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Development of Surface Protection for Cold Rolled Sheet Column
Editor: LI Jianzhong
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  • WANG Yueding, YAN Sen, YUE Zhongxiang, HAO Xijuan, SONG Yifeng, LI Jianzhong
    Materials Protection. 2022, 55(12): 1-6. https://doi.org/10.16577/j.issn.1001-1560.2022.0331
    In order to study the effect of selective oxidation of silicon on phosphating performance of cold-rolled steel plates, phosphating was performed on cold rolled steel plates with different silicon contents. Electrochemical test, X-ray photoelectron spectroscopy, transmission electron microscopy and scanning electron microscopy were used to analyze the corrosion resistance,composition and morphology of the samples before and after grinding. Results showed that the silicon oxide film formed in the annealing process of cold-rolled steel plate was mainly composed of Si, SiC, SiO2 and SixOy. Before grinding, the phosphating performance of the samples with higher silicon contents was obviously worse, and the corrosion resistance of their phosphating films was also poorer. After grinding, the phosphating performance of samples with different silicon contents had no obvious difference. Through an analysis on the surface composition and microstructure of the cold-rolled steel plates, it could be concluded that the silicon oxide film on the surfaces of samples with high silicon contents was not easy to dissolve in the phosphating solution. During the phosphating process, the anode reaction was hindered by the silicon oxide film, and the deposition of phosphate was affected. In general,the selective oxidation of silicon had a significant effect on the phosphating performance of cold-rolled steel plates.
  • GAO Peng, ZHUO Yue, GUO Yanyan, SUN Guodong, SUN Jianliang
    Materials Protection. 2022, 55(12): 7-13. https://doi.org/10.16577/j.issn.1001-1560.2022.0332
    For studying the influence of different rolling processes on the microstructure morphology and internal stress of pipeline steel, the temperature field and stress field of steel plate under different processes were studied by rolling process experiment and thermal mechanical coupling numerical simulation. Subsequently, the microstructure morphology and internal stress of steel plate were tested and analyzed by metallographic microscope and XRD. The results of an actual measurement of the surface temperature of steel plate showed that the error between the simulated value and the measured value was small, and the temperature field calculated by numerical simulation was reasonable,which could be the basis for stress field analysis. After the steel plate was water-cooled for 20 s,the maximum and minimum temperature differences between the steel plate core and corner were 318 ℃and 211 ℃respectively. The maximum and minimum stress difference between the core and corner of the steel plate was 417 MPa and 260 MPa respectively. In addition, the obtained microstructure was composed of bainite,martensite and ferrite. It could be concluded from the results of experiments and numerical analysis that, it was reasonable to control the final rolling temperature at 800~900 ℃and the cooling rate at 20 ~25 ℃/s. Under these process parameters, the phase transformation nucleation rate of the steel plate was high, the internal stress difference was small, and a mixed microstructure comprising of martensite, bainite and ferrite was finally formed.
  • WANG Junyi
    Materials Protection. 2022, 55(12): 14-21. https://doi.org/10.16577/j.issn.1001-1560.2022.0333
    In order to clarify the influence of the surface characteristics of the substrate on the chromium plating layer formed on the surface during the chromium plating process, the surface states of different substrates were characterized by X-ray photoelectron spectroscopy (XPS),X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and electrochemical test.Results showed that lower surface roughness and more peaks provided more active sites for the deposition of chromium-containing compounds on the substrate surface, which promoted the growth of the chromium plating layer. The grain orientation on the substrate surface would affect the growth of chromium-containing compounds, precisely, higher grain orientation complexity would lead to more defects in the chromium plating layer. Besides, larger oxide film thickness on the surface of the substrate would lead to worse chemical activity of the surface and poorer chromium plating layer quality.
  • JIA Ning, LIU Baofa, YUE Zhongxiang, SONG Yifeng, LI Jianzhong
    Materials Protection. 2022, 55(12): 22-26. https://doi.org/10.16577/j.issn.1001-1560.2022.0334
    Tin plate is a kind of low-price and widely used double-side-tinned sheet steel, and only an addition of a fluxing process is needed to achieve a good reflow effect when using methanesulfonate system to produce tin plate. Herein, in order to reduce the consumption of tin resource and improve the quality of tin plate, salicylic acid (SA) solution was used as the fluxing agent before the reflowing of tin plate. The effects of salicylic acid solution concentration on the corrosion resistance of tin plate and the variation of salicylic acid adsorption state on the surface of tin plate were studied and simulated by scanning electron microscope, Tafel curve, X-ray diffraction (XRD) and high resolution confocal microscopic laser Raman instrument. Results showed that the left shift of the C =O bond in salicylic acid made the orientation of tin grains shift to the lower plane (200). When the concentration of salicylic acid solution was 8 mL/L,the morphology and grain orientation of the tin-iron alloy layer on the tin plate were the optimal, and the corrosion resistance of tin plates with low tin contents was the best when fluxed at this concentration.
  • ZHAO Yanliang, SUN Min, LI Yaomin
    Materials Protection. 2022, 55(12): 27-32. https://doi.org/10.16577/j.issn.1001-1560.2022.0335
    Surface adjustment is an important process in the phosphating process before painting, and its effect directly affects the phosphating crystal morphology. In order to clarify the adsorption property of surface conditioning agent for phosphating on the surface of high strength steel,the exsisting state of elements on the surface of high strength steel was analyzed by X-ray photoelectron spectroscopy (XPS),scanning electron microscope (SEM), focused ion beam (FIB) and transmission electron microscope (TEM), and the adsorption properties of oxides on the surface of high strength steel to the surface conditioning agent particles were analyzed by absorption kynetic experiment. Furthermore, a brief phosphating treatment was performed on the surface of the high strength steel after surface adjustment to examine the initial nucleation state of phosphate. Results showed that the oxides with the highest contents on the surface of high strength steel were Fe2O3 and MnO. Compared with Fe2O3, MnO had a stronger adsorption capacity for surface conditioning agent particles, and could adsorb surface conditioning agent particles preferentially in competitive adsorption. Combining the above-mentioned results with the morphology and element distribution of the surface and cross section of the high-strength steel, it could be proved that the MnO on the surface of the high strength steel was the key to the adsorption of surface conditioning agent particles, and the initial deposition of phosphate occurred at the sites with the surface conditioning agent particles.