| 摘要 |
<p>Provided are a steel product having a Ni content less than the 9% Ni steel and exhibiting equivalent properties to those of the 9% Ni steel; and a method for producing the said steel product. The above steel product is a steel product usable at a low temperature, characterized in that it has a chemical composition, by mass percent, of C: 0.01 to 0.1%, Si: 0.005 to 0.6%, Mn: 0.3 to 2%, Ni: more than 6% to less than 8%, sol.Al: 0.005 to 0.05%, N: 0.0005 to 0.005% and the balance: Fe and impurities, with the proviso that the following formula (1): 20C + 2.4Mn + Ni ‰¥ 10 ····· (1), is satisfied; it contains austenite of 1.7% or more in area ratio or it further contains cementite. The said austenite has an aspect ratio of 3.5 or less in average and an average circle-equivalent grain diameter of 1.0 µm or less and /or the said cementite has an aspect ratio of 5.0 or less in average and an average circle-equivalent diameter of 0.6 µm or less. The steel product may further contain one or more selected from among Mo, Cu, Cr, V, Nb, Ti, B, Ca and Mg.</p> |
