Study On The Kinetic Mathematical Model Of Normalization In Ductile Iron And Optimization Of Process

During the later decade, the production of ductile iron has increased continuously in the whole of world, and the ductile iron is applying to the automobile industry widely with the strong tendency of replacing cast steel and gray iron because of its high strength and plastic property. The modern casting methods and crafts of ductile iron, that can be sure of the dimension accuracy, compact texture, well spheroidisation and refined graphite and grain of casts due to the high stiffness of model and the rapid cooling, have deeply developed in the past fifty years, and now are putting into practice, such as: horizon continuous metal cast process, mental mold covered sand process, quite casting process, spray forming etc.In this work, the technologic question on the quality of ductile iron camshaft, existing in the production of mental mold covered sand process, has been generally and detail analyzed and discussed. In the end, the appropriate improved pattern has been put out.The continuously cooling experiment has been carried out in this work. The influence of continuously cooling rate on the microstructure of ductile iron has been discussed while the volume percentage of pro-eutectoid ferrite that formed under different cooling rate has been determined. On this base, the kinetic mathematic model of relation between the volume percentage of pro-eutectoid ferrite and the continuously cooling rate has been established. Using this model, it is obvious that the percentage of pro-eutectoid ferrite changes as the cooling rate changes. When the...