熱軋工廠軋輥高溫氧化性質研究

High Temperature Oxidation Behaviors of Rollers of Hot Strip Mill

為了提高軋延噸數降低工輥更換頻率，並且提升鋼帶表面品質，瞭解熱軋工輥的高溫氧化性質是相當重要的課題。由於工輥於熱軋工廠使用時表面會生成黑膜，其對於軋輥的高溫氧化性質影響效應為何，也令人關切。因此本研究主要針對工輥試片進行高溫氧化性質研究，並提出工輥黑膜生成機構。主要研究結果如下：（1） 750℃含水蒸氣及不含水蒸氣高溫氧化環境4小時之腐蝕速率比較發現，環境濕度上升，高溫氧化速率有明顯增加之趨勢，顯示熱軋工廠的冷卻水殘留，對於工輥的抗氧化能力有不利的影響。（2）雷射共焦顯微鏡量測結果顯示，黑膜表面島狀壟起數量越多、高度越高及破裂越明顯，其粗糙度越大，高溫氧化速率越快。（3）工輥Matrix（麻田散鐵）的氧化速率要高於碳化物，尤其碳化物與Matrix之界面附近的氧化速率會最快。（4）黑膜實際的硬度要遠低於基材，故其主要扮演潤滑作用，來降低軋延磨擦力，減少工輥磨耗，而不是直接抗磨耗。（5）黑膜成長過程可以分解為5個步驟，其詳細成長機構將在本文中討論。

To understand the high temperature oxidation behaviors of rollers of hot strip mill is a very important topic for increasing rolled productivity, decreasing replacement frequency of rollers, and improving strips surface quality. Because black films formed on the surfaces of work rollers in hot strip mill, their effects on the high temperature oxidation property of roller are also deeply concerned. Therefore, the high temperature oxidation behaviors of work rollers and the formation mechanism of black films on the surfaces of rollers were performed in this study. The major results were below: (1) The high temperature oxidation rate at 750 ℃ for 4 hours obviously increased with the increasing humidity no matter water vapor existed or not. This result indicated that the retained water on the rollers was harmful to oxidation resistance. (2) The test result of laser confocal microscope showed that the more the amounts, the height, and the fracture of black film islands were, the faster the high temperature oxidation rate was. (3) The oxidation rate of roller matrix (martensite) was higher than that of carbide, especially on the interface between carbide and matrix. (4) The hardness of black film was significantly deeply lower than that of matrix. The role of black film principally played a lubrication effect to reduce the rolling force and decrease the wear of roller. (5) The growth process could be decomposed into 5 steps. The detailed growth mechanism would be discussed in this paper.