Q345B宽厚板微观组织优化数值模拟

Numerical simulation on optimization of microstructure on Q345B wide and heavy plate

为改善Q345B宽厚板中心偏析缺陷,采用CAFE法对连铸凝固末端的铸坯断面微观组织进行模拟计算,研究钢水过热度和铸坯拉速对凝固组织的影响规律。研究结果表明:适当减小过热度和降低拉速能够提高中心等轴晶率,增加晶粒数,减小晶粒平均半径。当钢水过热度由34℃降低至25℃,拉速由0.68 m/min调整到0.56 m/min后,断面凝固组织中心等轴晶率增加15.1%,晶粒平均半径减小2 135μm,晶粒数增加367.4%,且模拟组织与试验铸坯得到的微观组织形貌基本一致,铸坯中心偏析缺陷也得到有效改善。

In order to improve the centerline segregation of Q345B wide and heavy plate, the microstructure of the cross section of casting blank was obtained by CAFE approach. And the influence of the superheat and casting speed on the microstructure of billet was analyzed. The results show that decreasing the superheat and casting speed properly can increase the isometric crystal rate and the number of grains, and decrease the average radius. After adjusting the superheat from 34℃ to 25℃ and casting speed from 0.68 irdmin to 0.55 m/min in ProCAST, the center equiaxial crystal rate increases about 15%, the average grain radius decreases by 2 135 gm, and the number of grains increases about 367.4%, which is basically identical with the microstructure statistical data of experimental billet. The centerline segregation of billet gets improved effectively.