| 摘要 |
PURPOSE:To improve press formability and paintability at <=60% yield ratios by cold-rolling a steel contg. specific amts. of C, Mn, and Al and subjecting the same to box annealing for the residence time determined by the specific equations in a temp. region above the Ac1 point then to heating to an alpha-gamma region followed by continuous annealing at specific cooling rates. CONSTITUTION:The steel consisting of 0.02-0.12 C, 0.5-0.8 Mn, <0.1 Al, by weight % and the balance Fe is cold-rolled, and the cold-rolled plate is subjected to box annealing for >= time (t) wherein the residence time is determined by the equations within an AC1-AC1+100 deg.C range. Therefore, it is subjected to heating for >=1sec in an alpha-gamma region then to continuous annealing wherein average cooling rates from the heating temps. down to below 300 deg.C are kept at <=200 deg.C/s at >=CR ( deg.C/s) of the equations. |
