Controlling hot cracking in Ni-based Inconel-718 superalloy cast sheets during tungsten inert gas welding

The pre-welding condition of the base metal, the welding heat input, and the state of the interlayer in multi-layer welding are examined to identify means of controlling the hot cracking in Inconel-718 cast sheets during tungsten inert gas (TIG) welding. A finite element method (FEM) incorporating the cast microstructure and alloy chemical composition was used to calculate the welding stresses and predict crack initiation. The crater crack, weld-seam center longitudinal solidification crack, and the weld toe compound crack mixed with the transversal solidification crack and the heat-affected zone (HAZ) liquation crack are discussed. A pre-welding homogenization heat treatment, lower welding heat input, and post-welding crater grinding of each individual welding seam can decrease its hot cracking susceptibility.