Definition - What does Vacuum Degassing mean?
Vacuum degassing is a technique of removing dissolved gas from a liquid solution by lowering the pressure inside a vessel containing the solution. Vacuum degassing is often utilized in:
- Water treatment
- Laboratory testing
- Soil purification
Vacuum degassing is the only way to make certain grades of steel that are particularly useful in the automotive, aerospace and railroad industries.
This process is also utilized for analyzing a material under controlled conditions including:
- Air pressure
- Electromagnetic radiation
- Microwave radiation
Corrosionpedia explains Vacuum Degassing
During the production process, a product’s metal components can become infused with excess amounts of gases. As a result, unwanted imperfections and side effects can impact the integrity or performance of the metal.
Vacuum degassing processes involve the exposure of molten steel to a low-pressure environment to remove gases (chiefly hydrogen and oxygen). The effectiveness of any vacuum degassing operation depends upon the surface area of liquid metal that is exposed to low pressure. This process is typically performed in a specially designed chamber known as a vacuum degasser.
The reduced pressure inside the vessel or chamber causes the gas to become less soluble and separate from the liquefied material. After the vacuum degassing process is complete, the gas is removed from the vessel, and the pressure is returned to normal.
Vacuum degassing to remove carbon not only reduces imperfections, but also makes metals more ductile, or easily shaped and formed through cold metalworking.
Vacuum degassing is practiced in the steel industry for purposes such as:
- Removing hydrogen
- Improving cleanliness by removing oxygen
- Producing steel with low carbon content ( < 0.03%)
- Producing steels with close chemical composition ranges (including deoxidizers)
- Controlling pouring temperatures, especially for continuous casting operations
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