Residual stress improvement by means of induction heating

The intergranular stress corrosion cracking (IGSCC) of austenitic stainless steel is considered to occur when the three factors, material sensitization, tensile stress and environment condition, exceeds some threshold simultaneously. As to the tensile stresses, it is considered that the weld residual stress is one of the most important factors. The newly developed technique, Induction Heating Stress Improvement (IHSI) is intended to lower the tensile weld residual stress in the inner surface of the pipe. Many basic experiments and full-sized mock-up test on the actual austenitic stainless steel pipes; 4 in., 10 in., and 12 in., and calculations using finite element technique were conducted in order to find out appropriate heating conditions and verify the effectiveness of IHSI. As the results, the key parameters which have significant effects on IHSI results were determined