Effects of Laves phase precipitation embrittlement and its dissolution kinetics in super-ferritic stainless steels on the ductile-brittle transition

This study simulated the Laves phase precipitation embrittlement of super-ferritic stainless steels (SFSSs). The dissolution kinetics of the Laves phase, grain coarsening, and their effects on the mechanical properties and ductile-brittle transition during dissolution heat treatment were subsequently studied. The Laves phase dissolution adhered to the Johnson-Mehl-Avram-Kolmogorov variation expression, exhibiting an activation energy of approximately 368 kJ mol−1. High-temperature reheating (1100 °C) resulted in severe grain coarsening, leading to brittle fracture. A dissolution treatment of only 0.5 h at 1050 °C resulted in a high yield strength of 407.8 MPa, large elongation of 29.6%, and impact toughness of 237.2 J/cm2 because the entirety of the Laves phase was dissolved and no obvious grain growth was observed. This indicates that dissolution heat treatment is a simple and feasible method for recovering the ductility and toughness of Laves phase precipitation-embrittled SFSSs.