THE FORECASTING OF THE EFFECTVE THICKNESS OF A TEMPERED BY HIGH FREQUENCY CURRENT LAYER FOR THE "REVERSE IDLER GEAR SHAFT" DETAIL ACCORDING TO THE 45 STEEL ESTIMATED HARDENABILITY
The study is performed on the example of “Reverse idler gear shaft” part made of 45 steel and covers the development of methodology of forecasting the effective thickness of a tempered by high frequency currents layer with the help of estimated hardenability, which uses data of metal acceptance test by chemical composition and grain size. The research is caused by the necessity of increase of the tempering equipment capacity and the reduction of working time for the estimated hardenability determination. The work was performed taking into account the lack of research in scientific literature containing the detailed description of methodology for forecasting of hardness and effective thickness of tempered with high frequency currents layer for the parts made of 45 steel using the estimated hardenability. In this research, the authors, firstly, analyzed the heat chemistry, secondly, determined the values of hardness depending on the layer effective thickness, and, thirdly, built the estimated hardenability curves using the Daido Steel (DS) method and the layer effective thickness dependences on the estimated hardenability. It was determined, that the above-mentioned dependences allow forecasting the layer effective thickness with the desired precision prior to the “HFC hardening” operation that serves as the basis for the proposed methodology implementation into production. The developed methods allow the following: - to reduce the working time for determining the effective thickness of a tempered with high frequency currents layer, as compared to the control in a specialized laboratory; - to eliminate in the existing production the necessity of control of the layer effective thickness after the “HFC hardening” operation, and therefore, to avoid the equipment downtime due to the use of data of the supplied metal acceptance test by chemical composition.