鋼胚在高溫氧化的環境中，經過加熱、熱軋及後續冷卻過程中，在其表面均會產生銹皮。為了後續的冷軋製程，鋼片必須經過酸洗處理，將表面的銹皮去除。銹皮的厚度、化學組成及組織結構，都會影響酸洗的效率。本研究的對象為三種不同矽含量的矽鋼片 ( 0.51 % ~ 1.91 % ) 和普通的低碳鋼，探討矽含量對銹皮性質的影響，並對其於5 wt % HCl及5 wt % HCl + 10 wt % Fe+2 溶液中的酸洗行為加以解析。利用XRD、SEM及EPMA，對銹皮做微結構的觀察和元素分布分析，以瞭解矽含量對銹皮組成及結構的影響，並探討其與酸洗行為間的關聯性，酸洗試驗包括靜態及動態兩種方法。

　　實驗結果指出，在同一鋼片，其上、下表面的形態有糙粗度之區別，XRD分析結果顯示銹皮含有Fe 2 O 3、及Fe 3 O 4 兩種氧化物。SEM橫截面觀察發現，銹皮的厚度、連續性及均勻性有顯著的差異。另外於矽鋼片基材與銹皮的界面處，存在著層狀或是散布顆粒之含Fe、Al、O、Si生成物，可能為Fe 2 SiO 4、Fe 2 Al 2 O 4 或是其他的矽酸鹽類。在低碳鋼基材的OCP變化曲線中，出現一電位峰，這是因為表面處生成介穩定態的鈍化膜。酸洗測試結果則顯示，隨著矽含量的提高，酸洗時間有增加的趨勢。此外在HCl之酸洗溶液中，Fe+2離子對酸洗的影響並不顯著。

　　Exposing to oxidizing environment, scaling always occurs on the steel surface during heating, hot-rolling and subsequent cooling. The removal of scale by pickling is a common practice before cold rolling. The thickness, chemical composition and microstructure of scale are important factors affecting the pickling efficiency. In this study, the pickling behavior of various hot rolled steels in 5 wt % HCl solution with or without Fe+2 was investigated. Four different steels with various Si content, in the range of 0.01~1.91wt %, was used. The effect of silicon content on the scale characteristics and the subsequent pickling performance was studied. XRD, SEM and EPMA were employed to analyze the microstructure and chemical composition of the scales formed in these steels. The pickling behavior was evaluated by conducting the test either in static or flowing acidic solution.
　
　　The experimental results indicated that the upper and lower surfaces of the steel strips had different roughness. The results of XRD analyses showed the scale consisted of Fe 2 O 3 and Fe 3 O 4 . SEM examination exhibited that the thickness continuity and uniformity of the cross section of the scale varied considerably. It was also found that a continuous thin film or discrete particles containing Fe, Al, O and Si were present in the Fe / scale interface which might be Fe 2 SiO 4 , Fe 2 Al 2 O 4 or other silicates. The open circuit potential (OCP) measurements demonstrated that the exposure of the low silicon content carbon steel in the pickling solution might result in the formation of a meta-stable oxide on the steel surface. The formation of such meta-stable compound was characterized by the existence of a peak potential during OCP measurement. For the hot rolled steels, the experimental results showed the pickling efficiency decreased with increasing Si content in the steel. Furthermore, the presence of Fe+2 in HCl solution had no significant effect on the pickling performance of the steels in this study.

