| 摘要 |
<p>PURPOSE:To continuously manufacture a thick steel plate excellent in internal quality from a slab by completely press-welding porosities even in rolling at low rolling reduction ratio of the specified rolling reduction ratio of 1.5-2.0. CONSTITUTION:When the front and back surfaces of the slab is water cooled during rolling after uniformly hating the slab 1 which is manufactured by continuous casting method at a temp. of >=1250 deg.C and the slab is rolled by making a temp. difference between those front and back surfaces and the center part of thickness, cooling is controlled so that the front and back surfaces in the range of the middle part 3/4 to the entire width of the slab have a temp. difference of >=200 deg.C between the center part in the thickness direction. After that, by executing rolling of >=2 passes that rolling shape ratio of >=0.40/pass is ensured on the basis of the max. rolling reduction that is bearable to the capacity of the rolling mill, a extremely thick steel plate with press-welded porosities that are generated in the vicinity of the center of the thickness of slab is manufactured.</p> |
