s-1 at room temperature, with true stains varying from 0·1 to 0·3. It was found that 304L stainless steel is sensitive to applied Prestrain and strain rate, with flow stress increasing with increasing Prestrain and strain rate. Work hardening rate, strain rate sensitivity, and activation volume depend strongly on the variation of Prestrain, strain, and strain rate. At larger Prestrain and higher strain rate, work hardening rate decreases rapidly owing to greater heat deformation enhancement of plastic flow instability at dynamic loading. Strain rate sensitivity ...
B. Yan - One of the best experts on this subject based on the ideXlab platform.
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effect of Prestrain paths on mechanical behavior of dual phase sheet steel
International Journal of Fatigue, 2009Co-Authors: Hong Tae Kang, Ghassan T. Kridli, A. Khosrovaneh, B. YanAbstract:Abstract The tensile and fatigue performance of dual phase (DP600) sheet steel was investigated with specimens, as-received, and with two different Prestrain path conditions, uniaxial and plane strain. First, tensile tests of the as-received condition of DP600 were performed to obtain mechanical properties, specifically the uniform elongation, for determining the Prestrain levels of the specimens. Then three Prestrain levels from each strain path were applied onto the sheet steel. Tensile and fatigue specimens were prepared from the Prestrained coupons. Mechanical properties were obtained from the uniaxial tests of the as-received and Prestrained specimens for comparison. Fatigue testing was also conducted with strain controlled to acquire fatigue properties. The fatigue life curves were plotted as a function of strain range and Neuber factor. The uniaxially Prestrained specimens exhibited higher fatigue strength than that of the as-received ones for the long life region, but the opposite effect was observed for the short life region of less than 104 reversals.
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Modified strain-life equation to consider the effect of different Prestrain paths for dual phase sheet steel
Journal of Materials Processing Technology, 2009Co-Authors: Hong Tae Kang, Ghassan T. Kridli, A. Khosrovaneh, B. YanAbstract:Fatigue tests of dual phase sheet steel (DP600) were conducted with strain controlled mode of fully reverse loading conditions at room temperature. The specimens were fabricated with three different Prestrain paths such as as-received, uniaxial Prestrain and plane strain Prestrain. Fatigue properties for the all Prestrain paths were determined from the fatigue test results. The strain-life curve equations were depended on the Prestrain levels and paths. In this study a universal strain-life equation was proposed based on the experimental data to predict the fatigue life of dual phase sheet steel with different Prestrain paths. The proposed model utilized fatigue properties of the as-received condition coupled with Prestrain levels in the length, width, and thickness of the test specimen. The effectiveness of the proposed universal strain-life equation was demonstrated with a simple metal formed part that experienced various Prestrain paths.
