Hot ductility and hot cracking behavior of modified 316 stainless steels designed for high-temperature service

Abstract

The weldability of the modified 316 stainless steel was evaluated by the Gleeble hot ductility test and two hot cracking test methods (Varestraint and Sigmajig). The fusion zone and weld metal heat-affected zone (HAZ) hot cracking susceptibilities of the modified 316 stainless steel are similar to conventional fully austenitic 316 stainless steels and greater than the conventional 316 materials that have a primary ferritic solidification mode. The Gleeble hot ductility test results correlate with the base metal HAZ hot cracking results from the Varestraint test and indicate that the modified 316 materials show a considerably higher base metal HAZ hot cracking susceptibility as contrasted to nuclear grade 316 stainless steels. Varestraint test results and Sigmajig test results and Sigmajig test results for the tested materials showed good correlations. The sensitivity of the base metal to HAZ liquation cracking has been successfully predicted by using a newly developed hot ductility criterion, the ratio of ductility recovery (RDR). An excellent correlation between the Gleeble Test criterion RDR and the Varestraint Test criteria (TCL, MCL and CHL) has been found.