Preform optimization and microstructure analysis on hot precision forging process of a half axle flange

Precision forging process of a half axle flange was studied based on numerical simulation and experiment. The preform shape was optimized to avoid the forging defects, and the microstructure of initial billet and obtained forging was also examined. The results showed that the unreasonable material flow behavior can cause the defects of laps and under-filling during final forging process. Through increasing the load surface and adding transition chamfer in the joint having dramatic variation of cross section, the preform shape was optimized and the forging defects were avoided. Moreover, the forging load was reduced to one third of the initial process after optimization. Both the grain growth and the recrystallization were observed during hot forging. However, due to the non-uniform distribution of strain, stress, and flowing velocity, the grain size and precipitation of cementite varied significantly in different positions of the obtained forging part.