Gray cast iron has the advantages of good castability, low casting cost, easy cutting and excellent shock absorption. It is widely used and manufactured all kinds of brake parts. When the vehicle is braked, the brake drum and the matching pair generate fierce friction, and a large amount of heat energy generated by friction is absorbed by the brake drum, which increases the working surface temperature of the brake drum, and then cools rapidly due to the excellent thermal conductivity of the metal. Such frequent braking, on the one hand, causes serious friction and wear of the brake drum, reduces the thickness of the brake drum wall, and affects the braking performance; On the other hand, due to repeated alternating cold and heat, a large number of thermal fatigue cracks sprout on the inner surface of the brake drum, and the further expansion of the cracks eventually leads to the rupture of the brake drum. Therefore, the research on improving the thermal fatigue resistance and wear resistance of gray cast iron has become the primary problem to improve the service life of brake drum. Through careful analysis of the microstructure of gray cast iron brake drum, it is found that due to the differences of chemical composition and solidification conditions, there are great differences in the type and content of graphite, which has a direct impact on the performance of brake drum.
Therefore, considering the various properties of gray cast iron, combined with the bionic coupling theory, the biological model with excellent fatigue and wear resistance in nature is selected, and the bionic coupling treatment is carried out on the surface of gray cast iron samples with different graphite types and carbon content by laser melting technology, so as to study the thermal fatigue resistance and wear resistance of laser bionic gray cast iron materials. The main contents of this paper are as follows:
- By casting gray cast iron with different graphite types and laser bionic surface treatment, firstly, the response of gray cast iron with different graphite types to laser is analyzed, and then the influence and mechanism of laser bionic gray cast iron with different graphite types on thermal crack initiation and thermal fatigue crack propagation are studied to find out the type of gray cast iron with the best thermal fatigue resistance.
- The wear test of bionic gray cast iron was carried out to study the effect of different graphite types on the friction and wear of laser bionic gray cast iron.
- Under the condition of controlling the same graphite type, the effect of carbon content on the thermal fatigue properties of laser bionic gray cast iron was studied, and the thermal fatigue fracture was analyzed.
- Through the same wear after thermal fatigue of laser bionic gray cast iron with different carbon content, the wear amount is counted, the wear morphology is analyzed, and the effect of carbon content on the wear resistance of bionic coupling gray cast iron after thermal fatigue is studied.