Carburizationofsteels-Anoverview-NISCAIROnline.PDFVIP

Indian Journal of Engineering Materials Sciences Vol. 1,August 1994, pp. 221-228 Carburization of steels-An overview P C Prasannan- Powder Coats India, Khira Industrial Estate, Santa Cruz (W), Bombay 400 054, India Received 27 December 1993; accepted 16.March 1994 A high carbon upper layer is produced by diffusing carbon and the carburized steel is used in gears, crankshafts where high ware and tare occurs. The thermodynamic, kinetic and transport phen- omenon occurring during carburization is studied. Importance of thermochemical phase diagrams to determine the stability region of the oxides and carbides is illustrated. The relationship between the composition of the carburizing atmosphere and the carbon content of the steel is brought out Deve- lopment of a suitable heat treating environment for obtaining the correct penetration depth is at- tempted. Mechanism of carburization, kinetic and reaction mechanism of decomposition of gas mix- ture on the stcelsurface is described. Models for predicting carburization depth are reviewed. A dif- fusion model is proposed which is applicable to any diffusion-cum-reaction process. Application and hazards of carburization are explained. Carburization is a process by which carbon is analyzed by a Gc. The methane content is con- transferred by molecules like CO, CO2, CH4 and tinuously analyzed by an IR gas analyzer and the other hydrocarbons into the metal matrix mainly dew point by an ALNOR