Creep-rupture properties of 50mm thick 304 stainless steel joints by narrow-gap submerged arc welding were investigated at 550°C using small (round bar) and large (full-thickness plate) specimens. For the small round-bar specimens rupture occurred at the base metal, while fracture was at the weld metal for large plate specimens. This difference in rupture location was attributed to the stress distribution in the welded joint specimens during the creep process. The stress distribution can be caused by the non-uniformity of strength in the weld metal and the suppression of deformation due to hardening of the heat affected zone in the base metal.
The deformation behaviors of base metal and weld metal in the joint can be estimated by a FEM computation, and it allow us to predict the location of fracture in the weldment by comparison of relafive strength with base and weld metals.
