Effect of PWHT on the Carbon Migration and Mechanical Properties of 2205DSS-Q235 LBW Joint

Abstract

The effect of postweld heat treatment (PWHT) on the carbon migration and mechanical properties of the 2205DSS-Q235 laser beam welding (LBW) joint was investigated. The carbon-rich zone (CRZ) and carbon-depleted zone (CDZ) generated at the welding seam/Q235 (WS-Q235) interface as the carbon migration occurred after heat-treated at 600°C, 700°C, and 800°C for 1 h. The softening was found in the CDZ. Only the CRZ in joints heat-treated at 800°C was hardened because of the retaining of high-carbon untempered martensite. The thick CDZ in joints heat-treated at 700°C and 800°C contributed to the tensile fracture and the low elongation. The strength of the joint was roughly determined by the hardness of the fracture zone.