抄録
The effect of hydrogen on fatigue crack growth behavior of three austenitic stainless steels has been investigated from the viewpoint of martensitic transformation. The crack growth rates in the hydrogen- charged SUS304 and SUS316 were accelerated. The crack growth rate in the hydrogen-charged SUS316L was slightly higher than that in the uncharged SUS316L. The martensitic transformation on fatigue fracture surface was detected by the X-ray diffraction method in both the hydrogen-charged and uncharged specimens of SUS304, SUS316 and even SUS316L. However, SUS316L showed less martensitic transformation than SUS304 and SUS316. It is presumed that the martensitic transformation in the vicinity of fatigue crack tip contributed to the effect of hydrogen on crack growth rate. The fracture surface was examined by SEM in SUS304 and SUS316L. Clear striations were observed on the fatigue fracture surfaces of the uncharged specimens of SUS304 and SUS316L. Striations were also observed in the hydrogen-charged SUS304 and SUS316L. However, especially in the hydrogen-charged SUS304, striations were less distinct than those in the uncharged SUS304.
