In the present work, the addition of ethanol to endothermic gas during the carburizing process of DIN 17NiCrMo7 steel gears was investigated with the objective of determining the impact on carbon surface concentration and microstructure. The materials were carburized at 870°C and 930°C, oil quenched, tempered and subsequently shot peened. Carburizing was carried out in a continuous industrial furnace for a total of 280 min. After quenching and tempering, the in-depth carbon concentrations were determined through quantitative chemical analysis and the resulting profiles were modeled in order to obtain carbon diffusivity constants. The amount of retained austenite and austenite grain size, determined by X-ray diffraction and optical microscopy, were found to increase with carburizing temperature. Residual stress profiles were also determined by X-ray diffraction before and after the shot-peening process. The microstructure of the specimens was further investigated by transmission electron microscopy, which revealed the presence of BCC martensite before and after shot-peening. The enrichment of the endothermic gas carrier with ethanol could be shown to be a viable option, allowing for surface concentrations of up to 0.8%C.
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