OCTG (Oil Country Tubular Goods) casing and tubing are widely used in the steel industry. However, these materials often face the issue of decarburization. To prevent decarburization in OCTG casing and tubing, two primary methods can be employed:
Nitrogen Protection:
This straightforward method involves using nitrogen to maintain pressure inside the furnace. Workers introduce neutral nitrogen into the furnace, which prevents the outside air from decomposing into oxygen and water vapor that could cause decarburization. Additionally, nitrogen helps disperse existing oxidizing gases within the furnace. By eliminating reactive mediums from the carbon surface, decarburization is prevented, significantly reducing its occurrence.
Controlling Furnace Gas Composition:
This method involves balancing the levels of carbon dioxide within the furnace according to the specific requirements of the OCTG casing and tubing workpieces. Research indicates that if the balance in the furnace atmosphere is higher than the carbon dioxide content, decarburization and oxidation will not occur. If the carbon dioxide level is equal to the balance point, a neutral atmosphere is achieved, preventing decarburization and oxidation. However, if the oxidizing gas content exceeds the balance point, decarburization is likely to happen. To avoid decarburization, it is essential to calculate the balance point based on the internal temperature and carbon content of the workpiece and then control the oxidizing gas levels within the furnace accordingly.
