HRB400螺纹钢的高温氧化行为及动力学

为了优化HRB400螺纹钢氧化皮结构,以提高耐蚀性能,采用热重法研究了试验钢空气条件下在800、850、900、950、1000和1050℃温度下的氧化行为,建立了氧化动力学模型,计算出试验钢的氧化激活能,借助扫描电镜(SEM)分析和确定氧化皮结构和组成.结合螺纹钢的实际生产情况讨论了螺纹钢氧化皮形成规律,建立了螺纹钢...

High temperature oxidation behavior and kinetics of HRB400 rebar

In order to optimize the oxide layer structure of HRB400 rebar to improve corrosion resistance, the oxidation behavior of test steel under air condition at temperatures of 800, 850, 900, 950, 1 000 and 1050 ℃ was investigated using the thermogravimetric method. An oxidation kinetic model was developed, the oxidation activation energy of test steel was calculated, and the structure and composition of oxide layer was analyzed and determined by scanning electron microscopy (SEM). The oxidation layer formation law was discussed in relation with the actual production of rebar and an oxidation skin growth model was established. The results showed that the oxidation of test steel had a fast oxidation phase with a linear oxidation kinetic curve in the early stages and a slow oxidation phase with a parabolic oxidation kinetic curve in the middle and late stages, and the time required to change from linear to parabolic increased with the temperature increasing. The oxidation activation energy of test steel was 208.4 kJ/mol which was calculated by Origin fitting. The best macroscopic condition of test steel oxide skin surface appeared at an oxidation temperature of 900 ℃, and varying degrees of flaking and damage to the test steel oxide skin at all other oxidation temperatures. At the oxidation temperatures of 850 and 900 ℃, only dark grey outer layer of Fe₃O₄ and light grey inner layer of FeO were observed in the test steel oxide due to the low oxidation temperature which could not break through the energy barrier for Fe₂O₃ production. The oxide skin of test steel at oxidation temperatures of 950, 1 000 and 1 050 ℃ consisted of a three-layer structure of Fe₂O₃, Fe₃O₄ and FeO. As the oxide skin undergone pre-eutectoid reaction (precipitation of Fe₃O₄ from FeO) and eutectoid reaction (transformation of FeO into Fe₃O₄ + Fe) during cooling, a complex oxide skin structure was resulted in.