Analysis and mathematical modelling of elevated temperature flow behaviour of austenitic stainless steels

High temperature flow behaviour of various grades of austenitic stainless steels viz. 304L, 304, 304 (as-cast), 316L and 15Cr–15Ni–Ti modified austenitic stainless steels (alloy D9) were analyzed by performing isothermal hot compression tests in a wide range of temperatures (1073 K to 1473 K for 304L, 304, 304 (as-cast), 316L and 1123 K to 1523 K for alloy D9) and strain rates (0.001–1 s−1). It has been observed that all these materials show strain hardening, strain rate hardening, thermal softening, coupled effect of temperature and strain, and temperature and strain rate on flow stress in the hot working domain. The modified Zerilli–Armstrong (MZA) model which considers the above significant effects on flow stress has been applied to predict the flow behaviour of these materials. The material constants of the MZA model for each material have been evaluated and subsequently applied to predict the flow stress. It has been demonstrated that the MZA model could adequately represent the elevated temperature flow behaviour of these materials over the entire ranges of strain, strain rate and temperature.

Research highlights▶ Constitutive analysis of various austenitic stainless steels was performed. ▶ The materials show strain hardening, strain rate hardening and thermal softening. ▶ They show coupled effect of temperature and strain, and temperature and strain rate. ▶ The modified Zerilli-Armstrong (MZA) model has been applied to predict flow stress. ▶ MZA model could predict the elevated temperature flow behaviour of the materials.