PRODUCTION OF OXIDE GRAIN DISPERSED CAST BLOOM FOR REFRACTORY USE AND ROLLED SHAPE STEEL FOR REFRACTORY USE, USING THIS CAST BLOOM AS STOCK

摘要

PURPOSE: To attain superior refractoriness and toughness by subjecting a cast bloom, in which Al-Mg-Ti compound oxides are dispersed, to heating/cooling type controlled rolling. ;CONSTITUTION: A molten steel, having a composition containing, by weight ratio, 0.04-0.20% C, 0.05-0.50% Si, 0.4-1.8% Mn, 0.4-1.0% Mo, 0.05-0.20% V, 0.004-0.015% N, and 0.005-0.025% Ti, is preliminarily deoxidized, by which the amount of dissolved oxygen is regulated to 0.003-O.015%. Then, an Fe-Al-Mg alloy is added and the amounts of Al and Mg are regulated to 0.005-0.015% and 0.001-0.010%, respectively. The molten steel is cast and cooled down to 900°C at a rate of (0.5 to 20)°C/s, by which Al-Mg-Ti oxides of a size of ≤3μm are incorporated into the resulating cast bloom by ≥20pieces/mm². Subsequently, the cast bloom is heated to 1100-1200'C and rolling is started, and then, water cooling is done until a bloom surface layer temp. of ≤700°C is reached and rolling is performed in the course of recuperation between passes. This process is repeated once or more. After the completion of rolling, cooling is done down to 650-400°C at a rate of (1 to 20)°C/s, followed by air cooling.;COPYRIGHT: (C)1995,JPO