STEEL FOR GRINDING BALLS Russian patent published in 2008 - IPC C22C38/54 C22C38/32 

FIELD: metallurgy.

SUBSTANCE: steel contains carbon, manganese, silicon, aluminum, boron, copper, titanium, chrome, nickel, nitrogen, iron and admixtures, at following ratio of components, wt %: carbon 0.65-0.75, manganese 0.70-0.80, silicon 0.20-0.35, aluminum 0.010-0.025, nitrogen 0.005-0.025, titanium 0.005-0.010, chrome 0.40-0.50, nickel 0.01-0.30, boron 0.001-0.003, iron is the rest, at that admixtures are in following numbers: sulphur - not more than 0.030%, phosphorus - not more than 0.030% and copper - not more than 0.30%.

EFFECT: increasing of endurance and hardness of grinding balls.

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