Carburizing of steel at high and low pressures

Important results from the project

The aim of the project was to compare different combinations of components (forged or manufactured via powder metallurgy (PM)) and heat treatment processes (conventional atmospheric carburizing or low pressure carburizing (LPC) with regard to carburizing ability and environmental impact. The goal was to investigate whether there is an environmental advantage of manufacturing and heat treating components via PM+LPC. An in-depth life cycle analysis (LCA) shows that the combination can lead to a significantly reduced environmental impact, expressed as CO2 equivalents.

Expected long term effects

The project results point to a significant environmental advantage in choosing the PM+LPC combination. Expected effects are that more components can depart from conventional manufacturing and heat treatment and be adapted to a modern process with lower climate impact. However, continued comparison and development of the process for new steel types, component geometries, heat treatment recipes and conditions for the heat treatment itself (furnace type, country in which the heat treatment takes place) etc. is required to demonstrate and increase the competitiveness of PM+LPC.

Approach and implementation

The project has worked well and consisted of RISE (project management), Swerim (material analysis), Härdservice (heat treatment, data collection) and Höganäs (materials, material analysis, life cycle analysis). Initially, several heat treatment trials were carried out at Härdservice to tune the process parameters of LPC of PM components as this is relatively unexplored compared to conventional case hardening of forged components. After that, real heat treatment trials took place with parallel data collection and life cycle analysis as well as supplementary material analysis.