Abstract
Acetylene and ethylene are generally used in vacuum carburizing in Japan today. Available directly from the pipeline, natural gas was applied to vacuum carburizing as the carburizing gas, to study the effects that changes in process parameters would have on carbon infiltration. A specimen (JIS-SCr420) was carburized at 1203 K, increasing the variable carburizing period to 3.6 ks. The carburizing gas was supplied pulse and continuous flows. In continuous flow, the furnace pressure during the process of carburizing was kept constant. The gas composition inside the furnace was analyzed by the gas chromatography in order to examine the extent of the carbon infiltration. The carbon concentration profile of the cross-sectional carburized layer was estimated by EPMA, and the amount of infiltrated carbon was calculated, in order to establish its relationship to gas composition. [Material: steel.]