In order to make the bicycle bearing ball have good cutting performance and hardenability, and can have certain fatigue resistance after tempering, it needs to be spheroidized in the production process, and strict spheroidal structure is required. In the test spheroidized structure, it is observed whether there is flaky pearlite or sorbite structure and residual carbide network, and the size of the spheroidal carbide particles, whether the degree of uniformity meets the standard requirements or the like.
In order to obtain a uniform spheroidized structure, combined with the actual production process of the enterprise, through the analysis of the heating temperature and the influence of the original structure on the behavior of the carbide during the continuous cooling spheroidizing annealing process, the heating temperature and the internal tissue transformation of the bicycle bearing ball are known. There is a close connection between them.
The test results show that the structure obtained by the continuous cooling spheroidizing annealing process with heating temperature of 860 ° C is extremely uneven and is a typical superheated structure. A continuous cooling spheroidizing annealing process with a heating temperature of 760 ° C has no apparently underheated original flaky pearlite in the resulting structure. It can be seen that the heating temperature of the bicycle bearing ball is increased, the eutectoid decomposition temperature is lowered, the heating temperature is lowered, and the eutectoid decomposition temperature is increased.