连铸结晶器内大方坯的热力耦合分析

Thermomechanical Model of Heat Transfer in Bloom Casting Mold

针对攀钢大方坯连铸机投产初期铸坯表面角部纵裂缺陷,建立了大方坯连铸结晶器内铜板与铸坯间的热力耦合模型,应用模型分析了大方坯连铸结晶器内的传热过程和坯壳的应力分布。在传热模型中,以稳态模型分析结晶器的传热过程,以瞬态模型分析铸坯的传热过程;在力学模型中,考虑铸坯和结晶器的接触边界以处理结晶器角部的气隙,以热弹塑性模型分析铸坯的变形和应力场。2种结构的连铸结晶器中大方坯温度场和应力场计算结果表明,结晶器倒角从25 mm×45°变为12 mm×45°时,可改善铸坯角部的传热条件,降低凝固坯壳角部温度,增加凝固坯壳厚度,有利于减轻和防止铸坯角部裂纹。

The longitudinal corner surface cracks were occurred at the initial stage of operation of continuous bloom caster at Pangang. Therefore, a thermomechanical model was developed to analyze the heat transfer and the stress distribution of strand in the mold. The heat transfer was analyzed with the steady model and the transient model, respectively. The contact of the mold and strand was taken into account in the mechanical model to treat the air gap formation at the mold corner, and the strain as well as stress of strand were analyzed with thermal elasto-plastic model. The calculated results of the temperature of and stress distribution in the strand cast with two different molds show that the corner configuration has a great effect on heat transfer near the corners. When the corner configuration is optimized from 25 mm×45° to 12 mm× 45°, the strand temperature becomes lower and the solidified shell thickness becomes thicker, which will reduce the cracking tendency near the corners.