Abstract
The effects of laser peening (LP) on the bending fatigue limit of an austenitic stainless steel JIS-SUS316 welded joint containing an artificial semi-circular slit on the weld toe were investigated. The optimum LP condition which was expected to have a good effect in fatigue limit improvement was determined by measuring the residual stress distributions for several LP conditions. Then, three-point bending fatigue tests were carried out at a stress ratio of R=0.05 for both LP treated welded specimens with the slit on the weld toe and those without the slit. The fatigue limits of all specimens increased by 23-64% due to LP. LP treated specimens with a slit depth of a=0.2 mm had high fatigue limits that were nearly equal to those of non-slit, LP treated specimens. Therefore, a semi-circular slit of less than a=0. 2 mm could be rendered harmless due to LP. The improvement of fatigue limit due to LP was mainly achieved by compressive residual stress.
