The Relationship Research Of The Chemical Composition And Hardness Of Quenched Grinding Ball Based On The End Quenching Test

Grinding balls as the essential grinding medium of ball mill, along with the development of the modern selected mining, requirement of its performance diversification occurs and specifications range increases further. This trend lead to the material optimization selection and corresponding production process development, the hardenability of material in the process of grinding balls and quenching temperature field is the core of the problem.Based on this, the chemical composition of the steel grinding ball and the quenching hardness distribution of the sample data are summarized in this paper and4#heat grinding ball steel alloying steel with Si, Mn, Cr was made and the end quenching test for the experimental steel was carried out. The mathematical relationship between steel chemical composition at high carbon content and end quenching distance was established with the complex method for the given quenching hardness as followsE55=153xC2+3.5xSi2+32.2xCr2-1.9xCxSi+106.2xCxMn+172.2xCxCr+142xSixMn+4xSixCr+51.6xMnxCr-351.4xC-142xMn-173.5xCr+217.5E58=-331xC2-0.02xSi2+5.73xMn2+31.2xCr2+1.74xCxSi+184.2xCxMn+36.8xCxCr+7.1xSixMn+13xSixCr+524xMnxCr-75.7xC-20.6xSi-246.2xMn-95.3xCr+141.4Formula of the predicted results are in good agreement with the experimental results.By using the finite difference method and the principle of conservation of energy to end quenching specimen and grinding ball during quenching, programming on temperature field calculation was carried out and the results show that the surface cooling rate of grinding ball in different size are very big, and the cooling rate sharply reduce to1/4r depth range, falling slowly to1/2r depth, then changed little. With the increase of grinding ball diameter, the various characteristics of the position corresponding cooling rate significantly reduced.The hardness of corresponding location for the different specifications of the grinding ball with the computed same cooling rate were determined, the results accord with the rule of the same cooling rate the same quenching hardness were right,and confirmed the validity of the calculation of temperature field. On this basis, according to the same material under the same cooling rate, the same hardness rules, by end quenching test established the grinding ball hardness distribution, with different specifications quenching coincide withthe experimental results of the grinding ball.For4#steel with different specifications (Ф50mm, Ф60mm, Ф70mm, Ф100mm) grinding ball hardness distribution and100mm in diameter of grinding ballmicrostructure was analyzed, and the characteristics of different location and endquenching samples are in good agreement.Through the4#100mm steel grinding ball after water quenching microstructure andhardness test analysis, show that the temperature field calculation of the cooling rate of thegrinding ball is consistent with the experimental results.