高碳耐磨球钢大方坯凝固及坯壳生长规律研究

Solidification and Shell Growth Regularity of High Carbon Wear-resistant Ball Steel in Bloom Continuous Casting

基于ANSYS软件建立了310mm×360mm断面大方坯连铸过程二维凝固传热数学模型,通过窄面射钉试验及铸坯表面测温对模型的准确性进行了验证,模拟了不同碳含量的高碳耐磨球钢大方坯宽面和窄面凝固坯壳的生长。结果表明模型能精确地获得不同工况下任意位置凝固坯壳的厚度分布、凝固终点位置及铸坯中心固相率;发现不同碳含量的高碳耐磨球钢具有相同的凝固规律:结晶器弯月面至二冷区出口,相应的铸坯柱状晶区凝固坯壳厚度与凝固时间的平方根呈线性关系,符合平方根定律,并对平方根定律进行了修正,修正项与过热度有关;二冷区出口至凝固终点,相应的铸坯等轴晶区凝固坯壳厚度与凝固时间的平方根呈非线性关系,不再符合平方根定律。

A two-dimensional mathematical model of solidification and heat transfer for a bloom with the cross section of 310mm by 360mm was established with ANSYS software, which was verified by nail-shooting experi- mentsin the narrow side of the bloom and surface temperature testing. Solidified shell growth law of high carbon wear- resistant ball steel with different carbon content in both of wide and narrow side for the bloom was simulated based on the model. The results indicated that the solidified shell thickness distribution in both of narrow and wide side of the bloom at any fixed location along the casting direction, the position of the solidification end Point and the solid frac- tion in the core of the solidified strand could be accurately obtained by using this model; In addition, it was found that high carbon steel with different carbon content obeyed the same law of solidification： from the mold meniscus to the secondary cooling zone export, solidified shell thickness in the center of wide and narrow side and the square root of solidification time showed a linear relationship, which fit a solidification square root law. The law was corrected,andthe correction term was relevant to the superheat. However, the relationship between solidified shell thickness in the center of wide and narrow side and the square root of solidification in the columnar crystal zone was non-linear, which was not fit for the solidification square root law.