In recent years, austempered ductile iron (ADI) has been used as an important engineering application material. Due to its superior and reliable static and dynamic properties, the unique advantages of noise reduction, and the attractiveness of low-cost, ADI automotive Parts justice is growing at a rapid rate of 25% every year, and the scope of application is expanding.

However, ADI is still a new type of material that is constantly expanding, and there are many applications and basic laws that need people to continue to explore. The specific research content and main conclusions are as follows:

First, discuss the influence of process specifications on the organization and performance of ADI for specific objects, and focus on exploring new methods, procedures and laws of ADI's heat treatment process to further improve the organization and performance.

Second, a new "two-step method" austempering heat treatment process is explored, that is, first isothermally at a lower temperature for a short time, and then rapidly rising to a high temperature isothermal. Compared with the traditional austempering process, the "two-step method" structure is significantly refined, while the volume fraction and carbon content of retained austenite in the matrix structure are not significantly different. Thereby, both the hardness and toughness are improved in performance, which is an effect that cannot be achieved by the ordinary quenching process.

Third, high-frequency induction hardening is used to strengthen the surface hardness of the high-toughness ADI. Two different surface induction hardening processes (primary induction hardening and secondary induction hardening) are used to focus on the influence of different induction hardening process specifications on the surface structure and hardness of ADI. The research results show that the secondary high frequency quenching greatly improves the surface hardness and the surface wear resistance without affecting the toughness of the core. This is of great significance to expand the application range of ADI.