Self-Hearing of High Temperrature Damage and Improvement of High Temperature Properties of 304 Stainless Steel

Abstract

Long time creep fracture of austenite stainless steels is caused by the initiation and growth of creep voids at grain boundaries during creep. Present work was intended to propose a healing process for the creep voids and improve the creep rupture properties. Addition of B, N and Ti and also removal of S in a 304 stainless steel promoted the precipitation of BN at surface of creep voids. The modified steel showed high rupture strength and high rupture ductilities, and it was confirmed that boronnitride precipitates at creep void surface in the steel. It was thought that the boronnitride at creep void surface suppresses creep void growth and improvecreep upture properties by the self-healing effect on creep voids.