Cracking in the Weld Heat-Affected Zone of COntinuously Cast Sheet and Ingot of Ni3Al

Abstract

ABSTRACTWeldability is a key issue for successful applications of ductile Ni3Al in structural components. Here we report the results of an investigation of gas tungsten arc welding behaviors of continuously cast thin sheet and cast ingot of a Ni3Al alloy, known as IC-50, containing boron and zirconium. Cracking in heat-affected zone (HAZ) was prevalent in both types of specimens. Both in cast sheet and ingot, liquation cracking was observed to occur along the grain boundaries in HAZ. Microstructural studies showed that continuously cast thin sheet consisted of columnar grains along the thickness. Easy cracking along the boundaries of columnar grains made cast sheets more susceptible to hot cracking than ingots. The possibility of segregation of boron and zirconium, causing liquation cracking, will be discussed.