Investigation on Mechanical Properties of S30403 Austenitic Stainless Steel at Different Temperatures

In order to study the influence of cryogenic temperature on the mechanical properties, a series of uniaxial tensile experiments were performed at different temperatures (20 °C, 0 °C, −20 °C, −40 °C, −80 °C, −120 °C, −196 °C) for the austenitic stainless steel S30403 (both the base material and weld joint). $Rp0.2$ (0.2% proof strength), $Rp1.0$ (1% proof strength), $Rm$ (tensile strength), $A$ (elongation after fracture), $Z$ (reduction of area), $σcr$ (a critical threshold stress for onset of discontinuous yielding), and $Rh$ (second hardening ratio, $Rm/σcr$⁠) were taken into consideration. It was found that in GB150, ASME VIII-1, and EN13445, the maximum allowable stress for austenitic stainless steel at low temperature (≤20 °C) was dependent on the yielding strength at room temperature (20 °C). Compared with $Rp0.2$⁠, $Rp1.0$ had a linear relationship with temperature. Synthetically considering the first hardening and the second hardening, both the base material and weld joint presented a better strength performance at low temperatures. The plasticity of base material dropped as the temperature decreased, and it was kept at an acceptable level. Nonetheless, the plasticity of weld joint was nonlinear because of the nonuniform structure components.