| 摘要 |
PURPOSE:To produce economically a titled Ni steel having excellent strength, ductility and toughness, and a characteristic for stopping the propagation of a brittle breaking by hot rolling a specifically composed low carbon steel contg. Si, Mn, Ni, S, Al, and N at a high comulative draft, and cooling quickly the steel at around the transformation point then allowing the steel to cool. CONSTITUTION:A steel contg., by weight %, 0.015%<C<=0.15%, 0.05-0.9% Si, 0.3-2.0% Mn, 0.5-6.0% Ni, <=0.010% S, 0.01-0.1% sol.Al, and <=0.008% N and the balance consisting substantially Fe is treated as follows: Said steel is hot rolled at a cumulative draft of >=30% in the un-recrystallization region of austenite and is then cooled at a cooling rate of 5-30 deg.C/sec in a range down to 500-650 deg.C and in succession, the steel is allowed to cool. The un-tempered low temp. Ni steel having >=33kg/mm.<2> yield strength and >=45kg/mm.<2> tensile strength is thus produced. A part of said Fe may be replaced with >=1 kind among 0.1- 1.0% Cr, 0.05-0.5% Mo, 0.005-0.1% V, 0.005-0.03% Ti, etc. according to need. |
