Cracking reason of 20G seamless steel pipe

A 20G seamless steel pipe cracked after a period of service. The cracking reasons were analyzed by means of chemical composition analysis, hardness test, metallographic examination,electron microscope scanning and energy spectrum analysis. The results show that serious decarburization occured on the inner surface of the 20G seamless steel tube, and the decarburization reason was related to the piercing and continuous rolling process.