1. V.B. Ginzburg, Steel-Rolling Technology : Theory and Practice, Marcel Dekker, New York, 1989.
2. R. Y. Chen and W. Y. D. Yuen, Oxidation of Metals, Vol. 53, p. 539, 2000.
3. R. Y. Chen and W. Y. D. Yuen, “ A Study of the Scale Structure of Hot-Rolled Steel Strip by Simulated and Cooling ”, Oxidation of Metals, Vol. 56, p. 89, 2001.
4. R. Y. Chen and W. Y. D. Yuen, Oxidation of Metals, Vol. 59, p. 433, 2003.
5. Fukagawa, Hikaru, Okada and Yasuhiro Maehara, “ Mechanism of Red Scale Defect formation in Si-added Hot-rolled Steel Sheets ”, ISIJ International, Vol. 34, No.11, p.906, 1994. .
6. 吳覺宇、陳友忠，“ 鋼鐵氧化銹皮保護性之電化學研究 ”，技術與訓練9卷3期，民國73年3月，pp. 18-39.
7. A Specialty Handbook : Carbon and Alloy Steels, J.R. Davis and Davis & Associate Associates. Eds., ASM International, Materials Park, OH 1996.
8. George Y. Lai, “ High Temperature Corrosion of Engineering Alloy ”, p.113
9. H. Okada, T. Fukagawa, H. Ishirara, A. Okamoto, M. Azuma, and Y. Matsyda,
ISIJ, International, Vol. 35, p. 886, 1995.
10. 康明瑋，“ 矽含量及脫氧劑對生成銹皮性質之影響 ”，國立成功大學研冶及材料科學研究所，碩士論文，1989
11. A. Atkinson, “ A theoretical Analysis of the Oxidation of Fe-Si Alloys ”, Corrosion Science, Vol.22, p. 87, 1982.
12. A. T. Gorton, G. Bitsianes, and T. L . Joseph, Trans. Of AIM Vol.233, p.1519, 1965
13. P. H. David : Wire Technol., 11 / 12, p.15, 1974
14. N. W. Ariano, “ Oxide and Scale Removal Processes in Mineral Acids ”, Finishing and Coating of Metal Surface ( ASM Conf. ), May, 1978, Louisville, Kentucky.
15. H. J. Engell, Z. Physik. Chem., N. F., 7, p.158, 1956.
16. M. J. Pryor and U. R. Evans, J. Chem. Soc., p.3330, 1949
17. K. H. Buob, A. F. Beck and M. Cohen, J. of the Electrochem. Soc., p.74, 1958
18. R. M. Hudson, C. J. Warning, “ Optimum Pickling Practice with Hydrochloric Acid ”, U.S.S.C. Monroevulle, Pa. U.S.A, 1979
19. 魏豊義，“ 中鋼熱軋鋼帶於不同冷卻速率下生成銹皮之性質及酸洗之研究 ”，技術與訓練8卷11期，民國72年11月，pp.10-24.
20. R. M. Hudson, “ Pickling of Hot Rolled Strip : An Overview ”, I & SM, Vol. 18(9)
p.31, 1991.
21. R. Y. Chen and W. Y. D. Yuen, “ A Study of the Scale Structure of Hot-Rolled Steel Strip by Simulated and Cooling ”, Oxidation of Metals, Vol. 56, p. 89, 2001.
22. George Y. Lai, “ High Temperature Corrosion of Engineering Alloy ”, p.113
vol. 34, No.11, p.906, 1994.
23. Omikako Takeda and Takashi Ohnishi and Youichi Mukai, “ Infkuence if silicon Content on the Primary Scales on Si Containing Steels ”, CAMP-ISIJ, Vol.16, p1360, 2003.
24. 張耀南，“ 不同矽鋁含量之熱軋鋼捲酸洗性研究 ”，The Annual Conf. of the Corrosion Engineering Association of R.O.C, p.151, 1993.
25. 鄭勝元，關聖立，蔡文達，“ 水蒸氣對410及316不銹鋼熱處理銹皮性質及酸洗效果之影響 ”，防蝕工程，民國93年12月
26. Lian-Fu Li, Peter Caenen, Mathieu Daerden, David Vaes, Guido Meers, Caroline Dhondt, Jean-Pierre Celis, “ Mechanism of Single and Multiple Step Pickling of 304 Stainless Steel in Acid Electrolytes ”, Corrosion Science, Vol.47, p.1307,
2005.
27. B. Frish, W. R. Thiele, D. Prediger, Archiv. Eisenhuettenwes. Vol.54, p.311, 1983.
28. H. M. McCullough, M. G. Fontana, F. H. Bech, Trans. Am. Soc. Met. Vol.43,
p.404, 1951.
29. A. A. El-Meligi, S. Turgoose, A. A. Ismail, S. H. Sanad, Brit. Corros. J. Vol.35,
p.75, 2003.
30. R. M. Hudson, C. J. Warning,“ Factors Influencing the Pickling Rate of Hot-rolled Low-carbon Steel in Sulfuric and Hydrochloric Acids ”, Metal Finishing, p.21,
June, 1980.