加熱條件對含矽鋼高溫銹皮黏附性之影響

Effects of Heating Conditions on High Temperature Scale Adherence of a Siliconcontaining Steel

本文以示差掃描儀（DSC）量測含0.81% Si鋼在高溫生成之矽酸鐵的熔融溫度，並探討此鋼材在加熱爐不同溫度及氣氛對生成銹皮之黏附性的影響，氧化氣氛包括實驗室模擬與現場實際氣氛，黏附性以氧化出爐後水淬量測殘留銹皮之方式評估。結果顯示在1179℃以上，因生成之矽酸鐵開始熔融，銹皮對底材之黏附性大幅提昇。增加氧化性氣氛（H2O、CO2）含量，因矽酸鐵在銹層內分佈之區域增加，使銹皮黏附性微量增加。比較現場與實驗室之結果顯示，現場銹皮黏附性比實驗室小，應是其氧化出爐後水淬前冷卻速率比實驗室慢，使水淬熱應力較大的緣故。

A differential-scanning-calorimetry (DSC) technique was employed to measure the melting point of fayalite formed on a steel containing 0.81% Si at elevated temperatures. Effects of heating temperature and atmosphere in the laboratory and actual mill of the heating furnace on the high temperature scale adherence were investigated. The evaluation of adherence was based on the amounts of the residual scale after the oxidation followed by water quench. The results showed that the scale adherence increased significantly above 1179 ℃ when the fayalite started to melt. Increase of contents of oxidizing atmospheres (H2O, CO2) slightly enhanced the scale adherence due to the increase of cross-sectional distribution of fayalite. It was found that the scale adherence in the mill was smaller than that in the laboratory, because of the slower cooling rate and larger thermal stress in the mill.