Strain Measurement of Aged Duplex Stainless Steel Using SR White X-Rays

Abstract

Duplex stainless steels (DSSs) have microstructures of α and γ-phases of iron and exhibit changing of their mechanical properties by aging above 300°C, so that strain behavior is expected to be complicated under stress loading. In order to estimate lattice strains and to determine their behavior, lattice strain measurements of aged DSSs have been performed using synchrotron radiation white X-rays. As a result, it was found that the lattice strain was not always correspond with applied macro strain, and the lattice strains of γ-phase showed no elongation in comparison with those of α-phase in the aged specimen. These results mean that complex strain distributions between (hkl) planes already exist in the early stage of elastic deformation, and suggest that fracturing of aged DSSs under tensile loading occurs preferentially on γ-phase rather than α-phase.