Residual Stress of X80 Large-Diameter SAWH Pipe

Residual stress of X80 large-diameter SAWH pipe with different forming parameters were examined by blind hole drilling method and slit-ring method, then the residual stress level and distribution and cause were analyzed. The results show that the residual stress of X80 large-diameter SAWH pipe was complicated and the distribution and level of residual stress reflected the forming parameters during forming of X80 SAWH pipe. The peak residual stress appeared at the inner surface of weld seam zone of the X80 large-diameter SAWH pipe. The over lapping deformation in the slit-ring test was due to extra press value, which resulted in the residual tensile stress on inner surface was larger than that on outside surface.