The commonly used crankshafts at home and abroad are divided into two categories according to materials, forged steel and ductile iron. Compared with the two materials, nodular cast iron crankshaft has the characteristics of lighter weight, better castability, toughness, stronger designability and lower cost. Especially with the development of nodular cast iron alloying and isothermal quenching nodular cast iron (ADI), the properties of nodular cast iron have been continuously improved and widely used, For example, as cast pearlite ductile iron is used in light engines, while isothermal quenched ductile iron is used in high-power engines.
Cast crankshaft is a new type of crankshaft gradually rising in recent years, including cast heat treated crankshaft, austenitic isothermally quenched ductile iron crankshaft and as cast pearlite ductile iron crankshaft. Fiat Automobile Company of Italy has developed a series of high strength and Toughness Nodular Cast iron crankshafts, which have the highest comprehensive performance indexes among similar materials and represent the most advanced international level.
After normalizing, the nodular cast iron of grade gh90-5 can be used as the material of engine crankshaft. Austenitic isothermally quenched ductile iron technology is an important research in the field of cast iron metallurgy in recent years. In the United States, isothermally quenched ductile iron technology has completed preliminary theoretical and process research, and gradually put into production, forming a certain scale of practical products.
However, China is still in the stage of experimental research, and there are only a few reports on the application of single cylinder engine and four cylinder engine. As cast Pearlite Nodular Cast iron crankshaft has gradually replaced the traditional normalized nodular cast iron crankshaft. It has the characteristics that the matrix structure is completely pearlite and the number of graphite balls increases, so it has high mechanical properties as cast. Domestic EQ1092, Jetta, Fukang, Iveco, Santana and other models all use as cast crankshaft.