Influence of Coiling Temperature on Microstructure and Properties of X80 Pipeline Steel

X80 pipeline steel plate was prepared by controlled rolling and controlled cooling method using a  450 mm laboratory rolling mill.The influence of coiling temperature on the microstructure and mechanical properties of the steel was investigated by means of optical microscope,TEM and mechanical property tester.The results show that when the coiling temperature increased from 463 ℃ to 597 ℃,the content of acicular ferrile(AF) in X80 pipeline steel increased,and the M-A island became finer and well-proportioned.When the coiling temperature was 597 ℃,the yield strength and tensile strength of X80 pipeline steel could be 650 MPa and 790 MPa respectively,and the elongation was about 30%.