Investigation on the microstructure and mechanical properties analysis of 304L stainless steel multi-pass filler welding joint for pipeline

The multi-pass welding of 45 mm thick 304L stainless steel is carried out by flux-cored wire arc welding. The mechanical property of the welded joint is characterized. Residual stress measurement on the surface of welded joints is carried out by blind hole method. The finite element model of multi-pass welding joint is established based on actual weld morphology. The temperature and stress field have been investigated by the double ellipsoid heat source model during the welding process. The microstructure analysis results show that the upper surface is consist of austenite and ferrite phase, which is larger than the lower weld zone. And the microhardness distribution is shown as welded metal < heat affected zone < base metal. After welding, the maximum longitudinal residual stress is 398 MPa, and the maximum transverse residual stress is 441 MPa.