Tensile properties and fracture behavior of friction stir welded joints of Fe-32Mn-7Cr-1Mo-0.3N steel at cryogenic temperature

This study investigates the cryogenic tensile properties and fracture behavior of fiction stir welded and post-weld heat-treated joints of 32Mn-7Cr-1Mo-0.3N steel. Cryogenic brittle fracture, which occurred in the as-welded joint, is related to the residual particles that contain tungsten in the joint band structure. Post-weld water toughening resulted in the cryogenic intergranular brittleness of the joint, which is related to the non-equilibrium segregation of solute atoms during the post-weld water toughening. Annealing at 550 °C for 30 min can effectively inhibit the cryogenic intergranular brittleness of the post-weld water-toughened joint. The yield strength, ultimate tensile strength, and uniform elongation of the annealed joint are approximately 95%, 87%, and 94% of the corresponding data of the base metal.