Abstract
Ultrasonic impact treatment (UIT), which is a type of peening method, is possible to introduce compressive residual stress deeply among other peening methods. It is considered that UIT is effective for improving fatigue lives of aged welded joints with fatigue cracks. In order to examine the effects of UIT on the fatigue lives of aged welded joints, fatigue tests of aging welded joints treated by UIT were carried out and the results were compared with those of As-weld joints. The fatigue lives of aging web-gusset welded joints treated by UIT increased to more than ten times those of As-weld joints.
