Relationship between solidification and liquation cracks in the joining of GTD-111 nickel-based superalloy by Nd:YAG pulsed-laser welding

Abstract

Fusion welding of nickel-based superalloys with a total Al and Ti content of more than 6% has always been challenging. The reason for this is the occurrence of solidification and liquation cracks during welding. Investigating the mechanisms of formation of these two types of cracks can increase the theoretical and practical insight necessary to achieve a welded alloy without cracks. The objective of this research was to look at the link between solidification and liquidation fractures in Nd:YAG pulsed-laser welded GTD-111 nickel-base superalloy joints. The reason for choosing the pulsed-laser method is the mechanism of continuous welding of the pulses and the creation of separate microstructural zones due to the high liquation and solidification speed. Liquation cracks in the partially melted zone (PMZ) of base metal were shown to be significantly associated with solidification cracks in the weld metal, according to the findings. Liquation cracks in PMZ act as a strong place to create and extend solidification cracks. It was also observed that with increasing pulse frequency, the tendency to form both types of cracks decreases due to the increased tendency to back-filling.