Research On 38CrMoAl Steel Hollow Cathodic Auxiliary Plasma Nitrding Technology And Theory

38CrMoAl steel is a kind of medium-carbon alloy steel with high surface hardness, abrasive resistance, fatigue strength and good heat resisting property, corrosion resistance, which is applied broadly in engineering.38CrMoAl steel is also a kind of common nitriding steel which is widely used in higher demands proposed nitriding parts which need high surface hardness, good abrasive resistance and inner area intensity.Because of the advantages of production cycle, Environmental protection, energy conservation, no need for further working, excellent adjustability on plasma nitrding gas and nitrding layers composition and so on, plasma nitrding plays an irreplaceable role in produceing elaborate high property parts. What is more, hollow cathode auxiliary plasma nitrding is of broad market prospect because of the the advantages of efficient and energy saving.According reasearching on the different influence factors on plasma nitrding layers and the real experiment equipment, nitrding time, nitrding temperature and electrode of nitrding sample are choosed to be influencing factors of orthogonal experimentation with 3 factors and 3 levels, the best technology of 38CrMoAl steel hollow cathode auxiliary plasma nitrding is researched by which. Besides, micro hardness, surface roughness, surface topography, hardness gradient and nitrding layer thickness under the the best nitrding technology are set out.The testing results show that the micro hardness of hollow cathode auxiliary plasma nitrding layer under the best technology rose noticeably which is 4 to 5 times micro hardness before nitrding. Besides, surface roughness of the plasma nitrding sample is as the same as that before, which can be used needing no more sueface treatment. What is more, there is a 3-μm-thickness white layer in the surface of nitrding sample, and the whole depth of nitrding layer reaches 300μm, the nitridng layer comprisesεandγ'phase. So, the capability of 38CrMoAl steel plasma nitrding layer satidfies the actual industrial demands.In this paper, each chemical and phisical reaction, interstitial and reaction diffusion process of activated nitrogen atom is analyzed from the theory. Conditions ofγ'-a andε-γ' phase interface processing from surface of nitrding sample to interior is studied thermodynamically. Because of the defect of nitrogen potential definition gived in industry, activity formulas of nitrogen are obtained, which provide universal significance and certain theory guidance.