Nanometer rare earth chromium alloy cast grinding ball and production method thereof

The invention relates to a nanometer rare earth chromium alloy cast grinding ball. Production of the nanometer rare earth chromium alloy cast grinding ball comprises the operation steps of steel scrap pretreatment, clean smelting, constant-temperature automatic casting, water-soluble medium quenching, low-temperature tempering, throwing aging treatment and mechanical property detection. Grains of the nanometer rare earth chromium alloy cast grinding ball are refined, the structure is compact and even, hardness HRC reaches 63 to 65, the impact energy absorption value is larger than 4 J/cm , and the breakage rate is smaller than 0.2%. Composite rare earth nanometer micropowder is adopted as a modification modificator, the forming number and speed of crystal nucleuses during molten iron condensation are remarkably increased, as-cast grain refinement and structure compactness of the grinding ball are achieved, and the hardenability and obdurability of the cast ball are improved; and copolymer (PAG) quenching liquid of polyoxyethylene and polypropylene oxide is adopted, the heat treatment cost is reduced, and meanwhile the problems of environment pollution and potential safety hazards in the heat treatment production field are solved fundamentally.