According to different conditions, the metal material is heated to a suitable temperature and kept warm, and then cooled in different ways to change the metallographic structure of the metal material and obtain the required structural properties. This process is usually called metal material heat treatment. What three processes are included in the heat treatment of carbon steel tubes?

Heat treatment of metal materials is divided into overall heat treatment, surface heat treatment and chemical heat treatment. The heat treatment of carbon seamless steel tubes generally adopts the overall heat treatment.

Steel pipes need to go through basic processes such as heating, heat preservation and cooling during heat treatment. In these processes, steel pipes may have quality defects. The heat treatment defects of steel pipes mainly include unqualified structure and performance of steel pipes, unqualified dimensions, surface cracks, scratches, severe oxidation, decarburization, overheating or overburning, etc.

The first process of carbon steel tube heat treatment is heating. There are two different heating temperatures: one is heating below the critical point Ac1 or Ac3; the other is heating above the critical point Ac1 or Ac3. Under these two heating temperatures, the structural transformation of the steel pipe is completely different. The heating below the critical point Ac1 or AC3 is mainly to stabilize the structure of the steel and eliminate the internal stress of the steel pipe; the heating above Ac1 or Ac3 is to austenitize the steel.

The second process of carbon steel tube heat treatment is heat preservation. Its purpose is to uniform the heating temperature of the steel pipe to obtain a reasonable heating structure.

The third process of carbon steel tube heat treatment is cooling. The cooling process is the key process of steel pipe heat treatment, which determines the metallographic structure and mechanical properties of the steel pipe after cooling. In actual production, there are various cooling methods for steel pipes. Commonly used cooling methods include furnace cooling, air cooling, oil cooling, polymer cooling, water cooling, etc.