白點状缺陷に關する研究(III)

Abstract

The effect of hydrogen on the flakeformation was summerized follows:(1) The degree of flakeformation was generally parallel to the total hydrogen of steel, that is, if the total hydrogen content increase, flakes appeared more violently and if the content decrease, the appearance of flakes weakened and then vanished. As the more quantitative representation, if the total hydrogen content be more than 6×10-4% H2, flakes appeared surely, but less than 4×10-4% H2, flakes vanished. Then it was confirmed that steel has a critical total hydrogen content to the flakeformation, but this critical value has a wide range of about 2×10-4% H2.(2) The degree of flakeformation telated more closely to the hydrogen content evolved from the steel in the room temperature than the total hydrogen content did not relate at all to the hydrogen content evolved only in the high temperature. That is, if the hydrogen content evolved in the room temperature be less than the critical value, flakes would not appear even if this steel has a high total hydrogen content, but if more than critical value, flakes would appear even if the steel has a less total content than the former. In this experiments the critical value was about 2cc H2/100g Fe, but also had a narrow breadth.(3) From the results of this and the former (2nd Report) expriments, it was confirmed that the supersaturated hydrogen in steel would be playing a substantial role in the frakeformation.