Influence of post-weld solution treatment on mechanical properties and microstructure of fusion zone of cobalt free maraging steel weldment

Abstract

Post-weld solution treatment (PWST) was carried out on gas tungsten arc weldments of a cobalt free maraging steel. A substantial increase in fusion zone toughness was observed after PWST. It was established that the increase in fusion zone toughness was due to a reduction in austenite content of the fusion zone. The volume fraction of austenite decreased with increasing solution treatment temperature. The PWST led to a decrease in severity of microsegregation, which in turn caused a reduction in austenite content of the fusion zone. The activation energy for the process of homogenisation of austenite was found to be 265 kJ mol(-1). The present work has clearly demonstrated that PWST before aging improves the fusion zone toughness in cobalt free maraging steel weldments.