| LU Yue,ZHANG Cai-dong,QI Jian-jun,SUN Li,MA Cheng,LIU Yan-li,XIONG Zi-liu.Surface Color and Oxide Formation Rule of Galvanized Hot-formed Steel[J],52(5):208-217 |
| Surface Color and Oxide Formation Rule of Galvanized Hot-formed Steel |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.05.020 |
| KeyWord:hot-formed steel GI coating color difference GDOES TEM oxide roughness |
| Author | Institution |
| LU Yue |
HBIS Material Technology Research Institute, Shijiazhuang , China |
| ZHANG Cai-dong |
HBIS Material Technology Research Institute, Shijiazhuang , China |
| QI Jian-jun |
HBIS Material Technology Research Institute, Shijiazhuang , China |
| SUN Li |
HBIS Material Technology Research Institute, Shijiazhuang , China |
| MA Cheng |
HBIS Material Technology Research Institute, Shijiazhuang , China |
| LIU Yan-li |
HBIS Material Technology Research Institute, Shijiazhuang , China |
| XIONG Zi-liu |
HBIS Material Technology Research Institute, Shijiazhuang , China |
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| Abstract: |
| This paper took the hot-dip galvanized hot-formed steel 22MnB5 as the research object. The morphology and element composition of the surface oxides in hot-dip galvanized hot-formed steel under different heat treatment time was compared. The mechanism of the surface oxides of the hot-dip galvanized steel with the holding time was summarized, to provide a practical reference for subsequent coating and welding production. 22MnB5 galvanized sheet with a thickness of 1.4 mm was used and processed into a sample of 60 mm× 60 mm. Before the test, acetone was used to clean the oil stains and attachments on the surface of the sample. The sample and place was dried in an oven. The SX2-16-13 box-type resistance furnace was used for the heat treatment. The initial heating temperature of the heat treatment was 850 ℃. The sample was taken out and water-cooled immediately. The experiment was carried out under standard atmospheric pressure, the ambient temperature was 25 ℃ and the humidity was 10%. The sample was prepared into a metallographic sample of 10×10 mm with a inlaid cross section, and was then ground and polished. The metallographic sample was corroded with 4% nitric acid alcohol solution for about 15 s. The color difference experiment was carried out on the heat-treated sample and X-Rite MA-T6 multi-angle colorimeter was used for color difference analysis. Based on the samples with better surface quality within 2 minutes of each group temperature, 6 samples of 45as-15~45as110 were measured respectively. The chromatic aberration results under geometric conditions were averaged and the light source viewing angle was D65/10. To measure 1-10 min surface color difference ΔEab, ZEISS Ultra55 field emission scanning electron microscope was used to observe the model with energy spectrum analysis and photography. Combined with the SEM image, the change law of the surface morphology of the coating with the holding time can be summarized. TEM observation and EDS analysis were carried out by FEI Talos F200X. At the same time, in order to determine the molecular formula and valence state of the surface oxide, high-resolution XPS test was carried out. The mechanism of oxides on the surface of galvanized hot-formed steel with holding time was summarized. With the increase of holding time, the color difference ΔE gradually increased. At 945 ℃, the continuity of the coating was damaged and gradually fall off. After being heated at 880 ℃ for 2 min, the surface of the 22MnB5 steel coating remained coherent and dense. There were dispersed square oxide particles and the surface height of the coating did not fluctuate little. At 10 min, a large number of oxide layers continuously covered the surface while oxide aggregation existed. Cracks were initiated at the oxide aggregation position and passed through the oxide, and the oxide level on the surface of the coating was significantly different. The elements of the coating were fully diffused after a long time of holding. The coating was mainly composed of α-Fe(Zn) phase and the overall Zn concentration tended to decrease. The coating surface is composed of ZnO, FeO and Al2O3. ZnO continuously covered the surface and presented a continuous distribution trend, which effectively avoids the volatilization of Zn on the coating surface at high temperature which kept the Zn content within a certain range so that the coating has the effect of cathodic protection. |
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