CarbideDispersionCarburizing(CDC)ofFe-Mo-VBased.PDFVIP

ISIJ International, Vol. 46 (2006), No. 2, pp. 310–315 Carbide Dispersion Carburizing (CDC) of Fe–Mo–V Based High-speed Steels Ikuo OHNUMA, Ryosuke KAINUMA and Kiyohito ISHIDA Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579 Japan. (Received on September 26, 2005; accepted on November 30, 2005) The carbide dispersion carburizing process was applied to Fe-based high-speed steels, which contained multiple carbide-forming elements, Mo and V. Fine carbides precipitated during the carburization and the dispersed particles in the Fe–Mo–V–C alloys heat-treated at 1 200°C were identified as VC, (Mo, V)2C, and (Fe ,Mo)6C, which behave as effective inhibitors against the grain growth of austenite and as reinforcers re- sulting in increased hardness of the martensitic matrix. The maximum Vickers hardness of the Fe–10Mo– 5V–2.05C alloy quenched from 1 200°C and tempered at 600°C achieved values of 1 100 and 1 000, respec- tively. Thermodynamic calculation of the Fe–Mo–V–C quaternary system proved to be useful for optimizing the composition of carbide forming elements, the carburizing conditions, and the microstructure of carbur- ized and solution-treated alloys. KEY WORDS: high-speed steel; carburization; carbide; heat treatment; phase diagram; CALPHAD. concentration profile of dissolved carbon can be obtained. 1. Introduction When a certain amount of CFEs is added to the starting Carburization is widely applied in various kinds of steel material, the carbon content at the surface exceeds the solu- to improve the wear resistance of parts of indus