Mechanical Behavior in Local Post Weld Heat Treatment (Report IV) : Influence of residual stress distribution in multi-pass welding(Mechanics, Strength & Structure Design)

概要

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Local post weld heat treatment (local PWHT) is usually performed for tempering and relaxation of residual stresses. The degree of stress reduction is influenced by the initial welding residual stress and the local PWHT applied. The residual stress distribution after the local PWHT for multi-pass welding joint of a pipe with heavy wall thickness is not very clearly understood yet. In this paper, the time history and the final distribution of the stress components under local PWHT, with different types of multi-pass welding process, have been studied. The local PWHT on the butt joint of a pipe is analyzed using an axisymmetric FEM model. Results show that the welding residual stresses change with the sequence and number of welding passes. The residual stress on the outer surface decreases slowly with the increase of the heated band width. On the contrary, the residual stress on the inner surface can be removed effectively with relatively small heated band width. Excessively wide heated band widths appear ineffective to further reduce the residual stress.
大阪大学の論文