帘线钢等温和控冷过程氧化铁皮的形成

制备了80级帘线钢盘条在900℃空气等温5、8、12和16min以及900℃等温后分别以4、12和(4+12)℃/s的冷速冷却形成的氧化铁皮。用激光拉曼光谱仪确定了氧化铁皮是由FeO层、Fe3O4层和极少量的Fe2O3层组成。用金相显微镜观测了氧化铁皮的形貌、各层厚度和钢基体的显微组织。结果表明:由于氧化铁皮中产生了CO和CO2气体,900℃空气等温形成的氧化铁皮,除5min的样品外,都出现不同程度的裂缝或孔洞;随等温时间的延长,FeO中不断析出先共析Fe3O4,FeO层的急剧增加导致氧化铁皮总厚度增加。随冷速的提高,FeO层及氧化皮总厚度减少,钢基体中索氏体含量增多。以12℃/s冷却形成的氧化铁皮和基体组织,既有利于机械剥壳,又有利于盘条冷拉拔。

Formation of oxide scale on tire cord steel during isothermal holding and controlled cooling

Samples of 80 grade wire cord rod were heated to 900?? and held in air for 5, 8, 12 and 16min. Other samples were isothermally held at 900?? and then cooled to room temperature at 4,12 and (4+12)??/s. Oxide scale on wire cord rod, determined by Laser Raman Spectroscopy (LRS), are composed of layers of FeO, Fe3O4 and little Fe2O3.The morphologies and thicknesses of three layers of oxide scale as well as the microstructure of base of rod were analyzed by OM. The results indicate that there are cracks or holes in oxide scale formed at 900?? during holding stage except that held for 5min due to CO and CO2 gases generated in oxide scale. The thickness of FeO layer increases quickly with increasing holding time and leads to increase of total thickness of oxide scale. Meanwhile, proeutectoid Fe3O4 precipitates in FeO layer. The thicknesses of FeO layer and total oxide scale are reduced with increasing cooling rate, and the amount of sorbite in base of rod increases. The oxide scale and microstructures in wire rod formed at the cooling rate of 12??/s, are beneficial to mechanical descaling and cold drawing.