| The oxide scale formed during hot-rolling processing had properties of loose structure and complex composition. It was necessary to pick out the oxide scale of304stainless steel to improve surface quality, otherwise it would be pressed into the subject and cause the surface defects, and the mainly influence during the pickling processing was the concentration of chloride ion and the structure, composition of oxide scale.In this paper, the structure, composition of the oxide scale and passive film after passivation processing formed on the surface of304stainless steel in two different conditions of heating atmosphere (coke oven gas and converter gas) and three concentrations of chloride ion (A、 B、C respectively) was systematacially researched by surface analysis ways such as Metallographic microscope, Scanning electron microscope (SEM), Glow discharge spectrometry (GDS) and X-ray photoelectron spectrometer (XPS).The results showed that the structure, composition of oxide scale formed in coke oven gas and converter gas was similar with density inner layer that combined well with subject and loose outer layer where concentration of chromium was much lower than inner layer. The depth of oxide scale in coke oven gas condition was thicker than that of converter gas obviously and so was the density. The layer of poor chromium formed in depth about1μm and3μm from the surface of subject separately. The ratio of oxide changed into much more lower valence oxide and chromium oxide gradually when close to inner layer. But there was not any other different in composition and structure.Both of depth of the oxide scale and the density inner layer became thinner with the increased of concentration of chloride ion. The subject surface had fewer pit defects and the density inner layer would be cleaned up in the concentration condition of C, although the property of passive film had no obvious correlation with the concentration of chloride ion, the depth and density of the passive film was appropriate. |
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