Distortion investigation of carburized and oil quenched pinion gears with different dimensions

Bow distortion of pinion gears from carburization and oil quench is one of the major distortion modes. Too large of bow distortion detriments the service performance of the pinion gear, and the inconsistency of distortion increase the scrap rate. One of the root causes of bow distortion is the nonuniform oil flow around the pinion shaft. However, the same degree of oil flow nonuniformity will lead to different magnitude of bow distortion for pinion gears with different dimensions. DANTE is a commercial finite element based heat treatment software for steel components, with the capability of modeling phase transformations, distortion, and residual stresses. In this investigation, a family of 3D pinion gears with different sizes are modeled. The part shape changes during austenitizing, carburizing, and quenching are analyzed, and the causes of bow distortion are summarized. With the assumption of inevitable oil flow nonuniformity of the quench tank, the relation between the pinon gear size and severity of oil flow nonuniformity is characterized by computer modeling, which is used as guidance in design of pinion gear configuration and quenching process.