English
中文简体The final heat treatment that tubes undergo in manufacturing is an important factor in their quality and performance. Bright annealing is a high-temperature, controlled atmosphere heat treatment that removes internal stresses, modifies physical and mechanical properties, and creates a fine-grained microstructure. It also enhances corrosion resistance by removing oxide scale from the surface of the metal. This makes it harder for oxygen to enter and attack the steel and prevents the formation of pitting corrosion.
During the bright annealing process, the tubing is heated in a furnace with a protective gas to keep the metal from discoloring on its bright surface. This gas is typically a mixture of hydrogen and nitrogen from dissociated ammonia that has a dew point below -50 degrees Celsius. This allows the tube to be heated to a very high temperature without oxygen exposure, which is required to maintain a bright annealed surface.
This type of annealing is different from traditional open-annealing and pickling processes that allow oxygen to combine with the metal surface, creating an oxide scale that corrodes. In contrast, the bright annealing process keeps the metal surface clean and free of oxide scale. This improves the tube’s overall corrosion resistance.
The tests were conducted in a marine environment chosen for its high levels of salt concentration, ultraviolet radiation and humidity. They tested the corrosion resistance of open-annealed and bright-annealed tube over a twelve month period. The results showed that the bright-annealed tubes exhibited superior corrosion resistance in this environment, compared to the open-annealed and pickled tubing.
In addition to preventing pitting corrosion, the bright annealing process improves the tensile strength and ductility of stainless steel. This is because it reduces internal stress caused by work hardening. It also produces an austenitic structure with a more regular grain size, which improves the material’s elongation and traction properties.
Bright annealing tube is a highly efficient and economical way to produce high-quality stainless steel products. By reducing the cost of abrasive and chemical-based pickling and polishing, it saves time and money in the production process. This translates into lower prices for the end user. They can be configured to meet virtually any line speed, product dimension and material requirement. They are available with a variety of payoffs, straighteners and drives for reel-to-reel offline processing. When choosing a supplier of bright annealed tubes, it is essential to verify that the tube meets your specifications. Only purchase tubing that has been heat treated to the appropriate standards.
