高圧水素ガス中におけるオーステナイト系ステンレス鋼溶接金属の疲労寿命特性

抄録

In order to clarify the effect of hydrogen on the fatigue life properties of austenitic stainless steel welds, 317L and 308, fatigue life tests were performed in 115 MPa-hydrogen gas at room temperature. The specimens for fatigue life test were extracted from a weldment by tungsten inert gas (TIG) welding. The base metals of multi-pass weldment were SUS316 (hi-Ni) bar for 317L steel weld, and SUS304 plate for 308 steel weld. Two series of weld metals were tested; one was as-welded (AW) metal having coarse columnar grain with dendrite and δ-ferrite, and the other was post-welded solution-treated (PWST) metal having coarse equiaxed grain without dendrite and δ-ferrite. In high-pressure hydrogen gas, the fatigue limits both as 317L and 308 welds were not decreased, as compared with that obtained in air. In modified S-N curves that considers the deference of tensile strength between AW and PWST metals, the fatigue life properties of 317L steel weld showed good agreement in that of base metals, whereas there was a large discrepancy between the fatigue life properties of 308 steel weld and base metal. The fatigue life property of AW metal was higher than that of PWST metal both in 317L and 308 steel welds.