Time of issue: 2021-10-14

1. High chromium ball quality index: Chromium content ≥10.0%, carbon content between 1.80%-3.20% are called high chromium balls. National standards require that the hardness (HRC) of high chromium balls must be ≥58, and the impact value ak≥3.0J/㎝2, if this hardness is reached, high chromium balls must be quenched at high temperature + tempering (the current domestic high chromium balls have two quenching methods: oil quenching and air quenching), if the hardness (HRC) is lower than 54 The following shows that the high chromium ball has not been quenched.

2. Medium chromium ball quality index: chromium content 3.0% to 7.0%, carbon content between 1.80%-3.20% is called medium chromium ball, impact value ak≥2.0J/㎝2, national standard requires medium chromium The hardness of the ball (HRC) must be more than 47. In order to ensure the quality of the steel ball, the chromium ball needs to be treated with high temperature tempering (to achieve the purpose of eliminating the casting stress). If the surface of the steel ball is still metallic, it indicates that the product has not been subjected to high temperature tempering treatment.

3. Low chromium ball quality index: chromium content 0.5% to 2.5%, carbon content between 1.80%-3.20% are called low chromium balls, the national standard requires low chromium ball hardness (HRC) must be more than 45, Impact value ak≥1.5J/㎝2, in order to ensure the quality of steel balls, low chromium balls also need to be treated with high temperature tempering (to achieve the purpose of eliminating casting stress), if the surface of the steel balls is dark red, it indicates that the product has been tempered at high temperature , If the surface of the steel ball is still metallic, it indicates that the product has no high temperature tempering treatment.