| 摘要 |
PROBLEM TO BE SOLVED: To provide Ni refined steel excellent in tempering brittleness resistance and hydrogen brittleness resistance. SOLUTION: In steel contg., as fundamental components, by weight, 0.05 to 0.4% C, 0.02 to 0.6% Si, 0.02 to 2.0% Mn, 0.02 to 3.0% Mo, 0.01 to 5.0% Cr, 3.0 to 10.0% Ni, 0.001 to 0.03% P, 0.0005 to 0.03% S and 0.001 to 0.015% N, and the balance Fe with inevitable impurities, the content of Al in the old austenitic grain boundaries is controlled to >=0.6%, or the content of Al-(Si+Mn+Cr)} in the grain boundaries is controlled to the value of >=3%, or the content of (Si+Mn+Cr) in the grain boundaries is controlled to <=3.5%. If required, one or >= two kinds among Cu, Nb, V, Ti and B are moreover incorporated therein.
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