冷間圧延した安定および準安定オーステナイト系ステンレス鋼の水素ぜい化特性の比較

抄録

Hydrogen embrittlement has been investigated on metastable and stable austenitic stainless steels cold-rolled by 0% to about 60%. The specimens were made of Fe-18% Cr-8% Ni (18-8), Fe-25% Cr-19% Ni (25-19) and Fe-24% Cr-13% Ni with 0.3% N (24-13/N); N was added to save the Ni content. The bend test was used to evaluate the hydrogen embrittlement, and the number of bending before failure was measured for H-free and H-charged specimens (N: H-free, N_H: H-charged). The main results are as follows:
(1) The number of bending before failure decreased with increasing H-charging. For specimens with the same Vickers hardness, N_H was in the order of 24-13/N>18-8>25-19.
(2) The ratio of hydrogen embrittlement [R_H=(N-N_H)/N] was in the order of 18-8>24-13/N>25-19. For 18-8, R_H increased with increasing Vickers hardness. For 25-19 and 24-13/N, however, R_H decreased with increasing Vickers hardness and R_H for 25-19 was smaller than that for 24-13/N.
(3) The thickness of the hydrogen embrittlement layer in 18-8 increased with increasing cold-reduction but those of 25-19 and 24-13N did not change.
(4) H-charging produced surface cracks on solution-treated specimens and less cracks on cold-rolled specimens: blisters were most noticeable on cold-rolled 18-8. The surface change due to H-charging was more marked on 25-19 than on 24-13/N.
(5) For 25-19 and 24-13/N, hydrogen-induced ε-martensite content decreased with increasing cold-reduction. The ε-martensite content of 25-19 was larger than that of 24-13/N.