Why do industrial stainless steel pipes need annealing?

  • By:Bonnie Auyeung
  • Date:2023/04/17

Bright annealing solution provided by Hangao technology makes bright annealed tube with smooth inside and outside surface, precision dimensional tolerance, high strength, strong corrosion resistance and so on. How can such a tube be achieved?

Austenitic stainless steel is widely used in a variety of civil, industrial and military applications. They are available in a variety of product forms, such as bars, rods, sheets, sheets, strips, foil, tubing, tubing, fittings, flanges and other forgings.

If the stainless steel is heat treated in an ordinary furnace, the chromium component in austenitic stainless steel will react with oxygen in the air to form a gray oxide layer, called "scale", which should be removed by pickling process.

The bright annealing solution can optimize this process. In order to maintain a good appearance, preserve the original metallic luster and avoid pickling, austenitic stainless steel should be brightened annealed in protection or vacuum to prevent surface discoloration. All grades of austenitic stainless steel can be annealed. The protective atmosphere can be pure hydrogen, dissociated ammonia, or sometimes vacuum. Protective gas prevents surface oxidation of austenitic stainless steel products during annealing.

So bright annealing solution has the following advantages:

1, bright annealing not only reduces the steel pipe hardness, improve the ductility, improve plasticity, but also easy to cut and cold deformation.

2, improve corrosion resistance by eliminating intergranular carbide precipitation, so that the surface appearance is beautiful. Refining grain and uniform steel structure and composition, improve steel properties, but also prepare for heat treatment.

3, eliminate the residual internal stress in steel, prevent deformation and cracking.

4. Oxidation and decarbonization occur during heating and cooling in ordinary annealing, so the heat-treated steel has been processed extra, which increases the loss and cost of metal.

5. obtain no oxidation bright, good corrosion resistance surface. Because bright annealing is heat treatment of strip steel in the protective atmosphere of hydrogen and nitrogen gas mixture, the surface without oxidation is obtained by strictly controlling the protective gas in the furnace. Compared with the surface obtained by ordinary annealing and pickling, because there is no oxidation process, the chromium deficiency phenomenon is reduced on the surface, and its corrosion resistance is better after polishing.

6. bright treatment to maintain the finish of the rolling surface, can no longer be processed and get a bright surface. Due to bright annealing, the surface of the tube retains the original metal luster, has been obtained bright surface, under the general requirements, can be directly used without processing its surface.

7. There is no pollution problem caused by ordinary pickling method. Annealed tube does not need to be pickling or similar treatment, do not use acid, there is no pollution problems caused by pickling.

So how did we get there?

On-Line Fixing & Fusing (Anealing) equipment can heat the stainless steel welded pipeto 1050°C then cool it to the temperature lower than 100 °C under the protection of hydrogen.The heating power supply of the intermediate ferquency induction is the newest DSP+IGBT structure.With DSP digital control system,there are self protection and self diagnostic functions.With small volume,it heats pipes rapidly and efficiently with energy-saving and low-waste features.The especially developed inducer designed according to the features of stainless steel can save 15%-20% energy in contrast of other products of the same class.Using hydrongen as of gas every minute.

To learn more, pleasr click here: Electricity-Powered Stainless Steel Tubing Bright Annealing Furnace




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