Steel tubes made of single metal and without seams on their surfaces are called seamless steel tubes. Seamless steel pipes are mainly used for petroleum geological drilling pipes, Petrochemical cracking pipes, boiler pipes, bearing pipes, automobiles, tractors, aviation high-precision structural steel pipes.


The cold treatment method of seamless steel tube may affect the performance of seamless steel tube, so some preventive measures should be taken in the cold treatment of seamless steel tube. The precautionary measures for cold treatment of seamless steel tubes will be introduced in detail in the following edition:
(1) The seamless steel pipe is put into boiling water for 30-60 minutes. After quenching, the internal stress of quenching can be eliminated by 15%-25%, and the retained austenite can be stabilized. Then, the conventional cooling treatment C is carried out at -60 degrees. The lower the temperature is, the more retained austenite transforms into martensite, but it is impossible to complete the transformation. Experiments show that about 2% - 5% of residual austenite is retained, and a small amount of residual austenite must be retained in compaction to alleviate stress and play a buffer role. Because the retained austenite is soft and tough, it can partly absorb the rapid expansion energy of martensite and reduce the transformation stress.


(2) After the cold treatment is completed, the seamless steel tube is taken out and heated in hot water to eliminate 40% - 60% of the cold treatment stress. When heated to room temperature, tempering should be carried out in time to further eliminate cold treatment stress, avoid cold crack formation and obtain stable structure and properties. Ensure that seamless steel tube products do not deform during storage and use.