Evaluation of subsurface distribution of residual stress in austenitic stainless steel using strain scanning method

Shobu, Takahisa  ; Konishi, Hiroyuki; Mizuki, Junichiro; Suzuki, Kenji*; Suzuki, Hiroshi  ; Akiniwa, Yoshiaki*; Tanaka, Keisuke*

The strain scanning method was applied to the evaluation of the subsurface distribution of the residual stress beneath the shot-peened surface of an austenitic stainless steel SUS304L which had coarse grains and preferred orientation. The experiment was performed at beam line BL22XU at SPring-8 using monochromatic X-rays of 70.14 keV and a Ge (111) analyzer. The specimens were annealed or shot-peened and the grain size was about 0.037mm. In order to obtain the diffractions from an enough number of grains, various types of oscillation methods, which were translation, rotation and tilting of the specimen, were examined. The translational oscillation was found to be enough to obtain the accurate strain distribution. By combining the translational oscillation method with the correction to the surface aberration, the subsurface distribution of the residual stress of shot-peened austenitic stainless steel was successfully determined.