| 摘要 |
PURPOSE:To manufacture cold-rolled high tensile steel plate having excellent strength-ductility balance by the procedure in which a steel piece having a specific composition and a two-phase ferrite and martensite structure is cold-rolled and then subjected to a specific heat treatment before annealing. CONSTITUTION:A steel piece, containing 0.05-0.20% C, 0.20-1.50% Ci, 0.30- 2.5% Mn, 0.05-0.20% soluble Al, <0.02% N, and one or two or more of 0.05- 0.15% V, 0.20-0.50% Mo, and 0.20-1.00% Cr, and also having a structure consisting of the two phase, ferrite and martensite, is hot-rolled, cold-rolled, and then subjected to a mormalizing treatment at a temperature between the transformation point A3 and 1000 deg.C for 1-600sec before annealing. Thus, a fiber structure developed during the cold rolling process is eliminated and cold-rolled high tensile steel plate having excellent high strength-ductility balance can be obtained. |
