The so-called bright heat treatment includes bright annealing, bright normalizing, bright quenching and bright tempering. In order to prevent oxidation and decarburization of the surface of the stainless steel seamless pipe so that it does not lose its metallic luster, heat treatment should be carried out in a protective atmosphere or vacuum as mentioned above.
The principle of bright heat treatment process
1. Solution treatment: stainless steel is a special steel containing a variety of alloy elements. After cold working, the original uniform austenite structure is destroyed and the hardenability is obvious. In order to return to the original grain structure, the cold-worked austenitic stainless steel seamless pipe is heated to a high-temperature single-phase region and maintained at a constant temperature, so that various alloy components, including impurities, dissolve each other. At the same time, during the cold working process, a large number of dislocated and deformed metal grains began to swell, and finally uniform grains were precipitated out of a stable solid solution through rapid cooling, and returned to the austenite structure.
2. Bright treatment. During the heating and heat preservation process of stainless steel seamless pipe, if air enters the surface, black scale will appear. In order to ensure the brightness of the substrate, the nitrogen and hydrogen decomposed from ammonia are passed through the heat treatment furnace tube or furnace as a protective atmosphere. Nitrogen is a neutral gas, which protects the workpiece from oxidation and decarburization at high temperatures and keeps it bright, while hydrogen not only protects the brightness, but also has a strong reduction effect, making the workpiece brighter and silvery white, and improving the smoothness of the substrate.
Common Defects in Bright Heat Treatment of Stainless Steel Seamless Tubes
1. Insufficient hardness
2. High hardness
3. There are black spots on the surface of the steel pipe, which is not beautiful
4. The surface of the steel pipe is silvery white and rusty
5. The brightness of the first batch of steel pipes is not good
6. Black or white frost appears in batches
The principle of bright heat treatment process
1. Solution treatment: stainless steel is a special steel containing a variety of alloy elements. After cold working, the original uniform austenite structure is destroyed and the hardenability is obvious. In order to return to the original grain structure, the cold-worked austenitic stainless steel seamless pipe is heated to a high-temperature single-phase region and maintained at a constant temperature, so that various alloy components, including impurities, dissolve each other. At the same time, during the cold working process, a large number of dislocated and deformed metal grains began to swell, and finally uniform grains were precipitated out of a stable solid solution through rapid cooling, and returned to the austenite structure.
2. Bright treatment. During the heating and heat preservation process of stainless steel seamless pipe, if air enters the surface, black scale will appear. In order to ensure the brightness of the substrate, the nitrogen and hydrogen decomposed from ammonia are passed through the heat treatment furnace tube or furnace as a protective atmosphere. Nitrogen is a neutral gas, which protects the workpiece from oxidation and decarburization at high temperatures and keeps it bright, while hydrogen not only protects the brightness, but also has a strong reduction effect, making the workpiece brighter and silvery white, and improving the smoothness of the substrate.
Common Defects in Bright Heat Treatment of Stainless Steel Seamless Tubes
1. Insufficient hardness
2. High hardness
3. There are black spots on the surface of the steel pipe, which is not beautiful
4. The surface of the steel pipe is silvery white and rusty
5. The brightness of the first batch of steel pipes is not good
6. Black or white frost appears in batches
