Microstructure and Corrosion Resistance of Pack Aluminizing Layer on Pipeline Steel X80

Pack aluminizing was performed on pipeline steel X80 at 950℃ for 4 h.The phase composition and microstructure of the aluminizing layer were analyzed by means of XRD and SEM.The microhardness and electrochemical properties of the pipeline steel X80 before and after aluminizing were also tested by microhardness instrument and electrochemial measurement system.The results show that the aluminizing layer of the pipeline steel X80 was mainly composed of FeAl and Fe3Al alloy phase.Except a small amount of holes existing in the depth of 100 μm,the aluminizing layer was dense and continuous with a thickness of about 220 μm.Compared with non-aluminized pipeline steel X80,the microhardness of the steel after aluminizing was obviously higher.Furthermore,the self-corrosion potential and current density decreased.The corrosion morphology was uniform and no obvious local corrosion morphology appeared.