中碳钢盘条的高温氧化行为研究

Study on high temperature oxidation behavior of medium carbon steel wire rod

针对中碳钢盘条的高温氧化问题,利用热重分析仪对45钢和40Cr钢盘条的高温氧化行为进行了试验研究;采用场发射电子探针表征了氧化铁皮厚度及截面微观形貌,对氧化铁皮形貌演变规律以及合金元素在氧化铁皮与基体界面处的分布规律进行了研究分析。结果表明:45钢和40Cr钢盘条的氧化增重曲线在1050~1250℃范围内遵循抛物线规律,当氧化条件相同时,相比于常规低碳钢,其氧化激活能较高,抗氧化性能更好;氧化铁皮呈典型的3层结构,从外到里分别为Fe_(2)O_(3)、Fe_(3)O_(4)及FeO,并且在氧化铁皮与基体界面处存在合金元素富集层;45钢盘条在高温氧化时,Cr元素分布不明显,Si元素在氧化铁皮与基体界面处有少量富集,Mn元素在氧化铁皮中均匀分布;40Cr钢盘条在氧化铁皮与基体界面处不仅有富Si层,还明显存在一层均匀完整的富Cr层,由于合金元素富集层阻碍了Fe^(2+)向外扩散,提高了盘条的高温抗氧化性能。

In view of high temperature oxidation problem of medium carbon steel wire rod,the high temperature oxidation behaviors of 45 steel and 40 Cr steel wire rod were analyzed by thermogravimetric analyzer.At the same time,the thickness and cross-sectional morphologles of the oxide scale were characterized by field emission electron probe.The morphology evolution of the oxide scale were systematically studied,and the distribution of alloying elements at the interface between the oxide scale and the substrate were also analyzed.The results show that the oxidation weight gain curves of 45 steel and 40 Cr steel wire rods follow the parabolic law in the range of 1050-1250℃.When the oxidation conditions are the same,compared with the conventional low carbon steel,the oxidation activation energy of the tested steels are higher and the oxidation resistance are better.The oxide scale shows a typical three-layer structure,which is Fe_(2)O_(3),Fe_(3)O_(4) and FeO from outside to inside,and there is a alloying element enrichment layer at the interface between the oxide scale and the substrate.When the 45 steel wire rod is oxidized at high temperature,the distribution of Cr element is not obvious,Si element is slightly enriched at the interface between the oxide scale and the substrate,and Mn element is evenly distributed in the oxide scale.The 40 Cr steel wire rod not only has a Si-rich layer at the interface between the oxide scale and the substrate,but also a uniform and complete Cr-rich layer.Since the alloy element enrichment layer hinders the outward diffusion of Fe^(2+),the high temperature oxidation resistance of wire rod are improved.