1985 年 3 巻 3 号 p. 490-497
In this work, the trapping effect of inclusions on hydrogen diffusion was investigated and it was considered how this trapping effect affected on hydrogen embrittlement.
The results in this work were as follows;
(1) At room temperature diffusion coefficients were lowered and nondiffusible hydrogen contents were increased with increasing inclusions. Therefore, it was aquired that inclusions acted as both reversible and irreversible trapping sites in steels.
(2) It was appeared that nondiffusible hydrogen was trapped in inclusions and microvoids produced at inclusions at room temperature.
(3) It was appeared by measurement of binding energy between trapping sites and hydrogen that reversible trapping effect of inclusions on hydrogen diffusion was caused by dislocation fields developed around inclusions during oil quenching of steels.
(4) It was concluded by considering the model of hydrogen embrittlement proposed by Beachem that the index of hydrogen embrittlement was relative to concentration of hydrogen at the crack tip. And it was appeaered that inclusions lowered the concentration of hydrogen, thus elevated KTH.
(5) KTH values were elevated by Ce treatment, while diffusivity of hydrogen was not affected by Ce treatment. The reason of this result was caused by the upward shift of critical line in Beachem model because of higher KIC of Ce treated steel.