Weldability study of 304HCu stainless steel using varestraint and “Gleeble” based hot ductility tests

Abstract

The susceptibilities of 304HCu SS to solidification and liquation cracking are assessed in the current work and the underlying mechanisms are clarified. The development of γ + Nb4C3 eutectic along the interdendritic areas in the fusion zone is attributed for solidification cracking in this stainless steel. To forecast and rank the susceptibility of an alloy to solidification cracking, a novel technique is put forth and experimentally confirmed. Using the measured temperature gradient, welding speed and Scheil's solidification module, a relationship between the liquid fraction and mushy zone width is derived. Liquation cracking susceptibility evaluated using “Gleeble™” based hot ductility test is observed to be high which is attributed to the constitutional liquation of primary Nb(C,N) and secondary M23C6 phases present in the base metal. Further, the influence of phosphorus on the local solidus temperature in the partially melted zone of the alloy is discussed in the context of liquation cracking.