合金元素與模擬軋延參數對熱軋鋼板氧化銹皮結構之影響

Effects of Alloying Elements and Simulated Rolling Parameters on the Oxide Scales of Hot-rolled Steel Plates

為了瞭解熱軋鋼捲氧化銹皮特性，本研究以中國鋼鐵公司實驗工場現有之熱軋設備，加裝高壓噴水除銹器，模擬熱軋鋼捲生產製程，試驗不同合金元素、高壓噴水角度、軋延溫度、軋延率與軋延方向對碳鋼氧化銹皮組成與厚度之影響。分析技術包含X光繞射、光學顯微金相觀察及掃描式電子顯微鏡（SEM）結合EDS線掃描分析。結果顯示，未添加合金之碳鋼，以15°之角度噴水軋延可得最佳之除銹效果。其氧化銹皮組成以Fe3O4為主，但軋延溫度提高至1000℃以上時，則有Fe3O4及Fe2O3兩種氧化鐵。軋延率及軋延方向，對銹皮組成及厚度均無明顯之影響。含0.32%Cu之鋼材，在內層銹皮有金屬Cu富集，但是含0.41% Ni之鋼材則無此Ni富集之現象。含0.37% Si之鋼材，及同時含0.40% Si和0.48%Cr之鋼材，在銹皮／底材界面均有Si 富集，惟後者並無Cr富集之現象。

In order to understand the oxide-scale characteristics, this study is to set up a hydraulic descaling apparatus in the present pilot-plant hot-rolling equipment of China Steel Corp. to simulate the manufacturing process of hot-rolled steel coils. Effects of different alloying elements, high-pressure hydraulic descaling lead angles, rolling temperatures, reduction ratios, and rolling directions on the structure and thickness of oxide scales have been investigated. The characterization of oxide scales was included X-ray diffraction, optical microscopy, and scanning electron microscopy (SEM) together with EDS line scanning. The results indicated that the optinum lead angle of descaling efficiency of the unalloyed carbon steel is 15°. The oxide scale was mainly composed of Fe3O4, however two oxides, Fe3O4 and Fe2O3, existed if the rolling temperature increased to above 1000℃. The reduction ratio and the rolling direction did not have significant effects on the composition and thickness of the scale of this steel. Metallic Cu was segregated in the internal scale of the steel with 0.32% Cu. However, no Ni segregation was observed in the steel. Segregation of Si was observed at the scale/substrate interface of the steel with 0.37% Si and the one with 0.40% Si and 0.48% Cr. However, no segregation of Cr was observed in the latter steel.