Effect of multi-passes welding on microstructure and properties of austenitic/pearlitic dissimilar steel clad pipe SMAW welded joint

Microstructures of transition weld and melted zone has the important effects on properties of austenitic/pearlitic dissimilar steel clad pipe welded joint.Single-pass and multi-passes welded joints of 0Cr18Ni9/20 clad pipe were prepared by the use of shielded metal arc welding (SMAW) and E309L super-low carbon austenitic stainless steel electrode.Studies on the welded joint were made by means of optical metaloscopy, energy dispersive spectrum, scanning electron microscope, X-ray diffraction and microhardness analy sis. The results indicated that re-heating of cover pass weld can decrease the size and the content of δ-ferrite in transition weld, and the morphology of δ-ferrite in transition weld turns from the vermicular type to the granular type.The chemical compositions of melted zone between transition weld and 0Cr18Ni9 base metal become more uniform.And there was no precipitation of Cr₂₃C₆ carbides in transition weld after re-heating.