Identification of mechanical behavior of materials with graded properties using HEXRD and numerical simulations

: The mechanical behavior of carburized Ti-stabilized austenitic stainless steel was investigated by combining in situ tensile tests, high-energy X-ray diffraction (HEXRD), and finite element modeling. Carburizing at 500 °C for 1000 h and 3000 h generated strong through-thickness gradients in carbon content, microhardness, and residual stresses, leading to marked local variations in mechanical response. HEXRD measurements showed that carbon enrichment increases local yield strength and early strain hardening, but also revealed substantial differences in apparent behavior that could not be explained by carbon content alone. A modeling framework was therefore developed to separate the respective contributions of carbon and residual stresses. This approach successfully identified the intrinsic constitutive parameters for the 1000 h condition and reconstructed the residual stress profiles for the 3000 h condition with results consistent with experimental observations. Residual stresses were found to strongly alter the apparent tensile response, and neglecting them can overestimate yield strength by up to 30%. These results demonstrate the need for local mechanical characterization and stress-aware modeling to describe carburized materials with graded properties.