Effect of filler wires on mechanical properties of super-duplex stainless steel UNS S32750 and austenitic stainless steel 304 dissimilar joints welded with PCGTAW technique

Abstract

This study addresses the effects of fillers (ERNiCrMo-3, ERNiCrMo-4 and ER309L) for joining 5 mm dissimilar metals of super-duplex steel (UNS S32750) and austenitic stainless steel (AISI 304) by using pulsed current gas tungsten arc welding. Welding parameters were fixed across all cases with the three alternative filler wires. Mechanical properties of weldments were evaluated by conducting impact, tensile and microhardness tests. Microstructural changes were studied by optical microscopy. The ratio of proof stress to ultimate tensile strength, and the ultimate tensile strength were found to be higher with ERNiCrMo-4 (0.6, 642 MPa) filler weldment than with ERNiCrMo-3 (0.57, 624 MPa) or ER309L (0.56, 612 MPa) filler weldments. Microhardness of the weldment with ERNiCrMo-4 filler was higher than with the other two fillers. It was observed from the impact test results that the ERNiCrMo-4 filler weldment exhibited superior toughness of 189 J.

Keywords

• super-duplex stainless steel
• austenitic stainless steel
• pcgtaw technique
• mechanical properties
• microstructural studies