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 seamless tubes?
Heat treatment of metal materials is divided into overall heat treatment, surface heat treatment and chemical heat treatment. The heat treatment of seamless steel tubes generally adopts the overall heat treatment.
Carbon steel seamless tubes need to undergo basic processes such as heating, heat preservation and cooling during heat treatment. In these processes, defects may occur in steel pipes. The heat treatment defects of seamless steel pipes mainly include unqualified structural properties of steel tubes, unqualified dimensions, surface cracks, scratches, severe oxidation, decarburization, overheating or overburning, etc.
The main three processes of heat treatment of seamless steel tube:
The first process of heat treatment of carbon steel seamless steel tube 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 tube; the heating above Ac1 or Ac3 is to austenitize the steel.
The second process of heat treatment of carbon steel seamless tube 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 heat treatment of carbon steel seamless tube 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 tube after cooling. In actual production, there are various cooling methods for steel tubes. Commonly used cooling methods include furnace cooling, air cooling, oil cooling, polymer cooling, water cooling, etc.