Carburizing, nitriding and carbonitriding

1. Mild steel carburizing, nitriding and carbonitriding carburizing is one of the traditional surface chemical heat treatment, carburizing steel ( Low carbon low alloy steel, high temperature low carbon high alloy carburizing steel) After carburizing and quenching on the surface of high toughness of hard wear-resisting, the core. Carburizing process development on the one hand is the improvement of carburizing medium, such as add increase the infiltration rate of additives, the strong permeability - - - - - - - The spread of the cycle of process improve the seepage velocity, improve permeability layer organization, etc. Appeared with the development of vacuum technology, vacuum low pressure carburizing and plasma carburizing. Ipsen companies such as development of acetylene low pressure carburizing process is under 10 mbar under low pressure, with acetylene carburizing medium in vacuum furnace. Is characterized by faster and less uniform permeability layer, carbon black, permeability after light; In addition, the requirements for permeability layer thinner punching needle bearing parts carbonitriding or carburizing, carbonitriding layer depth and the composition of control and how to improve the penetration rate is a big problem, using vacuum low pressure carburizing technology will be used to solve these problems. Plasma carburizing of high alloy carburizing steel can improve the seepage velocity, reduce the formation of the surface rough carbide. For low carbon steel needle roller bearing inner and outer ring and cage using nitriding or carbonitriding, can improve the wear resistance and corrosion resistance, to reduce the friction coefficient. 2. High carbon chromium bearing steel carburizing and carbonitriding of high carbon chromium bearing steel is generally the overall hardening, the residual stress after quenching for surface tensile stress state, easy to cause the quenching crack, reduce the use of the bearing performance. Through carries on the carburizing, nitriding and carbonitriding, improve the surface of carbon, nitrogen, reduce the surface layer of Ms points, in the process of hardening surface after transformation and the formation of a surface compressive stress, improve the wear resistance and rolling contact fatigue performance. Recent studies also show that high carbon chromium bearing steel after carburizing and carbonitriding also can improve the bearing under the condition of the pollution of the contact fatigue life. Generally, when quenching heating, by controlling the atmosphere of carbon ( N) Potential, can achieve the above purpose. But if the supernormal carburizing of high carbon chromium bearing steel ( Carbon potential & gt; 2%) , you must increase the machining allowance, remove after carburizing and quenching the rough surface of the carbide. 3. Process control carburizing ( Nitriding or carbonitriding) Detection and control is the key parameter of the atmosphere, the first is to use grain CO2 infrared analyzer, mainly using oxygen probe to detect carbon potential ( Or nitrogen potential) , the reaction speed, can be real-time monitoring, cooperate with CO2 infrared analyzer or other measures for measuring ( Such as development of ipsen HydroNit probe) The carbon potential ( Or nitrogen potential) A precise control. On the other hand is carburizing process control ( Nitriding or carbonitriding) Computer simulation of the process of control. Carbon in steel transfer and diffusion of computer simulated began in the 1980 s, after the further development of the man-machine dialogue software ( 碳水化合物, o- Prof） , so people can live to calculate different steel grade at any time in the carburizing process of carbon transfer and diffusion velocity. The software takes into account the temperature, the influence of the process parameters such as the carbon potential, can achieve the desired surface carbon content of the calculation of the process parameters and thick of carburized layer, and can according to the change of parameters in the process to automatically adjust the carbon potential, or the interference carburizing process parameters such as time, artifacts in order to achieve a predetermined requirements. Recently, and launched a 'Carb - o- Prof- Expert 'Expert system. The software integrates most of carburizing steel carburizing and quenching and knowledge of the physical metallurgy, equipment performance, technical requirement of workpiece data, as long as the input to the computer steel grade, weight, geometry size of workpiece, hardenability and the request of carbonitriding layer and furnace type data, such as computer will output a carburizing process, and implement the process automatically.