MANUFACTURE OF TUBULAR WELDED MOLD MATERIAL FOR STEEL ELECTROMAGNETIC STIRRING CONTINUOUS CASTING EXCELLENT IN TOUGHNESS AT HIGH TEMPERATURE

摘要

PURPOSE:To manufacture the titled tubular welded mold material excellent in toughness at high temp. by forming a square tube stock of a copper alloy ingot with a specific composition and successively applying annealing, quenching, cold reduction, and aging treatment to the above under respectively specified conditions. CONSTITUTION:An ingot of a copper alloy consisting of, by weight, 2.0-4.0% Ni, 0.4-1.0% Si, 0.05-1.0% Zn, 0.02-0.1% Mn, 0.001-0.01% Mg, further 0.001-0.1%, in total, of one or more elements selected from Cr, Zr, and Ti, and the balance Cu with inevitable impurities is hot-rolled and worked, and the resulting metal plate is bent into a U-shape and subjected to butt welding so as to be formed into a square tube stock. This tube stock is annealed at 750-800 deg.C for 30min-1hr and then quenched in water from =650 deg.C. Subsequently, the above tube stock is subjected to cold reduction at a draft of 10-15% reduction in area and then to aging at 490-550 deg.C for 2-4hr. By this method, the tubular welded mold material excellent in strength at high temp., yield strength, heat resistance, etc., can be obtained and, as a result, the service life of the mold can be remarkably improved.