Quality index of cast steel ball

High Chrome Grinding Media Ball Quality Indicators

Cast steel balls with chromium content ≥10.0% and carbon content ranging from 1.80% to 3.20% are defined as high chromium balls (high chrome grinding media balls). As the premium wear resistant steel ball for industrial grinding, national standards mandate that the hardness (HRC) of high chrome grinding media balls must be ≥58 and the impact value ak≥3.0J/㎝². To reach such high hardness and wear resistance standards, high chromium balls must undergo professional high-temperature quenching and tempering processes—currently, domestic quenching for this type of grinding steel ball includes two mainstream methods: oil quenching and air quenching. A key quality inspection criterion: if the tested hardness (HRC) of a high chrome grinding media ball is below 54, it indicates the product has not undergone the required quenching treatment, failing to meet the quality standard of a qualified high hardness grinding ball.

Medium Chrome Grinding Balls Quality Indicators

Medium chromium balls, a common type of cast steel ball for mining and cement grinding, feature a chromium content of 3.0% ~ 7.0% and a carbon content of 1.80%-3.20%. National quality standards require this grinding media to have an impact value ak ≥ 2.0J/㎝² and a hardness (HRC) ≥ 47. To ensure the structural stability and service life of the cast steel ball and eliminate casting stress generated during production, all medium chromium balls must be subjected to high-temperature tempering. A simple and intuitive appearance inspection method for this grinding steel ball: a dark red surface indicates the product has completed high-temperature tempering; a retained metallic luster on the surface means the high-temperature tempering process was not performed, and the product is unqualified.

Low Chrome Grinding Balls Quality Indicators

Low chromium balls—an economical cast steel ball for general grinding applications—have a chromium content of 0.5% to 2.5% and a carbon content of 1.80%-3.20%. National standards specify that the hardness (HRC) of this grinding media must be ≥ 45 and the impact value ak≥1.5J/㎝². Like medium chromium balls, low chromium balls also require high-temperature tempering to eliminate casting stress and ensure the basic performance of the grinding steel ball. The same appearance judgment standard applies: a dark red surface verifies that the high-temperature tempering process is completed, while a metallic surface proves the product has not been tempered at high temperature and does not meet the factory quality requirements for cast steel ball grinding media.