熱軋鋼捲軋延銹皮與氧化銹皮之研究

A Study of Scale Formation during Hot Rolling and Oxide Scales of As-rolled Steel Coils

本文是在實驗室以850 ~ 1150℃模擬氧化研究熱軋鋼捲軋延溫度與軋入銹皮之關係，並分析實際現場熱軋完軋鋼捲氧化銹皮與內儲致銹性的關係。實驗方法包括氧化與曝露試驗、氧化銹皮分析、鋼材硬度與抗拉強度測試、完軋鋼捲腐蝕電位量測與底材金相觀察。結果顯示氧化溫度愈高，生成銹皮的FeO含量愈少，Fe3O4含量愈多，銹皮硬度愈大，銹皮和底材硬度的比值也更大，較易被軋入底材而造成軋入銹皮。完軋鋼捲若銹皮含較多的孔隙，外界的腐蝕性氣氛較容易經由孔隙進入銹皮內部與底材反應，則易產生點狀銹蝕。

The simulated oxidation behavior between the rolling temperature and the rolled-in-scale of hot-rolled steel coils has been investigated over the temperature range of 850~1150℃. The relationship between the indoor rusting and the oxide scale of as-rolled steel coils has also been investigated. The methods included oxidation and rusting tests, microstructural analyses of oxide scales and the substrate, hardness and tensile testing, and the measurements of corrosion potential of as-rolled steels. The results showed that the higher the temperature, the more amount of Fe3O4, but the less amount of Feo present in the scales. The hardness ratio of the scales to the substrate also increased with increasing temperature, resulting in an easier increase the amount of rolled-in-scales during the rolling process. Concerning the oxide scales of the as-rolled steel coils, the more the pores in the scales, providing the shortcut of the corrosive species in the environments to diffuse through the scale and react with the substrate, the easier the point rusts could form in the scales.