The effect of low-temperature stress relieving was examined, using a partially penetrated groove weld with a blowhole. Box section specimens measuring 200mm (W)×250mm (H), made of 15mm thick 600MPa class steel were tested. The result proved that stress relief could reliably improve fatigue strength. Compared with the as-welded specimen, the 2000 000-cycle strength of the treated weld increased by about 20MPa.
