Heat Treatment of Austempered Ductile Iron Gear

The optimizing experiments on the heat treatment process for the final transmission driven gear made of austempered ductile iron (ADI) were carried out using orthogonal test.The effect of the main alloying elements on ADI was analyzed,and the influences of the austempering process on the mechanical properties of ADI were discussed in detail,moreover,the strain hardening capacity of the ADI was also tested.The experimental results show that an optimized austempering process for the final transmission driven gear in tractor is of austenitizing at 900℃ for 2h and austempering at 290℃ for 1.5h.The ADI treated with this process has a microstructure with the matrix of lower bainite and retained austenite,and possesses an outstanding strain hardening capacity.