Quantification of compositional and residual stress effects on lattice strain in dual-phase stainless steels by means of differential aperture X-ray micro-diffraction

Residual stress is an important factor for evaluating the deformation and failure of engineering materials. Diffraction-based measurement assumes that the full measured lattice strain tensor contributes to residual stress according to Hooke's Law. The present work focuses on the lattice strain determination of individual grains in a dual-phase stainless steel (DPSS) by means of differential-aperture X-ray micro-diffraction (DAXM). The results show that the residual stress only takes part of the responsibility of the total measured lattice strain. In fact, the compositional variation inside the material was found to cause greater strain gradient in both ferrite (α) and austenite (γ) phases in DPSS. Therefore, quantification of compositional and residual stress effects on lattice strain was conducted in order to evaluate the true residual stress inside engineering materials.