| Die arrangement industry is the basic processing equipment of manufacturing industry. It is die arrangement that it could be arrived high precision, complexity, consistence, productivity, and low energy consumption, material consumption. Die arrangement industry is more and more important in the manufacturing industry. Die arrangement is used widely in the automobile, energy, machine, information, aviation aerospace, defensive industry and daily life. It is reported that die arrangement could be used to process 75% of roughing operations, 50% of precision works, 80% of parts in household appliances industry, and 70% of mechanical and electrical products. Die steel is the base of die arrangement industry. It is one of the most important material. The consume quantity of die steel is the most. It is estimated that the value of steel material used in die arrangement is near to 20% of total value of die arrangement industry. The value of die arrangement industry is 530 hundred million yuan and die steel is 106 hundred million yuan in 2004. The mount of steel consumed is about 88 ten thousand tons in die arrangement industry. Among them, most of it is die steel.Low alloy tool steel and high carbon high chromium steel, such as CrWMn, Crl2MoV and Cr12, are still classical steels in our country. The characteristic of the CrWMn steel is as follow. Quenching degree and wear resistance are determinate. Deformation is a little in the heat treatment process. Cooling speed of forged CrWMn steel has to be confined. Others, net carbides could be formed and break would be produced in the used of the die arrangement. The Content of chromium and carbon is higher. Eutectoid and eutectic point are moved to the left in the phase diagram. The amount of eutectic carbides is higher in the high chromium steel. High chromium steel is one of ledeburitic steels. Most of chromium are found in the compound of M7C3 in the steel. It is the main element produced asymmetry of the carbides. Fish bone eutectic carbides is found in the cast structure of high chromium steel. It would be turn worse with the slowed freezing rate and the aggrandized size of cast steel. The Fish bone eutectic carbides are not erase by heat treatment. It is the only way to break up the eutectic ledeburites by the forging operation.High carbon high chromium tool steel is one of high alloy steels. The content of alloy is higher in the steel. The elements of tungsten, molybdenum, and chromium are main alloying elements in alloy steel. The resource amount of tungsten of China is the most in the world. It is about 40% of the amount of existed in the world. The reservation of molybdenum of China is the second in the world. The statistical information indicated that the main alloying elements (W, Mo) of alloy steel, observed and used in the world, could only be used for 40～60 years. Included the prospective reserves, it also could only be used for 100 years at most. The chromium, one of main elements in alloy steel, is one of strategic materials. Chrome ironstone is serious short in the China. So saving alloying elements not only has significant strategic meanings, but also reducing the cost of steels. Considered the resources and price, low allow steels are paid attention to development in the world.Abrasion is one of main destroying forms of mechanical parts. The statistic showed by the World Friction Institute that 1/3～1/2 of the world primary energy sources was lost by abrasion. It was introduced that the cost of abrasion was about 2%～8% of GDP of the industrial country. It was imperfect stated, By five industrial departments such as metallurgy mine, farm equipment, coal, electric force, and building material, that spare parts required supplement was more than 1 million tons steels , which was about 15～20 hundred million RMB. About a half of steels was used for the production of spare parts every year in the mechanical industry. However, most of the spare parts were invalid owing to its low abrasive life. Abrasion invalidation initiated the surface of material. Compared with the smelted cold work die steel of high carbon high alloy steel, the content of the alloying elements is lower in the high alloy layer by the double glow plasma surface alloying technique. It could be saved the amount of the alloying elements and reduced the cost of the process. The study has scientific sense and practical significance for saved alloying elements and developed endurably of our country.Improved material surface property is an important method by surface modifying technique. It is a new way to improve wear resistance of surface of ferrous material in recent years. Double glow plasma surface alloying technique is one of surface modifying techniques. It is one of important way in the field of surface metallurgy technique. It is to increase the content of alloying elements in material surface and then improved the surface property by treatment followed.It is called plasma surface metallurgy HSS (high speed steel) formed surface HSS on the surface of low carbon and low alloy steel by double glow plasma surface alloying technique. It is alloy elements, such as tungsten and molybdenum, is infiltrated into the substrate and then solution and carburizing treatment is followed. High carbon high alloy layer is built up on the surface. The content of component is about up to HSS. The surface property of the substrate is approximate to property of HSS after high temperature quenching and tempering. It could satisfy the request on high temperature hardness and red hardness treated by plasma surface infiltration of W-Mo, carbonization, high quenching, and repeated high tempering. When the work pieces are used at ambient temperature, it is not need for high temperature hardness and red hardness. It would result in the waste of the energy in the condition used the W-Mo infiltrated and the alloying principle is not satisfied.Behind formed low-alloy HSS by double glow plasma surface W-Mo-infiltrated, it is researched to built Cr-Mo surface high wear resistant cold die LD steel by the technique in this paper. By the process of double glow plasma Cr-Mo infiltrated, plasma carburization, quenching