Mounting evidence of customer benefits and process advantages have led to the common acceptance of the Low Pressure Carburizing process (LPC) with High Pressure Gas Quenching. The mechanism of the carburizing reaction at the parts' surface is not yet fully investigated. Mass spectroscopy and waste gas analysis can lead help to clearify the reaction mechanism of the most commonly used process gases. Continued development based upon practical experiences and new applications of the LPC process have been documented. By developing a Low Pressure Carbonitriding process, the benefits of LPC can be extended to non-alloyed or low-alloyed case hardening steels and tempering steels. By use of ammonia addition in the low pressure range the desired increase of surface hardness of low alloyed steels can be achieved. A further application includes the treatment of powder metallurgical sintered material. The main advantage of the LPC process is realized by the ability to process materials with open pores. A through carburizing of the entire work-piece can be avoided by using the LPC process. The process parameters can be optimized to the material specification. Finally, different furnace designs are presented. Special emphasis on the design of a continuous LPC plant was considered. Due to optimization of the gas quenching chamber by means of FE simulation the quenching capability of the quench chamber was significantly increased and the application limits of gas quenching were expanded. The high quenching rate enables increased core hardness despite of bigger parts dimension.
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