Investigating the Effect of Induction Parameters for Optimizing the Heat Treatment of 4620 AISI Steel in the Steering Wheel Pinion

Abstract

This paper presents a new method for optimizing the heat treatment of 4620 AISI steel in the steering wheel pinion. In the first place, the pinion was carburized and quenched in oil at 120 ° C. The second step was stress-relief and temper by induction. Finally, a machining operation was carried out to make thread and spline. According to the standard, the surface hardness of spline should be 37-45 HRC. Meanwhile, the pinion should machine easily to prevent fast-failing of the machining tools. As a result, the mentioned procedure was repeated with different induction parameters. The most important induction parameters for this research were the power of induction and the coil motion speed. The diameter of the thick part of the pinion has a major role in the hardness of spline because of the thickness of the carburized layer after the machining process. Thus, this parameter was included in the experiments too. According to the results, it was found out that by increasing the induction power, the spline surface hardness decreased. In addition, the effect of high speed of coil motion was more than its lower one. This effect increases the hardness of spline surface intensely. Based on these findings, it was concluded that using low power induction, high coil speed and small diameter lead to lower costs, increased speed of the process and good machining ability. This study demonstrated that the proposed technique can be considered more suitable than the existing procedure.