The falling ball tests were carried out on the phi 125 mm diameter Carbidic Austempered Ductile Iron (CADI) grinding balls with Mn content of 2.0wt.%, 2.3wt.%, 2.6wt.% and 3.0wt.%, respectively, and the kind of grinding ball with the most serious spalling was selected for stress simulation. The stress distribution between four grinding balls in the elbow of the falling ball test device when they collided with each other was simulated based on ANSYS. Results of the falling ball tests show that the spalling and mass loss of a CADI grinding ball increases with the increase of Mn content, and the CADI grinding ball with 3.0wt.% Mn shows the most obvious spalling and mass loss. The simulation results of stress distribution of a CADI grinding ball show that the maximum impact stress does not appear in the center of the contact area, but in the annular area (inner diameter of similar to 20 mm and outer diameter of similar to 50 mm) in the section with a depth of 5-15 mm below the grinding ball surface. The actual spalling of the ball is consistent with the simulation results, and the oxide-based impurities in CADI grinding ball accelerate the spalling of the grinding ball in service.
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