METHOD OF PRODUCTION AND TREATMENT OF ALLOYED CASTING MATERIAL, CASTING MATERIAL FOR WORKING PART OF ROLLS AND COMBINED ROLL Russian patent published in 2004 - IPC

FIELD: metallurgy; methods of production of alloyed material for combined rolls of wide- strip and thick-strip rolling mills. SUBSTANCE: proposed method includes preparation of melt of the following chemical composition, mass-%: carbon, 2.0-35; silicon, 1.0-2.0; manganese, 0.5-2.0; chromium, 1.0-3.0; nickel,,3.5-4.9; molybdenum, 0.2-2.9, the remainder being iron and admixtures. Vanadium is added in the amount of up to 5.9 mass-% and is dissolved; composition of melt is regulated by means of alloying due to setting concentration of carbon and silicon in presence of nickel; sum of activities of carbide-forming elements is regulated for forming microstructure during hardening containing 1.0-3.0 vol-% of graphite so that more than 20 but less than 100 graphite particles are accounted per square millimeter of area of observation of metallographic micro-section and residue contains martensite, 8-35 vol-% of eutectic carbides and at least 1 vol-% of finely-dispersed vanadium carbides. Then, melt is poured into mold for hardening. Roll thus obtained is subjected to heat treatment. Working part or jacket of combined roll is 10 to 150 mm thick. Structure of material of jacket includes 1.0-2.5 vol-% of graphite in finely- dispersed form with number of particles more than 20 per square millimeter of area of metallographic micro-section; 8.5 vol-% of eutectic carbides and 1-2 vol-% of vanadium carbide at smooth distribution, the remainder being martensite and admixtures stipulated by process; Shore hardness is70-90. Material of working part of rolls has low tendency to sticking at high resistance to attrition of entire thickness; carting material contains finely-dispersed smoothly distributed precipitation of graphite at low volume fraction and special carbides at small diameter of grains excluding separation and cracks on surfaces of rolls. EFFECT: enhanced efficiency and reliability. 30 cl, 4 dwg, 1 tbl