Stainless steel pipe fittings production enterprises, to take into account the cost of pipe production, but more importantly, to prevent corrosion and improve product quality factors, therefore, stainless steel pipe fittings production process to take solid solution process, enhance the safety of pipe fittings is very necessary, heat treatment process plays a vital role in the quality and safety of pipe fittings. It is understood that there are a few enterprises in the production of pipe fittings to save costs, did not take solid solution treatment, only with polishing sandblasting and other methods of treatment, covering up the defects and deficiencies of the pipe fittings, which will bring permanent hidden dangers to the use of pipe fittings.
Austenitic stainless steel to soften by heat treatment, stainless steel heated to about 950 ~ 1150 ℃, holding a certain amount of time, so that carbides and various alloying elements uniformly dissolved in austenite, called solution treatment.The role of stainless steel pipe fittings heat treatment
Stainless steel pipe fittings after forming, welding and other process processing, the metal molecular structure, magnetic and physical properties have changed. Through the atmosphere to protect the solution process can restore the corrosion resistance affected after processing, while getting the stainless steel hardness needed to ensure the best use of stainless steel performance. After the solid solution treatment of stainless steel pipe fittings, has a good role in improving.
1, eliminate the modification phenomenon of stainless steel pipe fittings in the processing process, so that the hardness of stainless steel is restored to below 220HV, improve the plasticity and toughness of stainless steel, so that the fittings are more convenient and safe in the installation.
2, restore the stress and intergranular changes in the production process of stainless steel pipe fittings, reduce stainless steel intergranular corrosion and stress corrosion, and enhance corrosion prevention ability.
3, remove the magnetic properties of stainless steel due to the processing process, and stabilize the austenite organization.
4, restore the natural brightness of the surface of stainless steel materials (natural brightness is different from the brightness of polishing).The characteristics of stainless steel pipe fittings solid solution
Stainless steel is a special type of steel, due to the presence of nickel, chromium and other alloying elements, its heat treatment and ordinary steel heat treatment has different characteristics:.
1, the thermal conductivity of stainless steel is low, the thermal conductivity at room temperature is only 27% of carbon steel, and with the increase in heating temperature, the thermal conductivity characteristics of stainless steel, the difference is gradually reduced. Therefore, stainless steel in low-temperature heating, the heating process should be carried out slowly.
2, austenitic stainless steel by solid solution heating to about 1100 ℃, can inhibit the generation of carbide, and then quickly cooled to room temperature, so that the carbon reaches a supersaturated state, can significantly improve the corrosion resistance of stainless steel.
3, pipe fittings in solid solution process using (hydrogen) gas protection, to avoid the generation of sticky iron oxide on the surface of stainless steel, restore the brightness of the stainless steel surface, improve the appearance of the reputation.Stainless steel pipe fittings solid solution of the 3 elements
The advantages and disadvantages of the solid solution process of stainless steel pipe fittings have a great impact on the corrosion resistance and brightness of the appearance of stainless steel, and the processing performance of stainless steel, plays a decisive role. Therefore, the heat treatment process of stainless steel, in the production of stainless steel pipe fittings in a very important position.
1, the solid solution temperature. According to the characteristics of the chemical composition of stainless steel, the solid solution temperature of stainless steel to 950-1150 degrees Celsius, in order to achieve the softening effect, so that the stainless steel hardness reduction to 220HV or less, to meet the quality requirements of the pipeline installation card pressure. If the temperature control is not reasonable, it is easy to have various quality defects.
2、Solidification time. Austenitic stainless steel in the heating process, the residual ferrite content of the steel decreases with the extension of the heating time. Therefore, the solid solution treatment of stainless steel fittings should be controlled at about 1050 ℃, so that the carbon reaches a saturated state to improve corrosion resistance. And then quickly cooled in air to achieve the solid solution effect.
3, solid solution speed and insulation. The thermal conductivity of stainless steel is low, the thermal conductivity at room temperature is only 27% of carbon steel, therefore, stainless steel in low-temperature heating warming process should be carried out slowly. If the heating speed is too fast, it is easy to produce deformation, in solid solution should control the speed of stainless steel heating, and pay attention to the insulation time. Such as 316L steel at about 1100 ℃, holding time is long, the content of residual ferrite will continue to reduce.
We are in the solid solution production, stainless steel pipe fittings solid solution to go through the process of heating - holding - time cooling, the whole process takes about 40 minutes.