Abstract:
The mechanical properties of stainless steel material at elevated temperatures are the key parameters for fire resistant design and numerical simulation analysis of stainless steel structures. Compared with carbon steel, stainless steel is an anisotropic material, with a stronger nonlinearity, a lower proportionality limit, and apparent strain-hardening, as well as having no obvious yield plateau. There were significant differences in the mechanical properties of the two materials at elevated temperatures. Based on MTS810 material testing system, tests at room temperature and steady and transient state tests at elevated temperatures were conducted on the mechanical properties of S30408 austenitic stainless steel. The test results were compared with European Code and other existed research results of stainless steel material. The parameters which influence (such as hardening indexes
nθ and
mθ ) the mechanical properties of stainless steel material at elevated temperatures were modified using the results of the steady state test. An expression of the constitutive relationship of stainless steel was proposed. The reduction factors of initial elasticity modulus, yield strength and ultimate strength at elevated temperatures were presented. By the comparisons between the results of steady state and transient state tests, the stress-strain curves obtained from the two methods slightly differed from each other. The differences were not obvious below 600℃, but the differences increased when temperature was higher than 600℃.