METHOD OF MAKING CAST IRON GRINDING BALLS Russian patent published in 1997 - IPC

FIELD: metallurgy. SUBSTANCE: method involves melting iron and simultaneously alloying it, casting necessary diameter rods, rolling rods to balls, subjecting them to quenching and annealing. Melt iron is modified by magnesium containing modifying mixture providing spheroidization of graphite. Before rolling rods are heated up to 950-1080 C; balls are made by rolling in helical rolling mill. Then balls are subjected to isothermal quenching from rolling temperature and to subsequent annealing at 280-320 C at using cast iron with next content, mas.%: carbon, 2.5-3.5; silicium, 1.3-2.8; manganese, 0.3-1; phosphorus, 0.02-0.08; sulfur, 0.001-0.015; copper, 0.15-0.8; chrome, 0.15-0.5; aluminium, 0.15-0.5; magnesium, 0.04-0.08; ferrum, the balance. Method provides manufacture of grinding balls having hardness no less than HRC 55, high wearability and shock resistance with price being by 20% lower than that of steel balls. EFFECT: enhanced quality of grinding balls.