The silicon steel was cold rolled by using an oil-in-water emulsion for lubricating its surfaces. Oil in water (O/W) emulsion is a lubricant composed of oil in the form of droplets suspended in water. This paper mainly researched on the new emulsion which was prepared by changing the compound proportion between antioxidant 2, 6-Di-tert-butyl-p-cresol (T501) and antirust agent petroleum sodium sulfonate (T702). The corrosion behavior of the emulsion was investigated by weight loss and electrochemical methods. The mechanisms for inhibition of corrosion synergism between T501 and T702 in base oil were studied. The results show that the antirust agent (T702) can effectively forming a layer of adsorption film on the rolled strip surface and this adsorption film can segregate strip surface from air and water. The antioxidant (T501) can capture oxygenic free radical (•OH, RO•, ROO•) and carbon free radical and reduces the trend which emulsion occur oxidation reaction under high temperature and high pressure. The antioxidant plays a minor role in inhibition of corrosion synergism. The results show that the best compound proportion content is 4% antioxidant (T501) and 8% antirust agent (T702), which can effectively increase the anticorrosion effect of emulsion. Meanwhile, the self-corrosion potential and self-corrosion current of the sample is minimal and the self-corrosion current is 1.0226×10-7A/cm2.

For the cold-rolled silicon steel strip lubricated with emulsion, the typical oil spot defects always can be found on the surface of rolled strip. The oil spot are parallel to the rolling direction. In the present study the micro-structure of oil spot defects was investigated by several surface analysis techniques, including LEXT ols4000 laser scanning confocal microscope, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS). The chemical compositions of the oil spot defects were analyzed by EDS. The results showed that the surface quality of the rolled non-oriented silicon steel was affected strongly by emulsion stability. The emulsion stability decreased with the increasing content of CL-. When the particle size of emulsion was larger, the lubricity of the emulsion deteriorated. Furthermore, there were some emulsions which contain miscella on the strip steel surface. The emulsions existed in the confined areas where the plate shape defects formed. The majority of its water was evaporated with the increasing of temperature and time. The oxides and residual emulsions could be found on the surface strip steel, which originated from the oxidation reaction between vapors and silicon steel surface. Eventually, the reaction produced some oxides (Fe3O4, FeO, Fe2O3, SiO2, CoCr2O4, NiCr2O4, Fe-Cr) and other by-products. In addition, the emulsion spots area were easier to suffer corrosion than the normal area under the same conditions.