3. Reduced-pressure refining processes

3.1 Principle

The principle of decarburizing alloys with a high chromium content, i.e. significantly higher than 9% Cr, was described in paragraph . It is based on lowering the partial pressure of CO either by diluting the CO with another gas (AOD process and derivatives), or by working under vacuum (VOD process). For the AOD process and its derivatives (essentially CLU and K-OBM-S), the neutral gas used for dilution also plays an important role in cooling the injection nozzles.

3.2 AOD process