X80管线钢的高温氧化行为

利用热重法对X80管线钢高温氧化行为进行系统研究，分析不同温度下氧化增重和氧化铁皮形貌演变规律及合金元素在氧化层与钢基体界面处的分布规律.实验结果表明:700~1200℃范围内，X80钢氧化增重曲线呈现抛物线规律.此外，氧化铁皮厚度随温度升高而增加，特别是当温度高于800℃时，由于金属基体存在相变，氧化铁皮厚度急剧增加.高温条件下X80钢氧化铁皮为典型三层结构，外层为极薄的Fe₂O₃，中间层为Fe₃O₄，内层为粗大柱状晶FeO，并在靠近钢基体处形成一层晶粒细小的内氧化层，内氧化层阻碍了铁氧离子的相互扩散，提高了X80管线钢的高温耐蚀性.

High-Temperature Oxidation Behavior of X80 Pipeline Steel

The high-temperature oxidation behavior of X80 pipeline steel was studied systematically by the thermogravimetric analysis. The oxidation weight gain， morphologies of the oxide scale and the distribution of alloying elements at the oxide/substrate interface at different temperatures were analyzed. The results show that in the range of 700~1200℃， the curves of oxidation weight gain of X80 steel follow the parabolic law and the thickness of the oxide scale increases with the temperature， especially when the temperature is higher than 800℃， owing to the phase transformation in the substrate. The oxide scale of X80 steel has a typical three-layer structure at high temperature， consisting of the outer thin Fe₂O₃ layer， the middle Fe₃O₄ layer and the inner FeO layer with the coarse columnar. Also， there is an internal oxidation layer with fine grains formed near the steel substrate. The internal oxidation layer suppresses the interdiffusion of iron and oxygen ions， and improves the high-temperature corrosion resistance of X80 pipeline steel.