Tensile behavior of stainless steel S30408 at the Arctic low temperature

This paper investigated tensile behaviours of S30408 at the Arctic low temperatures (T) of -80~20C. A cooling chamber equipped with liquid nitrogen gas was adopted to rebuild the Arctic low-temperature environment. Standard tension tests were performed on 48 coupons with different thickness at different T values of -80, -60, -30, and 20C. Test results revealed the ductile failure mode of stainless steel S30408 even at -80C. The tensile stress-strain (o-e) curves of S30408 at ambient temperatures exhibited a long strain hardening plateau. Meanwhile, the low-temperature tensile o-e curves of S30408 were different from those at ambient temperatures, which exhibited a second hardening stage with a larger slope than the first hardening. The decreasing T generally increased the elastic modulus, yield and ultimate strength, but reduced the ductility of S30408. Decreasing the T from 20 to -80 reduced the ductility of S30408 by about 28%, but improved the elastic modulus, yield and ultimate strength by about 20%, 22%, and 75%, respectively. This paper also adopted the best subset regression analysis method to develop empirical formulae on estimating influences of T on mechanical properties of S30408. Validations of the predictions by these empirical formulae against the test results in the literature proved their accuracies.