Strength and Fracture Toughness of Type 304 and 316 Austenitic Stainless Steels at 4.2 K

Abstract

The tensile properties and fracture toughness of type 304L, 316L and 316LN austenitic stainless steels and their weldments at cryogenic temperatures have been summarized in the literature. Rolled plates showed a trade-off relationship between 0.2% proof stress and planestrain fracture toughness with those at 4.2 K. The 0.2% proof stress increases with increasing C+N content, and the fracture toughness depends on their austenite stability to α’-martensitic transformation at the crack tip. The formation of shear bands at low strains is directly related to fracture toughness. The stacking fault energy represents the shear-band formation as well as slip deformation manner, so alloy design with higher Ni, Mn, and Mo contents in the chemical composition range of 316LN would be desirable to improve fracture toughness due to higher stacking fault energy.