Creep-rupture behavior and creep strain distribution of welded joints of 304 stainless steel thick plates
Hongo Hiromichi; Yamazaki Masayoshi; Watanabe Takashi; Kinugawa Junichi; Monma Yoshio
Abstract:Using hot-rolled 304 stainless plate (60mm thick) and 308 filler wire, a narrow-gap butt welded joint was prepared by GTAW (gas tungsten arc welding) process. In addition to the conventional round-bar specimens of the base metal and weld metal, the full-thickness joint specimens were prepared and subjected to creep tests at 550 degree, from 196 to 294MPa. The creep strain distribution on the surface of each large joint specimen was measured by moire interferometry. The hardness of the weld metal at the surface is less than that of the inside which is significantly affected by thermal cycling during welding. This means that the heart of the weld metal is overmatched, but the layers near the front and back surfaces are undermatched. The creep-rupture strength of the large joint is about 85% of that of the overmatched weld metal. The initiation of cracks occurs in the beads at closet to the front and back sides. On the basis of the above observations, it is recommended to have the data of large joint specimens in order to interpret the creep life of the multi-pass welded joints. Key Words:304 atainless steel, welded joint, creep strain distribution, creep rupture behavior, fracture location