In order to guarantee welding quality and prevent welding defects, welding procedure and welding defects of SUPER304H were studied. Welding procedure was judged by qualification tests in accordance with Welding Procedure Qualification Regulation. Welding defects were discussed using observations of the metallurgical structure as well as photographs. The results show that normal procedure is very important for gaining excellent welding quality. Weld defects such as lack of penetration, lack of fusion, overlap, penetration, gas pores and overheat easily appear when welding under abnormal weld procedures, which include insufficient or excessive weld input, much higher weld interlayer temperature, and no inert gas protection in the interior. The authors therefore suggest carrying out normal welding technology strictly during welding operation to avoid weld defects effectively and to obtain high quality weld joins.
