Analysis by speckle interferometry of the dependency of yield stress on residual stress

We used electronic speckle pattern interferometry (ESPI) to measure in situ displacement fields nondestructively and with high resolution (10⁻² μm) by using the interferometry principle and the phase-shift technique. We measured the depth profile of the residual stress in steel pipe manufactured by thermomechanically controlled processing using a quantitative model, which explains the relationship between residual stress and displacement measured by ESPI in chemical etching. We analyzed the variation of yield stresses measured by the indentation technique and the residual stresses at various depths. The relationship between the residual stresses and the yield stresses was consistent with simulated results and can be used for indirect evaluation of the residual stresses from the yield stresses.