Influence of SAWL Process on Yield Strength of X65M Steel

Analyzed in the paper，taking a certain type of X65M steel plate as an example，is the influence of the SAWL process on the final yield strength of the weld tube.The analysis leads to the following conclusion.The formation process has strong influence on the yield strength of the X65M steel plate，so the yield strength of the base metal after formation will decrease by 30～70 MPa.And although the expanding process may increase the yield strength，the increasement is not good enough to make up for the loss of yield strength resulting from formation. Moreover，the yield strengths of the rod specimens are generally higher than the plate specimens，but the differences are not big.It is suggested that the tube manufacturers carry out sufficient evaluations on the physicochemical property and metallographic structure of the raw material and predict the changing trend of the yield strength，so as to prevent the yield strength of the final tube from going beyond the requirements of applicable standard.