Understanding serrated grain boundaries in the context of strength-toughness combination in ultrahigh-strength maraging steel

Abstract

Grain boundary serration generally occurs in the presence of grain boundary precipitates and has significant impact on mechanical properties. In this regard, the observation of serrated grain boundaries in ultrahigh strength and high fracture toughness maraging steel is revisited, and the mechanism of grain boundary serration during heat treatment is discussed. It is proposed that the prior presence of continuous precipitates along the grain boundaries restricts the mobility of grain boundaries, which leads to their serration. The serrated grain boundaries are envisaged to arrest and/or deflect the growth and propagation of crack leading to high fracture toughness in ultrahigh strength maraging steel.