Method of manufacturing steel for low temperature services
AssigneeNippon Kokan Kabushiki Kaisha
InventorsHiroyoshi Matsubara, Tatsumi Osuka, Tadao Sugiyama
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Abstract
A low alloy steel substantially consisting of Ni-Cr-Cu-Nb system and further adding 0.01 to 0.10% rare earth metals or their alloy thereto, and then being as only hot-rolled by 30 to 80% rolling rate at a temperature of less than 950.degree.C. The steel exhibits absorption energy of at least 10kg-m at -20.degree.C and a .sub.D T.sub.C transition temperature of lower than -40.degree.C, if necessary, may be tempered at a temperature of 500.degree. to 680.degree.C to improve the properties.
Claims2
A method of manufacturing steel for low temperature services consisting of the following chemical composition,
- 0.02 to 0.10% C, 0.10 to 0.50% Si, 1.20 to 1.80% Mn, up to 0.030% P, up to 0.015% S, 0.05 to 0.50% Ni, 0.05 to 0.50% Cr, 0.05 to 0.50% Cu, 0.01 to 0.10% Nb, unavoidable impurities and the balance being Fe,
- further adding rare earth metal or an alloy thereof of 0.01 to 0.20% to the above steel at the stage of vacuum degassing or of pouring into a mold, and then, being as only hot-rolled at a rolling rate of from 30 to 80% at a temperature below 950.degree.C.
Dependencies are inferred from the claim text.