What is the effect of heating temperature on the spheroidized microstructure of the bearing steel ball?

- Apr 28, 2018-

There are various methods for obtaining a ball-shaped spheroidized structure of a bearing steel using heat treatment. Among them, the continuous cooling spheroidizing annealing method using the isothermal transformation of the bearing steel ball spheroidizing annealing is most widely used in the spheroidizing annealing of the high carbon chromium bearing steel in the metallurgical enterprises.


Spheroidizing annealing of bearing steel balls is to obtain good cutting performance and hardenability, and it should have fatigue resistance after tempering. Therefore, it is one of the extremely important processes, and requires strict homogenization of spherical structures, so the ball is inspected. In the observation of the chemical structure, it is observed whether flaky pearlite or sorbite structure and residual carbide network are present, and the degree of particle size of the spherical carbide is consistent with the standard requirements.


When the bearing steel ball is processed, in order to obtain a uniform spheroidized structure, combined with the actual annealing process of the enterprise, the influence of the heating temperature and the original structure on the carbide behavior in the continuous cooling and spheroidizing annealing process is analyzed, and the continuous cooling is described briefly. The relationship between the behavior of the carbides during the annealing and the heating temperature and the decomposition temperature should also be followed by the relationship between the heating temperature and the transformation of the structure.


To investigate the heating temperature of the bearing steel spheroidized structure, we should pay attention to the test method: when the experimental materials used in the hot-rolled state of the bearing steel, specifications for the Փ11, Փ15, Փ21 bar sample, with the annealing furnace normal annealing and in the corresponding specifications And on the fixed bar, remove some of the sample in the box furnace for high and low temperature annealing. In this way, the experimental analysis of the combination of actual production and simulation by the annealing furnace and the box-type electric furnace is carried out. Before the temperature is lowered in each stage of the annealing process, the sample is extracted by water quenching to observe the change process of the structure.


To explore the heating temperature of the ball bearing steel structure test process, according to the corresponding production process, the organization after annealing is very uneven, in order to find the corresponding annealing of the organization, the heating temperature of another test process should be selected as At 860°C and 760°C, similar simulated microstructures and corresponding heat treatment processes were found through simulated annealing tests in order to expect a better bearing steel spheroidized structure.