27th IFHTSE CONGRESS & EUROPEAN CONFERENCE ON HEAT TREATMENT 2022

The 2050 carbon emissions targets aiming to limit the global temperature increase to 1.5°C are particularly impacting the industrial sector including heat-treatment processing with high energy intensity and significant needs of industrial gases. Thus the reduction of the CO2 emissions linked to heat-treating of metals is becoming critical and the related carbon footprint must be carefully evaluated for new investments as well as for retrofitting of production equipment.

Within heat treating, carburizing is one of the most important processes, widely used for surface hardening of low carbon steels. Usually carried out in batch or continuous furnaces, the related CO2 footprint of carburizing can be assigned to furnace heating energy, cooling and quenching energy, carburizing atmosphere generation, power consumption, peripheral devices and the processing itself.

This study presents an estimation of the CO2 footprint linked to different sources of furnace atmospheres used for atmospheric carburizing, like endogas and nitrogen/methanol and for different kinds of furnaces. A comparison with the low pressure carburizing process and the related CO2 footprint of the required hydrocarbon gas supply is then performed. Several solutions developed by Air Liquide to reduce the carbon footprint of heat-treatment atmospheres will be also presented.