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 cs seamless steel pipes?
Heat treatment of metal materials is divided into overall heat treatment, surface heat treatment and chemical heat treatment. The heat treatment of seamless steel pipes generally adopts the overall heat treatment.
Carbon steel seamless steel pipes (CS seamless pipe) 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 CS seamless pipes mainly include unqualified structural properties of steel pipes, unqualified dimensions, surface cracks, scratches, severe oxidation, decarburization, overheating or overburning, etc.
The first process of heat treatment of CS seamless steel pipe 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 heat treatment of CS seamless pipe 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 CS seamless pipe 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.
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