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CSME 2023/12
Volume 44 No.6
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555-564
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Effects of Strain Rate and Temperature on Deformation Behaviour and Microstructural Evolution of Powder Metallurgical High-speed Steel (ASP 60) Part 1 – Mechanical Behaviour
Woei-Shyan Leea and Ting-Ju Chenb
aDepartment of Mechanical Engineering, National United University, Miaoli, Taiwan 360302, ROC.
bDepartment of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan 70101, ROC.
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Abstract:
The mechanical behaviour and microstructural evolution of high alloyed powder metallurgical high-speed steel ASP 60 are investigated under quasi-static and dynamic loads using an MTS 810 test machine and compressive split-Hopkinson pressure bar, respectively. The tests are performed at strain rates of 1.0×10-3, 1.0×10-1, 1.0×100, 2.5×103, 4.0×103 and 6.0×103 s-1 at temperatures of -195°C, 25°C, 400°C and 800°C, respectively. The effects of the strain rate and temperature on the evolution of the specimen microstructure are evaluated using optical microscopy and scanning electron microscopy. The strain rate and temperature are both shown to have a significant effect on the flow stress, work hardening behaviour, strain rate sensitivity, temperature sensitivity, and fracture mechanism. A negative strain rate sensitivity is observed at extremely high and extremely low temperatures during dynamic impacts due to the high interfacial area of the powder particles which constitute the ASP 60 microstructure. The fracture morphologies of the different specimens reveal a brittle and ductile fracture mechanism, which varies depending on the strain rate and temperature.
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Keywords: split-Hopkinson pressure bar, quasi-static state, work hardening, negative strain rate sensitivity, SEM fracture mechanism
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*Corresponding author; e-mail:
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©
2023
CSME , ISSN 0257-9731
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