Heterogeneity of Creep Properties of Welds on 304 Stainless Steel Plate
Yamazaki Masayoshi; Hongo Hiromichi; Watanabe Takashi; Kinugawa Junichi; Tanabe Tatsuhiko; Monma Yoshio
Abstract:An welded joint of 304 stainless steel was fabricated by SAW with use of 308 filler metal to investigate the influence of welding pass sequence and sampling location of the specimen in the welded joint on the creep properties of weld metal zone and heat affected zone in the joint. Creep tests were conducted at 823K and 235MPa. In the HAZ of the welded joint, there existed a hardened region of which specimen showed a little smaller creep rate and longer life than base metal. The 308 weld metal had larger creep rate than the 304 base metal and the life of the former was only 10% of that of the latter (under matching), however, the difference of the lives becomes smaller for long times. 0.2% proof stress and creep properties of the weld metal zone depended on the sampling location in the welded joint due to the effect of the weld pass sequence and the restraint used during welding. The most important factor that affects the creep properties of weld metal zone would be the difference of micro structure among the beads which was generated from the pass sequence on multi layer welding. From the results mentioned above, it is necessary, on evaluating the strength of the joint and predicting its life simulation, to take the heterogeneity of the mechanical properties within the welded joint into account. Key Words:creep property,304 stainless steel, 308 weld metal, welded joint, welding performance, heterogeneity