Effect of low temperature intercritical heat-treatment on stable crack growth behavior in 13% Cr-4% Ni martensitic stainless steel multipass weldments

•J-R curves were characterized for both as-welded and heat-treated materials.•Stable crack extension occurred at a constant J value in the as-welded material.•Intercritical heat-treatment improved strain hardening and crack growth resistance.•TRIP of austenite and tempered martensite retard void nucleation during straining.•Necking was retarded to a 55% higher strain and fracture toughness JIc was doubled. Tension and fracture toughness JIc tests were performed on both as-welded and heat-treated conditions. The softer tempered martensitic matrix and the transformation-induced plasticity (TRIP) of reformed austenite improved significantly the strain hardening behavior of the heat-treated material. These matrix characteristics were found to retard micro-void nucleation during straining. The onset of necking, the elongation at fracture, and the fracture toughness JIc were improved by 55%, 28% and 90%, respectively. These results provide an opportunity to document how the matrix mechanical properties influence the fracture behavior of material which rupture is controlled by the nucleation of micro-voids.