Application of strain tomography and contour method to residual stress analysis in additively manufactured CM247LC superalloy parts.

Abstract

Residual stresses are recognized as a critical factor influencing the mechanical performance and structural integrity of additively manufactured parts, particularly in nickel-based superalloys. Although the contour method and strain tomography have been applied independently for residual stress evaluation of such materials, a direct comparison of their reconstructions in laser powder bed fusion fabricated specimens has not been reported. In this study, both techniques were employed on identically produced specimens of CM247LC superalloy, and a strong qualitative agreement in residual elastic strain distributions was observed. Using the contour method, tensile residual stresses up to +1300 MPa were identified near the specimen edges, while compressive stresses approaching - 600 MPa were found in the central regions. Strain tomography, based on synchrotron X-ray diffraction, was used to non-destructively reconstruct internal residual elastic strain fields, revealing consistent trends and capturing localized variations aligned with the contour method. Through this integrated approach, a complete validation of stress reconstruction was achieved, and new insights into the stress evolution of laser powder bed fusion manufactured CM247LC were provided. The findings demonstrate how the complementary strengths of these techniques can be leveraged for improved residual stress characterization in high-performance superalloy parts.