Stress evolution in plastically deformed austenitic and ferritic steels determined using angle- and energy-dispersive diffraction

TL;DR

This study investigates stress evolution in textured ferritic and austenitic steels during tensile testing using high-energy X-ray diffraction, revealing the importance of advanced modeling to understand non-linear stress behaviors.

Contribution

It introduces an elastic-plastic self-consistent modeling approach to accurately analyze second-order stress evolution in deformed steels, improving upon previous elastic anisotropy models.

Findings

Eshelby-Kröner model accurately predicts X-ray stress factors.

Non-linearity in stress plots cannot be explained by texture alone.

Plastic deformation of 1-2% can invert second-order stress states.

Abstract

In the presented research, the intergranular elastic interaction and the second-order plastic incompatibility stress in textured ferritic and austenitic steels were investigated by means of diffraction. The lattice strains were measured inside the samples by the multiple reflection method using high energy X-rays diffraction during uniaxial in situ tensile tests. Comparing experiment with various models of intergranular interaction, it was found that the Eshelby-Kr\"oner model correctly approximates the X-ray stress factors (XSFs) for different reflections hkl and scattering vector orientations. The verified XSFs were used to investigate the evolution of the first and second-order stresses in both austenitic and ferritic steels. It was shown that considering only the elastic anisotropy, the non-linearity of $\sin^2{\psi}$ plots cannot be explained by crystallographic texture. Therefore, a more advanced method based on elastic-plastic self-consistent modeling (EPSC) is required for the analysis. Using such methodology the non-linearities of $\cos^2{\phi}$ plots were explained, and the evolutions of the first and second-order stresses were determined. It was found that plastic deformation of about 1- 2% can completely exchange the state of second-order plastic incompatibility stresses.