A study on shrinkage residual stresses,microstructure and mechanical properties of ASS thick pipe welded by GMAW process

Abstract

In this investigation, AISI 304LN austenitic stainless steel pipes having 25mmthickness and 300mminner diameter with conventional and narrowgroove were welded by continuous current gas metal arc welding (GMAW) and pulse current gasmetal arcwelding (P-GMAW) process.Agas tungsten arcwelding (GTAW) processwas used for the welding of the root pass. Microstructural study was carried out in fusion zone (FZ) and heat-affected zone (HAZ).Afavourable microstructure characteristic was observed in the P-GMAW process. The study of transverse shrinkage and shrinkage stresseswere done on the conventional groove with GMAWand P-GMAWprocess and narrow groove by P-GMAWprocess. It was found that narrowgroove weld design with controlledwelding parameters can reduce 45%shrinkage as compare to conventional groove, similarly 30%reduction in shrinkage stress can be achieved.The tensile propertieswere observed to increased, such as yield strengthwas improved from 260MPato 310MPaand ultimate strength was improved from 510MPa to 550MPa in the case of narrow grooveweld by theP-GMAWprocess.