Ni基600合金GTA溶接部におけるX線応力測定の高精度化

概要

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In materials such as Ni-based alloys, the microstructures are formed by mono-phase solidification without solid-state transformation. Measuring the welding residual stress by X-ray diffraction is difficult because of the preferred orientation of the unidirectional solidification and the grain growth in the heat-affected zone. To exclude these effects, a method that records the diffraction peaks in a two-dimensional detector combined with multi-axial rocking is proposed. It is clarified that the equilibrium of shrinkage and the recovery of strain during the thermal cycle determines the site of the maximum tensile stress. In addition, dynamic re-crystallization, which occurs during solidification, contributes to the decreased residual stress at the fusion line. If the spatial resolution of the proposed and the conventional measurement methods can be correlated, the results of each method agree well. Therefore, the proposed method is an effective tool for measuring the residual stress in welded joints of Ni-based alloy.