Investigation of strain aging cracking susceptibility in IN738LC superalloy welded by autogenous TIG welding using numerical modeling

The nickel-based superalloys high sensitivity to various types of cracks during fusion welding and post welding heat treatment, leads to limitations in the repair welding of damaged parts of this material. Strain aging crack is a type of prevalent crack in the IN738LC superalloys that occurs during the post-weld heat treatment, which was investigated in few studies. In this study, using numerical modeling, the susceptibility to strain aging cracking in IN738LC superalloy welded by TIG method without filler metal was investigated. The results of thermal-mechanical modeling as well as experimental evaluation of cross-section of the autogenous welded samples after post-heat treatment showed that the transverse plastic strain of (rather than longitudinal) plastic is a suitable preliminary criterion for evaluating the susceptibility of superalloy to the strain aging cracking and it seems that if the plastic transverse strain is more than 4.6%, the probability of this crack occurring after post weld heat treatment will be very high.