连铸速度和轧制变形对HCCM立式连铸铝白铜棒材组织性能的影响

Effect of continuous casting speed and cold rolling on microstructure and properties of aluminium white copper bars produced by HCCM vertical continuous casting

采用HCCM立式连铸技术制备铝白铜棒坯,并进行不同压下量的轧制变形,研究连铸速度和轧制变形对棒材组织性能的影响。通过拉伸实验分析不同状态下棒材的力学性能变化,利用光学显微镜(OM)、电子背散射衍射系统(EBSD)、扫描电子显微镜(SEM)、能量色散谱(EDS)观察棒材的微观组织形貌。结果表明:当金属液温度为(1300±5)℃、热型加热温度为(1250±5)℃、冷却水流量为400L/h、连铸拉坯速度为0.5~2.0mm/s时,可制备出具有连续柱状晶组织和优良力学性能的铝白铜棒坯。随着连铸速度由0.5mm/s增大至2.0 mm/s时,粗大柱状晶组织逐渐转变为与连铸方向呈一定角度的柱状晶组织和等轴晶组织,抗拉强度呈增大趋势,为311~418 MPa,断后伸长率由69.2%降低至64.9%;存在于晶界处及枝晶间的富铝β相数量增多、分布变得均匀。随着冷轧变形量由0增大至80%,抗拉强度呈线性增长;继续增大变形量,抗拉强度增速放缓。随着冷轧变形量由0增大至40%,断后伸长率呈线性降低;当冷轧变形量为40%~94%时,断后伸长率稳定在5%左右,展现出柱状晶组织较好的可持续加工性能,但连铸速度及轧制变形对柱状晶的影响机理有待进一步验证。

The HCCM vertical continuous casting technology was used to prepare aluminum white copper bar billets,and rolling with different reduction was carried out,so as to study the effect of continuous casting speed and rolling deformation on the microstructure and properties.The mechanical properties of the bar under different conditions were analyzed by tensile test.The microstructure and orientation of the bar were observed by OM,EBSD,SEM and EDS.The results show that,when the temperature of the molten metal is(1300±5)℃,the heating temperature is(1250±5)℃,the cooling water flow rate is 400 L/h,and the continuous casting billet speed is 0.5-2.0 mm/s,aluminum white copper bar billets with columnar crystal structure along the continuous casting direction and excellent mechanical properties can be prepared.With the continuous casting speed increasing from 0.5 mm/s to 2.0 mm/s,the coarse columnar crystal structure gradually changes into the columnar crystal structure with an angle to the continuous casting direction and equiaxed crystal structure,and the tensile strength tends to increase in the range of 311-318 MPa,and the elongation decreases from 69.2%to 64.9%.In addition,the aluminum-richβphases increase and the distribution becomes more uniform.With the cold rolling deformation increasing from 0 to 80%,the tensile strength increases linearly.With the further increase of deformation,the growth rate of tensile strength slows down.With the cold rolling deformation increasing from 0 to 40%,the elongation decreases linearly.When the cold rolling deformation is in the range of 40%-94%,the elongation is stable at about 5%,showing good sustainable processing performance of columnar crystal structure.However,the influence mechanism of continuous casting speed and rolling deformation on columnar crystal needs to be further verified.