M. Korecki, SECO/WARWICK S.A., Swiebodzin, Poland; P. Kula, R. Pietrasik, K. Dybowski, M. Krasowski, Technical University of Lodz, Lodz, Poland

Summary: Carburizing is the common method to obtain durability of power transmission components parts under the high dynamic forces. This is a two-stage thermo-chemical process. The transfer of the carbon follows from surroundings first (usually the atmosphere of carbon-carrier gases) to the surface of the material, and then carbon is then distributed into the depth of the material as the result of diffusion. Vacuum carburizing (LPC) has had direct influence on the first stage of the carburizing process, by allowing the transfer of practically an unrestricted quantity of carbon to the surface of the material. The speed and quantity of the delivered carbon at the beginning of carburizing until the moment of saturation of the austenite was a major improvement, resulting in reduced cycle times for LPC as compared with atmosphere carburizing, particularly for shallow layers. This effect diminishes for deeper carburizing therefore; future process development should concentrate on the second stage of the carburizing process with the end goal of acceleration of distributing the carbon into the depth of the material. SECO/WARWICK S.A. in conjunction with the Lodz Polytechnic University has developed a method using high-temperature vacuum carburizing FineCarb® supported by a new technology, PreNitLPC®, that produces a considerable acceleration not only of the transfer of the carbon to the surface, but its distribution in the case depth of the material with exclusion of the negative influence on crystalline structure and mechanical properties typically experienced when processed in high temperatures. The use PreNitLPC reduces carburizing time, by 2-3 times, depending on the thickness of the layer, the grade of the material and structural requirements.