Research On Automobile Gear Steel 20MnCr5 And It's Heat Treatment Technology

China has imported many-advanced foreign technology of manufacturing automobile since reform and opening to the world. It greatly improved the technology and quality of our automobile. But our last goal is to manufacture automobiles using our own technology. For this, one of the important things is to research the gear steel of the automobile and it heat treatment technology.So according to the requirement of the import product, we entrusted Da Ye iron and steel works to smelt the gear steel-20MnCr5. After this we test the chemical composition, mechanical property, quenches hardenbility, grain-size, impurities and low multiple microstructures etc of the steel made by Da Ye iron and steel works, and also drifted the contents, method and the result of the test in detail. The test result show that the steel of 20MnCr5 made by Da Ye tally with the requirement of the import automobile technology.On this base, we conducted a series of heat treatment such as conditioning heat treatment and carburizing, and found out an optimum technology parameter of heat treatment. Thereby improved the machinability of gear blank and made it' s structure more even and stable and at the same time reduced the deformation of heat treatment. This paper also analyzed the influence factor of deformation of heat treatment and come to a conclusion of controlling the deformation according to the test result and analyses.At the same time, we also conducted the test of the contact fatigue and the bending fatigue of the material and studied system on the influence of the purity on the fatigue property of the gear steel.