Wuhao Zhuang

Microstructure and Texture Evolution in Cold Rotary Forging of Spur Bevel Gears of 20CrMnTi Alloy Steel

The microstructure of cold rotary forged gears greatly affects their working life. Therefore, the aim of this study is to reveal the evolution of microstructure and texture that occurs during the cold rotary forging of spur bevel gears of 20CrMnTi alloy steel. The evolution of grains of the gear tooth is investigated through optical microscopy. By employing scanning electron microscopy and electron backscatter diffraction, the evolution of the cementite particles and the texture of the gear tooth is also revealed. The results indicate that the grain size distribution is non-uniform from the tooth profile to its center. The cementite particles in the tooth profile are finer and more uniformly distributed than those in the tooth center. After cold rotary forging, the tooth center has a combination of α- and γ-fibers, and the γ-fibers are more developed than the α-fibers, while most of the components in the tooth profile are assembled along the α-fibers.

Distribution of Microstructure and Vickers Hardness in Spur Bevel Gear Formed by Cold Rotary Forging

Cold rotary forging is a novel metal forming technology which is widely used to produce the high performance gears. Investigating the microstructure and mechanical property of cold rotary forged gears has a great significance in improving their service performance. In this study, the grain morphology in different regions of the spur bevel gear which is processed by cold rotary forging is presented. And the distribution regulars of the grain deformation and Vickers hardness in the transverse and axial sections of the gear tooth are studied experimentally. A three-dimensional rigid-plastic FE model is developed to simulate the cold rotary forging process of a spur bevel gear under the DEFORM-3D software environment. The variation of effective strain in the spur bevel gear has been investigated so as to explain the distribution regulars of the microstructure and Vickers hardness. The results of this research thoroughly reveal the inhomogeneous deformation mechanisms in cold rotary forging of spur bevel gears and provide valuable guidelines for improving the performance of cold rotary forged spur bevel gears.