Application of electro-slag strip overlay welding for clad layer longitudinal weld seam welding of duplex metal metallurgy clad pipes

The welding process of duplex metal metallurgy clad pipes include base metal（ carbon steel） welding and clad layer（ stainless steel or other alloy material） welding. In order to protect the milling groove of stainless steel layer from burning loss by base metal inside submerged arc welding,the proper welding parameters may be matched,but that base metal welding also will generate grooves between edges of base metal inside weld seam and milling groove of clad layer. If the strip overlay welding of clad layer was performed on the inside weld seam of base metal directly,the defects such as incomplete fusion or slag inclusion are easy to be found in the clad layer weld seam. Though comparing different clad layer welding procedures,auto TIG welding + electro-slag strip overlay welding were selected weld both edges of base metal inside welding seam and other clad layer area,respectively. After the inspection and test validation indicate that the clad layer welding procedure not only can effectively reduce defects,but also all the mechanical properties,corrosion-resistance and other requirements of welded joint also can meet standards requirements.