Research on Welding Process of X65 SAWL Pipe with Thin Wall

Two different kinds of welding process parameters,that is inside and outside double wires welding and three wires welding,were tested on X65 grade JCOE pipe with 9.5 mm wall thickness,and the welding joints properties of both welding processes were analyzed.The results showed that both welding schemes can meet the technical requirements,however,all indexes of pipes manufactured by double wires welding process are better.Adopting double wires welding process to carry out mass production,the tensile property of weld can meet standard requirements,and all fracture locations are on the base metal.The hardness of base metal,weld and heat affected zone are all lower than the maximum allowable hardness 265HV10 specified in technical requirement.The weld structure is acicular ferrite,so that the welding joints possess good toughness property.