between 980°C～1050°C, and lower or higher temperature tempering, it is to find a new way to build up a kind of gradient material and improve the property of wear resistance and red-hardness on low carbon or low alloy steel surface. It would meet the need for high wear resistance material in practical application. The study could develop the application field of the double glow plasma surface metallurgy technique.In this paper, It is research on Cr-Mo strengthened layer by double glow plasma surface metallurgy technique and treatment subsequently. In the study, they are researched deeply on influence of Cr-Mo infiltrated process, quenching temperature at different carbon content, wear resistance by cryogenic treatment, ion nitride, and N-C infiltrated.The characteristic is researched in this paper on double glow plasma surface metallurgy technique. They are been analysis on the plasma which are the feature of the cathode layer, affected electronic temperature and density. The preliminary search and study are made about physical characteristic and dynamic process of the plasma.In the paper, the results have been achieved:1. The high alloy layer of Cr-Mo could be obtained on the surface of low carbon steel by used double glow plasma surface infiltration of Cr-Mo technique. The content of constituent elements of the layer is about up to that of the high wear resistance cold work die steel. Subsequently ultra-saturated plasma carbonization is made, the carbon content of the surface is more than the calculated value of available carbon. Strengthened layer on low carbon steels is built up after the substrates are treated by quenching and low tempering. The shape of the carbides is granular and chunky structure. Compared with nonuniform distribution of carbides and complicated rolled process of high carbon high alloy wear resistance cold work die steel, the carbides of the alloyed layer are compact, uniform and disperse. The dimension of carbides in the surface layer is less than 1μm.2. After it is infiltrated of Cr-Mo and post-processing on low carbon steel, the main carbide styles of Cr-Mo strengthened layer are Cr23C6, Cr7C3, Mo2C, and Mo6C. 3. The depth of layer is built up with the increasing of the content of molybdenum of source cathode in the process of double glow plasma surface infiltration of Cr-Mo with acicular source cathode. With the infiltrated of molybdenum, the layer thickness increases.4. To improve the surface wear resistance, it could be treated by carburized, ion nitride, and N-C-infiltrated in the post-processing of Cr-Mo-infiltrated substrates. Compared with the process of formed low alloy HSS by double glow plasma surface W-Mo-infiltrated, it is more processes to meet the need of different request for wear resistance strengthened layer. It make friction coefficient reduce by the infiltration of the nitrogen element. Compared with friction coefficient of Q235 steel ion carburized, quenching and low tempering, that of the N-C-infiltrated substrate of Cr-Mo-infiltrated is reduced by 54.6%, that of the ion nitride substrate of Cr-Mo-infiltrated is reduced by 58.9%.5. The substrate, processed by Cr-Mo-infiltrated, ion carburized, quenching at 980°C and low tempering, is compared with that of Q235 steel ion carburized, quenching and low tempering. The friction coefficient is reduced by 11.6% and the average relative wear resistance is 2.6 times. The average relative wear resistance is 10.3 times in comparison with that of the T10 steel processed by quenching and low tempering.6. The substrate, processed by Cr-Mo-infiltrated, ion carburized, quenching at 1050°C and low tempering, is compared with that of Q235 steel ion carburized, quenching and low tempering. The average relative wear resistance is 1.5 times. The average relative wear resistance is 6 times in comparison with that of the T10 steel processed by quenching and low tempering. Resistance to tempering of the strengthened layer is similar to that of metallurgical M2, and it is higher than that of the high wear resistant cold work die LD steel.7. The substrate, post-processing strengthened treatment of Cr-Mo-infiltrated, is compared with that of Q235 steel ion carburized, quenching and low tempering. The substrate, processed by Cr-Mo-infiltrated, ion carburized, quenching at 980°C and low tempering, is compared with that of processed by Cr-Mo-infiltrated, ion carburized, quenching at 1050°C and high tempering. The substrate by cryogenic treatment is compared with that of non-cryogenic treatment. The abrasion experimental results show that the relative wear resistance of the former is higher than that of the later. Along with increased of cryogenic time, the relative wear resistance of the substrate is improved and the friction coefficient is reduced.8. In the equal potential glow discharge, when the voltage is 500-1000V and the working pressure is 30～100Pa, the electronic temperature is about 1～10eV and the electronic density is 1021m-3. The electronic temperature of the equal potential glow discharge is higher than one order of magnitude that of abnormal glow discharge at high pressure. The electronic density of the equal potential glow discharge is in the range of that of type of industry plasma (1012-1025m-3) and higher than that of the type of glow discharge (1014-1018 m-3). The equal potential glow discharge is one of abnormal glow discharge. It could produce more free electron on the surface of cathode. At the same time, it could not only inhibit free electron to move towards boundary, used closed assistant cathode, but also to enhance the temperature. As a result, the electronic density is increased in the equal potential glow discharge plasma. This is the two type of the equal potential glow discharge.9. In the non-equal potential glow discharge, the electronic temperature is not prominent affected by the source voltage and prominent affected by the piece voltage. When the source voltage is lower, the electronic temperature is affected distinctly by the work pressure. When the source voltage is higher, the influence is weakened gradually on the electronic temperature.
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