Bright annealing and aerobic annealing of stainless steel are two distinct heat treatment processes, with the main differences lying in the treatment environment, surface effect, performance impact and application scenarios.
The Environment for Processing
Bright Annealing
- Inert gas protection: Carried out in an oxygen-free environment (such as nitrogen, hydrogen or argon) to prevent metals from coming into contact with oxygen.
- Vacuum environment: In some cases, a vacuum furnace is used.
- Objective: To prevent oxidation and maintain a bright surface.
Aerobic Annealing
- Air environment: Heat directly in an oxygen-containing atmosphere (such as air).
- Objective: To allow controlled oxidation to occur on the surface and form an oxide layer
The Influence of Performance
- Corrosion resistance: Better, as there are no oxidation defects (such as intergranular oxidation).
- Mechanical properties: Precise control to prevent material embrittlement.
- Carbon control: Avoid carburization or decarburization, suitable for low-carbon stainless steel (such as 304, 316)
Aerobic annealing
- Oxidation risk: It may cause intergranular oxidation or chromium loss (especially in the sensitization temperature range), reducing corrosion resistance.
- Subsequent treatment: Acid washing is required to remove the oxide scale, which may increase the cost.
The cost and equipment
Bright annealing
- The equipment is complex (requiring gas protection or vacuum systems) and has a relatively high cost.
Aerobic annealing
- The equipment is simple (ordinary annealing furnace) and has a low cost, but subsequent processing may increase the total cost.
Typical Application
Bright annealing
- Medical devices, food industry equipment, electronic products, high-end decorative materials.
- General industrial components and structural parts (for scenarios that require subsequent processing or spraying)
Conclusion
Which process to choose depends on the product requirements: if high surface quality or corrosion resistance is needed, bright annealing is preferred. If cost is sensitive and subsequent treatment is acceptable, aerobic annealing is more economical.