Metallographic structure was observed using a replica method. Carbide or tempering bainite was observed in a deposited metal and a heat affected zone of post weld heat-treated mocked-up test pipe.

Hardness was measured by a velocity ratio test, which measures the ratio of the rebound velocity to the impact velocity of the impact body. Hardness of a heat-affected zone was higher than 250 Hv before the post weld heat treatment in mocked-up test pipe, and it decreased below 250 Hv after the post weld heat treatment.

Three methods of residual stress measurements, X-ray diffraction method, hole drilling method and magnetic anisotropy method, were applied to mocked-up test pipes.

Only hole drilling method was unsuccessful because it was very difficult to drill the shallow hole on the pipe surface with accuracy. The X-ray diffraction method was considered difficult to be applied to the welded pipe joints in the actual power plant piping assessment because of its system complexity. As a result of mocked-up tests by the magnetic anisotropy method, it was found that measured residual stress distributions and values were characteristically different between non-stress relieved and stress relieved mocked-up test pipes with actually enough dimensions to evaluate the residual stress. Accordingly the magnetic anisotropy method using simple and lightweight equipment was employed for the measurement of the residual stress in the actual pipe joints. Master curve of the output of magnetic anisotropy sensor vs. the applied stress was obtained by uni-axial tensile test. Using the obtained master curve, the residual stresses in mocked-up welded pipe joints with and without the post weld heat treatment were measured. The residual stresses in the joints with the post weld heat treatment were much lower than those in joints without the post weld heat treatment.