Effects of prestrain on high temperature impact properties of 304L stainless steel
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Chi-Feng Lin National Center for High-Performance Computing, Hsin-Shi Tainan County 744, Taiwan
Tao-Hsing Chen Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan
Meng-Chieh Yang Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, Taiwan (Received 20 August 2009; accepted 16 April 2009)
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 s1 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. I. INTRODUCTION
304L stainless steel is widely used throughout the chemical, machinery, automobile, and nuclear industries, and thus its mechanical properties and fracture mechanisms are of significant interest. The quasi-static mechanical behavior of 304L stainless steel has been widely reported by many investigators.1–3 For example, Semiatin and Holbrook1 studied the isothermal plastic flow behavior of annealed 304L stainless steel in the uniaxial compression and torsional deformation modes at strain rates ranging from 104 to 101 s1 and temperatures in the range 251000 C. Venugopal et al.2 and Sundararaman et al.3 investigated the workability and microstructural evolution of 304L stainless steel at low strain rates. The basic mechanical properties of 304L stainless steel obtained from these studies and others are readily available in material handbooks.4,5 Products fabricated from 304L stainless steel are commonly subjected to impact loads during their service lives. As a result, a detailed knowledge of the impact response of 304L stainless steel is required to ensure the mechanical integrity of such components during their a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2010.0088
754
http://journals.cambridge.org
J. Mater. Res., Vol. 25, No. 4, Apr 2010 Downloaded: 14 Mar 2015
daily use. Stout et al.6 and Harvey et al.7 studied the impact behavior of 304L stainless steel by performing splitHopkinson pressure bar (SHPB) experiments and Charpy tests, respectively. However, the impact performance of 304L stainless steel is affected not only by the loading rate, but also by the test temperature and the specimen defo
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