Vacuum Oxygen Decarburisation (VOD) of Steel
2026-03-23 159
VOD (VACUUM OXYGEN DECARBURISATION) is a manufacturing process that ensures the quality of stainless steel; it relies heavily on the rapid and accurate measurement of fluid composition at various stages of the process.
The real-time analysis provided by the ProC-TOF online mass spectrometer system enables the VOD process to optimise efficiency and product quality.
The role of the online mass spectrometer:
Maximise the oxygen flow rate to convert residual carbon in the steel into carbon monoxide and carbon dioxide; then stop the oxygen flow and increase the vacuum to remove dissolved gases from the molten steel at the correct time
The ProC-TOF industrial process mass spectrometer can rapidly identify the end of each VOD stage without compromising analytical accuracy.
In the production of secondary steel, taking vacuum oxygen decarburisation (VOD) as an example, this method can be used to produce high-quality low-carbon steels, such as stainless steel. Initially, the molten steel is placed in a vacuum environment of 1 millibar; at this point, oxygen is blown into the melt whilst argon is injected from the bottom of the vessel, ultimately achieving the removal of impurities.
Similarly, helium can be removed using the same method, with the mass spectrometer monitoring the entire impurity removal process.
VOD and RH are secondary steelmaking processes used to produce special steels; under vacuum conditions, carbon is reduced to extremely low levels (<0.01%) whilst ensuring that chromium is not oxidised.
As this process takes place under vacuum, the process mass spectrometer’s sample introduction system must operate across a wide pressure range: it incorporates valves and a capacitive monitor to ensure that gas at a constant pressure enters the ion source, thereby guaranteeing sensitivity and linearity.
As with the AOD process, the advantage of using process mass spectrometry lies in its ability to precisely determine the end point of decarburisation. Consequently, the carbon content of the steel produced fluctuates less: user studies on the use of process mass spectrometry indicate that the investment in the system can be recouped in just 3–5 months.