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

•We tested crater, weld-seam solidification, and heat-affected-zone liquation cracks.•Factors and regions were examined for multi-pass/multi-layer welding hot cracking.•Decreasing welding joint macro/microsegregation were studied to control hot cracks.•Phase transition, thermodynamic properties, and thermal stress were modeled. 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.