The Study On Properties Of Low-temperature Plasma Nitriding New Processing Of Engine Valve

As we all know,the car's four components:body,engine,chassis and electrical equipment,which is the core of the car engine,called heart of the car,the performance requirements of engine are also increasing.Thousands of parts in the engine,car engine valve is functional parts,engine operation is an important precision parts,but also ensure that the engine has excellent power,fuel economy,work process stability and durability of key components,the pros and cons of the valve performance determines the service life of the engine,and the choice of materials and heat treatment processing technology determines the service life of the valve.The engine valve to have the following excellent performance:?1?has a high heat resistance and good corrosion resistance,surface hardness ?600HV_0.2;?2?has good mechanical properties;?3?has good anti-friction and wear resistance.In order to meet the special valve working conditions and technical requirements,valve materials are preferably substantially alloy steel,martensitic steel and austenitic heat-resistant steel.One of the necessary conditions for proper selection of materials are made valves,and the other necessary condition is to choose a suitable heat treatment process,plasma nitride as one of the surface technology,has been rapid development,after plasma nitride,parts of the surface wear resistance,fatigue resistance and corrosion resistance and strength,hardness has been greatly improved to meet the conditions of an engine valve.In this paper,as the material of choice 40 Cr,focusing nitriding valve research and propose new cycle plasma nitriding treatment process,respectively,at different temperatures and different times circular nitriding,exploring time and temperature parameters of the two processes circulating plasma nitriding the influence of the effect,and the conventional thermostat plasma nitriding,compared propose the optimal process parameters and handling.In this article,The modified layers were analyzed using micro hardness apparatus,microscopy,Scanning Electron Microscopy?SEM?,Energy Dispersive Spectrometer?EDS?,X-ray Diffraction?XRD?and friction abrasion testing machine,studying the plasma multi-elements penetrating surface modification permeation layer microstructure,composition and performance variation with process parameters,and with the Isothermal plasma nitriding process were compared.Experimental studies have shown that 40 Cr steel at a temperature of 550 ° C?the cycle time of 8 hours for plasma multi-elements penetrating of the sample surface hardness 1090HV_0.2 and permeability layer thickness is 0.325 mm,the sample has a high strength,high temperature and wear resistance,and having the engine valve condition,and compared with the new expensive valve material,40 Cr save the cost of the valve manufacturing.