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为控制油井管用连铸圆坯的质量,基于薄片移动法建立了连铸圆坯凝固传热数学模型,并应用Procast软件的CA-FE模块对37Mn5钢150mm圆坯凝固组织进行了模拟。中心等轴晶率模拟结果与工业试验检测结果相一致,据此,建立了柱状晶-等轴晶转变判据。基于此判据的中心等轴晶率预测结果表明,降低过热度、提高拉速和降低二冷零段冷却水分配比均能够降低固液混合区的温度梯度,扩大过冷区范围,有利于晶体的形核与长大,进而阻止柱状晶的生长,使柱状晶提前向等轴晶转变,中心等轴晶率提高。综合考虑圆坯中心等轴晶率、表面和内部裂纹控制及浇铸安全和生产率,37Mn5钢150mm圆坯合适的连铸工艺参数为:过热度为(20±5)℃,拉速为2.5m.min-1,二冷水分布为35∶28∶26∶11。
In order to control the quality of continuous casting round billet of oil well, the solidification and heat transfer mathematical model of continuous casting round billet was established based on the sheet moving method. The solidification microstructure of 37Mn5 steel 150mm round billet was simulated by CA-FE module of Procast software. The center equiaxed rate simulation result is consistent with the industrial test results. Based on this, the criterion of columnar-equiaxed crystal transition was established. Based on this criterion, the center equiaxed grain rate prediction results show that reducing the superheat, increasing the pulling speed and reducing the cooling water distribution ratio of the second cooling section can reduce the temperature gradient in the solid-liquid mixing zone and enlarge the range of the cooling zone, which is in favor of Crystal nucleation and growth, thereby preventing the growth of columnar crystals, the columnar crystal advance to the equiaxed crystal transformation, the center equiaxed crystal rate increased. Considering the equiaxed grain rate of round billet center, surface and internal crack control and casting safety and productivity, the suitable continuous casting process parameters of 37Mn5 steel 150mm round billet are as follows: superheat degree is (20 ± 5) ℃, casting speed is 2.5m . min-1, two cold water distribution of 35:28:26:11.