Abstract: Variation and distribution of welding residual equivalent stress, circumferential stress and axial stress in 16MND5 steel thick-walled cylinders under different heating conditions of local heat treatment standards (B31.1, B31.3, ASME section NB, BS2633 and AWS D10.10) were studied by using the viscoelastic plastic finite element method. A comprehensive analysis was conducted on the welding residual stress in the center and vicinity of the weld seam, as well as on the heat treatment stress attached to the edge of the heating zone. The influence of heated band width and insulation band width on the local post weld heat treatment effect was also discussed. The results show that after local heat treatment, uneven heating at the edge of the heating zone causes a certain increase in stress, and the presence of the insulation zone can alleviate the temperature gradient, thereby reducing the additional stress at the edge of the heating zone. For thick-walled cylinders, when subjected to local heat treatment according to AWS D10.10 standard, the center of the weld seam can achieve a similar effect as the overall heat treatment, and the residual stress relief effect of welding is the best.

Key words: thick-walled pipe, 16MND5 steel, local post weld heat treatment, heated band width, insulation band width