The Relationship between Solidification Mode Ferrite Morphology and Fissuring in Austenitic Stainless Steel Weldments-A Review

A small volume percentage of ferrite in the weldmetal need not necessarily ensure good weldability of austenitic stainless steels. The location and morphology of ferrite in the weldment al is the one which actually plays a major role in hot cracking resistance. This depends on solidification of the alloy and the nature of the solid state ferrite-to-austenite transformation. Added to this impurity elements can alter the relationship between ferrite content and cracking. Both Schaejfler and Delong diagrams predict the amount of retained ferrite in the weldmetal from the alloy chemistry. But both the solidification mode and the rate of cooling to room temperature affect the amount of ferrite retained. These two factors are sensitive to the welding process and welding parameters. Hence concluding about the weldability of austenitic stainless steels, only from compositional consideration is very much inaccurate and dangerous. This paper tries to bring out these aspects clearly by reviewing the essential research work done so far on these lines.