Deformation behavior of a 16-8-2 GTA weld as influenced by its solidification substructure

Weldment sections from 'formed and welded’ type 316 stainless steel pipe are characterized with respect to some time-independent (tensile) and time-dependent (creep) mechanical properties at temperatures between 25 °C and 649 °C. The GTA weldment, welded with 16-8-2 filler metal, is sectioned from pipe in the ‘formed + welded + solution annealed + straightened’ condition, as well as in the same condition with an additional ‘re-solution’ treatment. Detailed room temperature microhardness measurements on these sections before and after reannealing enable a determination of the different recovery characteristics of weld and base metal. The observed stable weld metal solidification dislocation substructure in comparison with the base metal ‘random’ dislocation structure, in fact, adequately explains weld/base metal elevated temperature mechanical behavior differences from this recovery characteristic standpoint. The weld metal substructure is the only parameter common to the variety of austenitic stainless steel welds exhibiting the consistent parent/weld metal deformation behavior differences described here. As such, it must be considered the key to understanding weldment mechanical behavior.