| 摘要 |
PURPOSE:To obtain a titled cold-rolled steel plate having marked flangeability and deep drawability by not rolling extra low C aluminum-killed steel above specific temp. and cold rolling the same below the prescribed cold rolling draft and further annealing the cold rolled plate above the recrystallization temp. and below the Ar3 point. CONSTITUTION:The extra low C aluminum-killed steel consisting, by weight %, of <=0.005% C, <=0.5% Mn, 0.005-0.05% Al, <=0.0025% N, <=4C P, <=0.02% (P+5N) and the balance substantially Fe is treated as follows: This steel is melted in an ordinary melting furnace and the molten steel is subjected to ingot making, blooming or continuous casting by a vacuum degassing treatment thereby forming an ingot. After such ingot is hot-rolled at 850-1,200 deg.C finishing temp., the rolled plate is subjected to force cooling at >=30 deg.C/sec cooling rate followed by cold rolling at >=50%, more particularly >=73% cold rolling draft. The cold rolled steel plate is subjected to continuous annealing or box annealing above the recrystallization temp. and below the Ar3 point, whereby the intended cold rolled steel plate is obtained. |
