ROLLING METHOD OF THICK PLATE

摘要

PURPOSE:To decrease the internal defect in an edge part by giving a difference in wall thickness to a rolled material at the section in a rolling direction thereby subjecting the edge part to rolling under stronger rolling reduction under the same rolling load as in the prior art. CONSTITUTION:A heated slab 1 is rolled at a changed rolling reduction in the final pass in a rolling stage for forming into a rolled material 2 having the shape wherein the preceding and succeeding end parts at the section in the rolling direction are thicker than the central part. Such a material is then turned 90 deg. and the thick walled part is subjected to rolling under strong rolling reduction by cross rolling (3-5 passes) in parallel with the pass direction whereby a rolled material 3 having a uniform thickness is obtd. The rolling reduction necessary for eliminating the internal defect in the thick wall part is thus obtd. The material 3 is in succession rolled at the changed rolling reduction in the final pass of the same rolling into a rolled material 4 having the shape wherein the preceding and succeeding ends at the section in the rolling direction are thicker than the central part. Such a material is turned 90 deg. and the thick walled part is rolled under the strong rolling reduction by the finish rolling wherein the thick wall part is made parallel with the pass direction into a rolled material 5 having a uniform thickness. An intended rolled material 6 is obtd. upon completion of the finish pass.