Temperature Dependence of Fracture Behavior and Mechanical Properties of AISI 316 Austenitic Stainless Steel

Abstract

A combination of fractographic and metallographic analysis during tensile tests over the temperature ranging from 20 °C to 750 °C were carried out to investigate the fracture behaviors and deformation modes so as to clarify the temperature dependence of mechanical properties of AISI 316 austenitic stainless steel. Planar slip mode of deformation was observed during tensile tests at 20 °C due to a relatively low SFE (stacking fault energies). Pronounced planar slip characteristics were observed in the range of 350–550 °C, and the resultant localized deformation led to the formation of shear bands. The dislocation cross-slip was much easier above 550 °C, leading to the formation of cell/subgrain structures. The preferential microvoid initiation and subsequent anisotropic growth behavior in the shear bands led to large-size and shallow dimples on the fracture surfaces in the range of 350–550 °C. However, the microvoid tended to elongate along the tensile direction in the localized necking region above 550 °C, resulting in small-size and deep dimples. The shear localization reduced the uniform deformation ability and accelerated the fracture process along shear bands, leading to a plateau in uniform elongation and total elongation in the range of 350–550 °C. The higher capability to tolerate the localized deformation through sustained necking resulted in a significant increase in the total elongation above 550 °C.