Study on absorption and transport of carbon in steel during gas carburizing with rare-earth addition

The effect of rare-earth (RE) as a catalyst adding to carburizing atmosphere on absorption and transport of carbon is presented in this paper. The processing were carried out at 900°C for different time in a decomposition atmosphere of kerosene and methanol with and without RE addition. The compositions of carburizing atmosphere such as CO, CH4, etc. and the average carbon concentrations in 75 μm thick 08F steel foil were measured by infrared and chemical analysis, respectively. The surface activity and boundary transfer coefficient of carbon have been calculated based on the measured data. The results show that introducing RE into carburizing atmosphere increases the volume fraction of CO, CH4, etc. degree of dissociation of kerosene, carbon potential, surface activity and boundary transfer coefficient of carbon.