Chengshuang Zhou

Effects of External Hydrogen on Hydrogen Transportation and Distribution Around the Fatigue Crack Tip in Type 304 Stainless Steel

The effects of external hydrogen on hydrogen transportation and distribution around the fatigue crack tip in type 304 stainless steel were investigated by using hydrogen microprint technique (HMT) and thermal desorption spectrometry. HMT results show that some silver particles induced by hydrogen release are located near the fatigue crack and more silver particles are concentrated around the crack tip, which indicates that hydrogen accumulates in the vicinity of the crack tip during the crack growth in hydrogen gas environment. Along with the crack propagation, strain-induced α′ martensite forms around the crack tip and promotes hydrogen invasion into the matrix, which will cause the crack initiation and propagation at the austenite/α′ martensite interface. In addition, the hydrogen content in the vicinity of the crack tip is higher than that at the crack edge far away from the crack tip, which is related to the stress state and strain-induced α′ martensite.