Microstructure and Cryogenic Mechanical Properties of a 316L Plate and Its Weldments

Abstract

This paper reports a study to relate microstructure to cryogenic mechanical properties of a 316L plate and its weldments. Both the tensile and fracture toughness test values at 4 K are governed by microstructure that is influenced by the thermo‐mechanical treatment of the materials. The mechanical properties are better when the loading direction is parallel to the rolling directions. 77 K Charpy impact values show much stronger dependence on the orientations than 4 K fracture toughness and tensile test values. This indicates that the anisotropy in microstructure results in much higher anisotropy in fracture mechanisms in dynamic mode than in static mode. Therefore, care has to be taken when one relates the 77 K Charpy impact strength to 4 K fracture toughness. Stress relieve in weldment enhances the fracture toughness and yield strength, but reduces the strain‐hardening rate and ultimate tensile strength.