Hoganas AB, Bruksgatan, Sweden, announces the implementation of a combined vacuum sintering and low pressure carburizing (LPC) furnace technology to provide more cost-efficient and higher quality PM component solutions. LPC also results in reduced distortions during the heat treatment process and consequently improves the overall dimensional quality and tolerances of PM components.
Chromium-alloyed powders provide a cost-efficient way to manufacture high-performance applications. However, PM components produced from such powders cannot be surface hardened by conventional gas carburizing and oil quenching. To meet the stringent requirements on quality and dimensional accuracy, an alternative is to use low pressure carburizing (LPC) with pressurized gas quenching.
By alternate injection of acetylene (for carburizing) and nitrogen (for diffusion) at low pressure (5-10 mbar), the parts are carburized by decomposition of acetylene at the surface, followed by diffusion of carbon to an appropriate carburizing depth. After the carburization, the parts are moved to the quench cell where they are quenched in nitrogen at pressure up to 20 bar. The high pressure nitrogen in the quench cell is circulated by turbines through heat exchangers to obtain high cooling rates. The furnace allows a very precise control of the carbon profile and, thanks to the gas cooling, also reduced distortion compared to oil quench.
