Superiority of Narrow Gap SMA Welding of 304 in Stainless Steel Pipe

Shielded metal arc (SMA) welding of 25mm thick wall 325mm O.D, 304LN austenitic stainless steel pipe has been carried out with GTAW ischolar_main pass by using conventional V-groove and narrow groove welding techniques at appropriately designed WPS to produce sound weld of significantly narrow weld groove. The characteristics of the narrow groove weld joints with respect to their weld size, microstructure, residual stresses, mechanical properties and corrosion susceptibility have been studied and compared to those of the conventional V-groove weld joints. It is observed that the use of narrow groove instead of conventional V-groove in welding of thick wall stainless steel pipe is beneficial especially with respect to reduction in grain coarsening at HAZ adjacent to the fusion line and lowering of residual stresses of weld joint by keeping the mechanical properties and susceptibility to IGC comparable to those of the V-groove weld joint. However the inclusion content of the narrow groove SMA weld has been found comparatively higher than that of the conventional V-groove weld.