Study On The Composite Strengthening Mechanism Of High-frequency Quenching And Plasma Multi-elements Penetrating

With the rapid development of science and technology, people’s need for the operation performance and life of parts is higher and higher. It is increasingly paid attention to enhance parts’ properties to meet requirements in the modern society. The performance and working life to a great extent depend on the resistance abration, fatigue and corrosion of parts’ surface, which makes surface strengthening technology gaining increasing attention and develop so quickly. As an important composition of advanced manufacturing technology, surface strengthening technology contributes much to the development of advanced technology. Exploit and application of surface strengthening technology can help to develop manufacturing industry and remanufacturing industry,save energy and resources and reduce environmental pollution. Also surface strengthening technology is not only an important technical support of recycle economy but also an effective measure to achieve sustainable development in industry.As a clean and efficient surface heat treatment, induction heating can improve material’s surface properties significantly. The workpiece after induction heating has a fine grain size on its surface, which enhances the surface hardness, and the residual compressive stress on the surface can prolong the service life. Plasma nitriding process has come a long way but the difficult problem now is how to improve the nitrided speed and the properties of nitriding layer. Combine inducing heating and plasma nitride, we can use their advantages to the greatest extent. Quenched with high frequency before plasma nitride, the part’s surface is refined and lots of grain boundaries appear on the surface, which increases the volume fraction and enhances chemical reactivity of the surface. Meanwhile in hardening layer will exist a lot of dislocations, twin crystals, vacancies and other microdefects and all these can help to fasten the dynamic process of the spread and improve nitride efficiency.High-frequency quenching, plasma multi-elements penetrating and high-frequency quenching/plasma multi-elements penetrating are carried out to study the effect of different process parameters on the properties of 38 CrMoAl and 40 Cr. The modified layers were analyzed using microhardness apparatus, microscopy, Scanning Electron Microscopy(SEM), X-ray Diffraction(XRD) and friction abrasion testing machine. Theresults show that the samples get best hardness layers when the frequency is 20 KHz,heating power is 35 KW and the time is 6 seconds. The surface hardness of the samplestreated by high-frequency quenching/plasma multi-elements penetrating is thicker than the left two technology. Under the condition mentioned above, 38 CrMoAl and 40 Cr have best surface hardness and diffusion layer hardness gradient when multi-elements penetrated in 525℃ and 6 hours. High-frequency quenching can help the process of plasma multi-elements penetrating and the samples treated by both the two technologies have higher resistance to corrosion.