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采用热模拟试验机研究了不同温度和等温时间下汽车大梁钢表面形成的FeO层的等温转变行为,结合实验结果绘制出510L,610L钢的氧化铁皮的等温转变曲线。结果表明,两个钢种FeO层的等温转变均遵循“C”曲线规律,510L钢的FeO层发生先共析转变的“鼻温”范围为450~550℃,而共析转变的“鼻温”范围为350~450℃;610L钢FeO层发生先共析转变和共析转变的“鼻温”范围分别为350~400℃和350~450℃,610L钢的共析和先共析转变比510L的更加困难。随Fe3O4含量减少,脱落形式由粉末状脱落向片状脱落过渡。结合研究结果得出最优热轧氧化铁皮结构为以Fe3O4为主,其含量控制在60%左右,少量FeO在Fe3O4中成均匀的岛状分布,并确定了控制氧化铁皮结构的工艺,即精轧开轧温度为1000~1030℃,终轧温度为870~920℃,卷取温度为570~630℃。
The isothermal transformation behavior of the FeO layer formed on the surface of automobile girder steel under different temperature and isothermal time was studied by means of thermal simulator. The isothermal transformation curves of 510L and 610L steel oxide scale were drawn based on the experimental results. The results show that the isothermal transformation of two FeO layers follow the curve of “C ” curve. The “nose temperature” of the FeO layer of 510L steel ranges from 450 ℃ to 550 ℃, while the eutectoid transformation Of the “nose temperature” range of 350 ~ 450 ℃; 610L steel FeO layer proeutectoid transformation and eutectoid transformation of the “nose temperature” range of 350 ~ 400 ℃ and 350 ~ 450 ℃, 610L steel It is more difficult to co-analyze and first analyze the transformation than the 510L. With the Fe3O4 content decreased, shedding form from the powder off to flake transition off. According to the results of the study, the optimum hot-rolled scale structure is mainly Fe3O4, its content is controlled at about 60%, a small amount of FeO is uniformly distributed in Fe3O4, and the process of controlling the scale structure is determined Rolling temperature is 1000 ~ 1030 ℃, finishing temperature is 870 ~ 920 ℃, coiling temperature is 570 ~ 630 ℃.