Most excavators work in the open air, and the service environment is poor. The working mechanisms of excavator bucket, stick, boom and crawler roller are designed with multiple hinge points, which are connected and loaded through pin shaft and bushing. The pin shaft and bushing rotate relatively, transmit large load, bear transverse and lateral extrusion, as well as large impact and wear, and are required to have high strength, wear resistance and fatigue resistance. At present, carbon structural steel is often used as bushing material, and abnormal wear often occurs after quenching. The wear debris peeled off from the surface can enter the friction pair, causing the lubricating oil to be polluted and aggravating the wear failure of the bushing.
Due to poor wear resistance, the service life of excavator bushing is low, and it often needs maintenance or even replacement after 3 months of service. Therefore, traditional materials can not meet the performance requirements of excavator bushing. The preparation of wear-resistant bushing with new materials and new processes is of positive significance to improve the service life, reliability and work efficiency of excavator bushing and reduce its maintenance cost.
Isothermally quenched nodular cast iron is a kind of cast iron material with excellent properties. The nodular cast iron with specific composition is austenitized and then Austempered to form bainite and a small amount of austenite, so as to obtain excellent strength, wear resistance, good toughness and fatigue resistance. Isothermally quenched ductile iron is mainly used in the production of key parts of automobile, train and military products to replace cast steel and forgings. However, there are few reports on the treatment of excavator bushing with isothermally quenched ductile iron. Therefore, the nodular cast iron bushing was prepared by centrifugal casting process and treated by isothermal quenching nodular cast iron technology. The metallographic structure, mechanical properties and wear resistance of the bushing were analyzed and discussed in order to provide reference for its application.