| 摘要 |
PURPOSE:To obtain nonaging hot rolled steel plate having high ductility, gammavalue and good workability, by adopting a large draft to steel having a specified compsn. at a specified temp. range in r' region, regulating finish rolling condition and coiling it at a specified temp. CONSTITUTION:Steel composed of, by weight <=0.015% C, 1.0-2.5% Mn, 0.005-0.10% Al, 0.01-0.06% Nb, 0.01-0.1% Ti and the balance Fe with inevitable impurity is rolled as hot slab state or after being heated to >=1,150 deg.C by heating furnace. In the rough rolling, one pass by a large draft of >=20% per one pass is applied by one time or more at 980-1,100 deg.C range, finish rolling is completed at Ar3-930 deg.C. Total draft at Ar3+<=150 deg.C therein is regulated to >=90% and the plate is coiled at 600-800 deg.C. Steel obtd. in such a way has high r value in 45 degree direction and is suitable to working such as square cylinder drawing.
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