Microstructure control of ferrous driven part fabricated by warm precision forging

Abstract

A straight bevel gear for automobile differential unit is used to investigate the microstructures and dimensional change of warm forged part. Warm forging is the one of the good processes for near nest shaping since the warm forged parts have good microstructure, surface quality and others. Moreover, the process gives some advantages to reduce and eliminate following steps compared to the conventional hot forging. However, it is essential to have appropriate process parameters and then control the related metallurgical phenomena. Additionally, the control of dimensional accuracy of warm forged part is very important to reduce the following process, such as cold sizing or machining. SAE4130 is used as the material for bevel gear forging and high speed steel is used as die material. The hot compression tests are performed to select an appropriate warm forging temperature. A bevel gear is fabricated practically by warm forging using crank press. According to the microstructure evolution and FEM analysis of forging processes, the effective process data can be obtained.