Stainless Steel Fittings Heat Treatment

Manufacturer of stainless steel pipe fittings not only consider cost of pipe fittings, but consider corrosion prevention and product quality. Therefore, stainless steel pipe will take the solid solution in the manufacturing, because it enhance the safety of pipe fittings. The Stainless Steel Treatment is very important for the quality and safety of the pipe. There are small number of manufacturers in order to save costs. It will bring permanent troubles in future that changes solid solution to polished sand blasting for the purpose of covering defects.

The solution treatment is the stainless steel heated to 950~1150℃, then preservation the temperature for a certain time. This process makes carbide and various alloying elements evenly dissolved,  Austenitic stainless steel are soften.

Stainless Steel Heat Treatment Effect 

After forming and welding of the stainless steel pipe, the structure, magnetism and physical properties of the metal have changed. The solution process can restore the corrosion resistance after processing, and obtain the hardness of stainless steel to ensure the best performance. After the solution treatment of stainless steel pipe fittings, has a good role in improving:

1. Make pipe fittings more convenient and safe in the installation. It eliminates modification phenomenon of Stainless Steel Pipe Fittings, so that the hardness reduced to 220HV below, and improves plasticity and toughness as well.

2. Restoring the stress and intergranular change of stainless steel pipe fittings in the process, reduce stainless steel intergranular corrosion and stress corrosion, enhance corrosion resistance.

3. Removing magnetic, stable austenite organization of stainless steel due to processing.

4. Restoring the surface natural brightness of the stainless steel material (natural bright and polished light is different).

Characteristics of Stainless Steel Pipe Fittings Solid Solution

Stainless steel is a special steel, since nickel, chromium and other alloying elements exist. So it has different characteristics with ordinary steel heat treatment.

1. The thermal conductivity of stainless steel is low, so heating process at low temperature should be slow. At room temperature, stainless steel  only has 27% of carbon, and with the increases of heating temperature, the thermal conductivity characteristics and difference decreases gradually.

2. Austenitic stainless steel is get to 1100 ℃ by solution heating, can inhibit the production of carbide, and then quickly cooled to room temperature, so that carbon reached over saturation, can greatly improve corrosion resistance of stainless steel.

3. Pipe fittings are using (hydrogen) gas protection in the solution process, to avoid stainless steel surface viscous iron oxide production, Restoring stainless steel surface,and improving the appearance of the reputation.

Three Elements for Solid Solution Stainless Steel Pipe Fittings

The advantages and disadvantages of solution process have a great influence on the corrosion resistance and the appearance brightness of stainless steel, and it plays a decisive role in the processing performance. Therefore, the heat treatment has play a important position s in the production of stainless steel pipe fittings

1.Solution temperature. According to the characteristics of stainless steel chemical composition, solution temperature of 950-1150 degrees to achieve softening effect, so that the hardness of stainless steel reduced to 220HV, to meet the quality requirements of pipe installation. If the temperature control is unreasonable, it is easy to appear various quality defects.

2. Solution time. The residual ferrite content of austenitic stainless steels decreases with heating time increasing in the heating process. Therefore, the solution treatment should at 1050 ℃. So that the carbon reaches saturation, improve corrosion resistance. And then quickly cooled in the air to achieve the solution effect.

3. The heating process of stainless steel at low temperature should be slow. If the heating speed is too fast to produce deformation,so should be controlled heating speed, and pay attention to heat preservation time. such as 316L in 1100 ℃, residual ferrite content will continue to be reduced if holding time long.

The solution of stainless steel pipe fittings should be heated–insulation–time cooling process, it will take about 40 minutes.