含Si低合金热轧带钢除鳞温度的模拟与控制

板坯除鳞残留的氧化铁皮严重影响热轧后带钢的表面质量,而合理的除鳞温度可以有效清除氧化铁皮。以510L板坯为研究对象,建立了三维有限元模型,模拟了有氧化铁皮和无氧化铁皮条件下板坯出炉至除鳞过程的温降,分析了不同出炉温度对除鳞效果的影响,通过调整板坯出炉温度,实现了对除鳞温度的控制。结果表明:板坯在1 180 ℃和1 220 ℃下出炉后的整体冷却趋势相似,在无氧化铁皮条件下,出炉后0~10 s冷却速率约为1 ℃/s,出炉后10~90 s冷却速率约为0.4 ℃/s;在有氧化铁皮条件下,出炉后0~10 s冷却速率约为0.2 ℃/s,出炉后10~90 s冷却速率约为0.08 ℃/s;由于一定厚度的氧化铁皮有利于保持板坯表面温度,因而只要在无氧化皮条件下达到所需除鳞温度(Fe₂SiO₄熔点以上),即可保证整个板坯满足最佳除鳞条件。结合实际生产,考虑除鳞水作用下的瞬时温降影响和板坯输送过程短时间耽搁的情况,得到板坯出炉温度在1 210 ℃时,可保证板坯除鳞温度约为1 190 ℃,高于Fe₂SiO₄的熔点温度1 173 ℃,有效避免了红锈问题的产生。

Simulation and control of descaling temperature of Si-containing low alloy hot rolled strip

The residual oxide scale of the slab after descaling seriously affects the surface quality of the strip after hot rolling, and a reasonable descaling temperature can effectively remove the oxide scale. Taking 510L slab as the research object, a 3D finite element model was established to simulate the temperature drop of the slab from tapping to descaling with and without oxide scale, and the influence of different tapping temperatures on descaling effect was analyzed to control descaling temperature by adjusting the tapping temperature of the slab. The results show that the overall cooling trend of the slab from tapping at 1 180 ℃ and 1 220 ℃ was similar. In the absence of oxide scale, the cooling rate was about 1 ℃/s in 0-10 s from tapping and 0.4 ℃/s in 10-90 s. In the presence of oxide scale, the cooling rate was about 0.2 ℃/s in 0-10 s from tapping, and 0.08 ℃/s in 10-90 s. Because a certain thickness of oxide scale is beneficial to keep the surface temperature of the slab, the entire slab can meet the best descaling conditions as long as the required descaling temperature (above the melting point of Fe₂SiO₄) is reached without oxide scale. Combined with the actual production, considering the influence of the instantaneous temperature drop caused by descaling water and the short-time delay of the slab conveying process, it is obtained that when the tapping temperature of the slab is 1 210 ℃, the descaling temperature is ensured to be about 1 190 ℃. That is higher than the melting point of Fe₂SiO₄ by 1 173 ℃, which effectively avoids the occurrence of red rust.