Analysis on Causes for Solidification Cracking of High Strength/ Small DS Ratio SAWH Pipe and Relevant Control Measures

Addressing the problem concerning the solidification cracks occurring with the X70 Ф813 mm×17.5 mm SAWH pipes during the manufacturing process,the causes are analyzed based on the formation mechanism of such defect, and the characteristics of manufacturing process of the pipe. Accordingly, countermeasures are determined and taken,including reducing formation stress,properly controlling formation consistency,optimizing weld pattern,and cutting down heat input for welding,etc. As a result,the occurrence frequency of the cracking is remarkably reduced. This experience is helpful for production of high strength/small DS ratio SAWH pipes.