カソード分極に伴うSUS304ステンレス鋼への水素侵入と水素脆化

概要

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In this work, the mechanism of the hydrogen penetration into SUS304 stainless steel and the effect of dissolved hydrogen on the mechanical properties were investigated. The SUS304 stainless steel specimens were annealed at 1273K and cathodically polarized in an H_2SO_4 solution. Hydrogen analysis was done immediately after interruption of cathodic current. When the specimens were cathodically polarized, hydrogen atoms penetrated into the specimens. The hydrogen penetration was clarified to be rate-determined by hydrogen diffusion. So, from the polarization time dependence of the concentration of hydrogen, the diffusion coefficient of hydrogen D_H was determined to be 1×10^<-13>m^2/s at 298K. This value of D_H is 2 orders of magnitude larger in than that extrapolated from the values of D_H at high temperatures reported so far. The dissolved hydrogen caused a significant decrease of elongation in a stress-strain curve. On fractured surface of the hydrogen charged specimens, the regions of brittle fracture and ductile fracture were observed. The brittle region was near the specimen surface, and the depth of brittle region almost agreed with penetration depth of hydrogen calculated by using the value of D_H obtained in this work.
福井工業大学の論文