Bright Annealed 201 304 316L 2205 Stainless Steel Tubing Mirror Polishing Stainless Steel Pipe

Bright Annealing Stainless Steel Tube Specifications

Bright Annealed Definition

Bright annealing (BA) refers to stainless steel material is heated in closed furnace in reducing atmosphere of inert gases, common Hydrogen gas, after fast annealing, rapid cooling, stainless steel has a protective layer on the outer surface, no reflect in open air environment, this layer can resist corrosion attack. In general, material surface is more smooth and brighter.

Before Bright Annealing

The surface of the tube must be clean, no other foreign matter, any matter left on the tubing surface can cause damage during the process.

Inserted Gas

Annealing atmosphere should be free from Oxygen, isolating material, creating a vacuum condition. Inserted gas, common dry hydrogen or argon, can obtain bright result.

Annealing Temperature

Annealing temperature should be noticed depending on different stainless grades, commonly Austenitic steels annealing temperature is at least 1040 degree, soak time is not important. high temperature must be required to have brighter appearance. Heating is done as fast as possible, slow heat results in oxidation.

Some Ferritic stainless steels require lower annealing temperature, such as TP439, cannot be effectively bright annealed, Water quenching will cause scale formation.

After bright annealed, it comes to the final steps of sizing and straightening, stainless steel tube surface perform bright appearance, it is unnecessary to pickling for bright annealed tube.

If bright annealing process is not proper to done, tube surface can crack, stained and may lead to easy corrosion.

Purpose And Advantages Of Bright Annealed

• Eliminate work hardening and obtain satisfactory metallographic structure
• Obtain a bright, non-oxidizing surface with good corrosion resistance
• The bright treatment maintains the smoothness of the rolled surface, and the bright surface can be obtained without post-processing
• No pollution problems caused by common pickling methods

Bright Annealed VS Solution Annealing

Bright annealed is processed in a closed furnace, this controlled atmosphere reduces the surface oxidation to a minimum which results in a brighter surface and a much thinner oxide layer. Pickling is not needed after bright annealing since the oxidation is minimal. Since there is no pickling, the surface is much smoother which results in better resistance to pitting corrosion. using protective gas inserted inside.

Bright Annealed products have a slightly higher hardness and an elevated tensile strength compared to Solution Annealed products.

Solution Annealing is standard step for stainless steel material, it is open air annealing, commonly used to soften materials, minimise residual stresses, improve machinability and increase ductility. Some annealing requires only minutes at temperature whilst others can be prolonged soak times with controlled cooling rates from high temperatures, typically between 1010 & 1150ºC.