Casting and heat treatment of ductile iron piston

Ductile iron piston is mainly used in medium speed diesel engine. It is the key component of diesel engine. It needs to bear high compressive stress and thermal alternating load when working, and its working condition is very bad. Because the piston works at high temperature, metal parts are easy to fail in high temperature state, so cooling system is needed, which makes the piston structure more complex and requires higher material requirements.

The most widely used structure of piston is the integral thin-walled ductile iron piston. It is the most difficult piston to manufacture at present, and its difficulty is mainly reflected in the casting process. The strength and internal structure of piston casting are important factors for the service life of piston and even diesel engine.

Through the design of ductile iron piston material, the proportion of C, Si, Mn, s, p 5 elements is determined, and the alloy element Cu is increased To ensure the matrix structure and performance; to obtain qualified spheroidizing rate and ball diameter according to melting process, spheroidizing and inoculation treatment; to design casting process according to the structural characteristics of piston; to ensure sequential solidification and no internal defects of piston; finally, through heat treatment process design and heat treatment according to the process to obtain the metallographic structure and strength and hardness meeting the requirements of use. Finally, the ductile iron piston meeting the requirements of use is obtained.