The high chromium cast iron products treated in this paper are made of hot metal with a temperature of 1550 °C, which are cast into 80mm diameter high chromium cast iron grinding balls in a cold mould. The chemical composition of the material is shown in Table 1.

In order to analyze the microstructure of the cast ball treated by the MQ-P-T process, the CCT curves of Fe-2.4C-12Cr white cast iron, continuous cooling transformation (CCT-RRB- curves, and the microstructure and proportion curves of the steady-state materials were calculated by Jmatpro software, as shown fig. 1. It can be seen from Fig. 1 that in order to avoid the precipitation of pearlite and ferrite, the residence time of the material in the temperature range of 520-780 °C should be shortened as far as possible, and the cooling rate of the sample should be higher than 1 °C/s. At the same time, because of the high chromium cast, the iron is easy to be quenched and cracked, so it is not suitable to be cooled at too high a continuous cooling rate.

After being treated by the MQ-P-T process, the high chrome cast iron grinding ball was subjected to mechanical and performance measurement: the hardness sample of 10mm x 5mm x 80mm was cut along the radial direction, and 500RA type Lo measured the hardness, and the standard impact sample of 10mm x 10mm x 55mm was cut along the radial direction, the impact test was carried out on the PTM2200-D1 automatic impact test machine. The specimen, microstructure, microstructure, and microstructure were observed with Nikon Eclipse MA200 optical microscope (OM). The scanning (SEM) is carried out on the Jeol Company’s Sirion 200 model equipment; the voltage is selected 10kV. Tem sample in Jeol Jem 2100 transmission, electron microscope, upward, observation, acceleration, voltage selection 200 kV. Using the residual stress testing equipment produced by Jinan Sigma Company, the residual stress on the surface of the cast ball was measured by the blind hole method.