Optical interferometric analysis of fatigue fracture

Electron speckle pattern interferometry (ESPI) is an optical method for non-contact visualization of displacement distribution using a laser. We have previously used this method to analyze the physical mechanism of fatigue fracture from the mesomechanical point of view. Until now, we have used specimens without annealing treatment, but this time we plan to conduct annealing and investigate specimens with different grain sizes compared to those that were not annealed. The purpose of annealing treatment is to remove residual stress inside the material, and residual stress has a significant effect on fatigue fracture. This study aims to compare the differences in fatigue properties between specimens with and without annealing treatment and to clarify the effects of annealing treatment.