Abstract：The inclusions，microstructures and the content，morphology and distribution of retained austenite in X90 pipeline steel were analyzed by means of metallography，scanning electron microscopy（SEM），electron back scatter diffraction（EBSD），X-ray diffraction（XRD）and magnetic method，respectively.The stability of retained austenite in X90 pipelinesteel wasstudied byanalyzing thechange of retained austenite contentbefore andafter impactandtensile tests.The results showed that the inclusions in X90 pipeline steel were not serious，mainly consisted of D-type spherical oxide inclusions.The microstructure of X90 pipeline steel was mainly lathbainite，as well as a small amount of granular bainite and retained austenite. The retained austenite in X90 pipeline steel was unstable and martensite transformation would occur during impact and tensile tests.
2019, Vol. 37 
