PREVENTION TECHNIQUES OF ROLL SURFACE CRA CK IN TWIN-ROLL CASTER

Thin strip casting of 4.5wt% silicon steel has been carried outwith a twin roll easter with cooling rolls 550 mm in diameter and 500 mm in w idth. The casting speed was of the order of 2.1-5 m/sec and the thickn ess oi the strip varied from 0.2 to 0.5 mm. One of the significant tec hnologies for the casting of tonnage strip is the design of the long-l ived cooling rolls. Micro-cracks occured around the roll surface when casting heats of more than one ton. In these experiments, the roll tem peratures of the inner and outer surfaces were measured during casting and thermal cycle of roll temperature was calculated from the measure d values,Roll deformation behavior and working stress were analyzed by the two dimensional finite element method. Based on these theoretical calculations, this paper reports on (1) surface coating by Ni-Cr plat ing on the rolls, (2) design for an increased cooling water circulatio n rate in the rolls, and (3) application of a Cu alloy sleeve having e xcellent high-temperature strength. By adopting these improvements, th e authors succeeded in producing a thin strip on a 3 ton/heat scale by twin roll casting.