Research On The Forming Process And Microstructure Evolution Of Heavy Commercial Vehicle Front Axle

Front axle is the most important security pieces of heavy commercial vehicle, and bears high alternating load in motion. In order to ensure the safety of the vehicle, the mechanical properties requirements are higher and higher. Precision roll forging-die forging is the typical front axle forging process. But the process development is difficult, when precision roll forging, metal flow situation is complex. Precision roll forging relys on the development of practical experience and repeated experiments. During the new product development, a lot of resources and energy were wasted, the product development cycle was long and the cost was large. Therefore, it is necessary for the research on the process of roll forging to optimize the process and shorten the production development cycle. Meanwhile, the microstructure of materials directly affects the mechanical properties of the front axle. In order to obtain excellent mechanical properties of the front axle forgings, research on the influence of deformation and heat treatment has big significance. In this paper, combine the FEM and the physical experiment, the precision roll forging, die forging and heat treatment of the heavy commercial vehicle were researched. The metal flow, temperature field, stress-strain field, austenite grain size, microstructure distribution information were analyzed and forecasted intuitively. Details works are as follows:(1) The precision roll forging and die forging process of the heavy commercial vehicle: According to the current situation of the precision roll forging, the roll forging method has been improved. Through this method, the heavy commercial vehicle axle forming process was designed, and qualified products were successfully produced in the first experiment.(2) The evolution of the austenite grain size:Through physical experiments the evolution of austenite grain growth model was established. Combined with literature provide data, the dynamic recrystallization, static recrystallization and grain growth were considered to predict the evolution of the front axle austenite grain size.(3) Microstructure transformation of the heat treatment process:Combined FEM and physical experiment, front axle finite element model of heat treatment microstructure transformation was established and the microstructure transformation was researched.It's found that the improved method could quickly and qualified to complete the precision roll forging process. Grain size evolution model could accurately predict the trends of austenite grain size during forming and heat treatment. Dynamic recrystallization refinement is the main reason of the change of grain size change. Microstructure transformation model could accurately predict the changes of the quench process and the Martensitic transformation plays a major role.