摘要
Due to containing alloy elements of chromium and nickel, 30CrNi3 steel usually has some difficulty to be phosphated.In present paper, the growth process of the phosphate coating on 30CrNi3 alloy steel fabricated by a high temperature manganese phosphating was investigated.The microstructure, surface morphology, composition and corrosion resistance of the phosphate coatings were analyzed by XRD, SEM, EDS and electrochemical polarization method, respectively, and the time dependence of open circuit potential (OCP) and coating weight were measured.It is found that it takes 1 minutes for 30CrNi3 alloy steel to form a complete phosphate film, and the phosphate coating is mainly composed of (Mn,Fe)5H2(PO4)4·4H2O and consists of a lot of close packed lump crystallites.The electrochemical polarization measurement shows that the corrosion potentials of the phosphated steel shifted positively about 380 mV than the bare steel, indicating the phosphating can improve the corrosion resistance of the 30CrNi3 alloy steel.