1988 年 37 巻 413 号 p. 223-228
In the previous paper, the holding time was found to be an influencing factor for the hydrogen embrittlement of stainless in 3% NaCl solution. In this study, in order to elucidate the relation between the cathodic potential and mechanical properties, the slow strain rate tension tests were carried out under the environment of hydrogen evolution successively after the specimens were held for various time periods in hydrogen evolution potential.
The main results obtained are summarized as follows.
(1) The embrittlement ratio obtained from the reduction of area decreased continuously with increasing holding time in each setting potential. This tendency became more pronounced at lower setting potential. Consequently, although the contraction of specimen decreased only slightly in every direction, a remarkable embrittlement phenomenon could be found. The same results were also obtained for the time to fracture.
(2) The degradation of mechanical properties accompanied with the hydrogen embrittlement was also noticed in the rupture behavior or the observation of fracture surface by S.E.M.. In particular, the results observed by S.E.M. indicated that the transgranular fracture including quasi-cleavage fracture increased in the outside region of specimen and the dimple caused by ductile fracture decreased in the inside region of specimen.