Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : October 07, 2017 - October 09, 2017
This paper describes the constitutive modeling of 316 stainless steel subjected to thermo-mechanical cyclic loading. To this end, thermo-mechanical and isothermal cyclic experiments with strain holding were performed at temperatures ranging from 200 °C to 800 °C. It was observed that cyclic hardening and stress relaxation under thermo-mechanical cyclic loading were significantly affected by such physical mechanisms as dynamic strain aging and thermal recovery, which noticeably occurred at temperatures around 500 °C and higher than 700 °C, respectively, in the isothermal experiments. The thermo-mechanical and isothermal cyclic experiments were then simulated using a constitutive model, in which mechanical strain was decomposed into elastic, viscoplastic, and creep parts. Combined isotropic-kinematic hardening was considered for the viscoplasic part, while Norton’s law was simply assumed for the creep part. A cyclic hardening parameter was introduced so as to affect not only isotopic but also kinematic hardening for the viscoplastic strain rate. The creep parameters were determined by fitting the stress relaxation data under strain holding. By performing the simulation with focus on the saturated state of cyclic hardening, the constitutive model was shown to reproduce well the hysteresis loops and stress relaxation curves in the thermo-mechanical cyclic experiments if the cyclic hardening and creep parameters were assumed to be dependent on the maximum temperature in each experiment.
