双辊连铸AZ61镁合金薄带坯的工艺与显微组织

Processing and Microstructure of AZ61 Thin Strip Prepared by Twin Roll Casting

采用规格为φ250 mm×150 mm的立式双辊连铸系统制备了3~4 mm厚1、50 mm宽的AZ61镁合金薄带坯;研究了水口形状和浇铸温度等连铸工艺参数对薄带坯显微组织和表面质量的影响。结果表明:采用B型水口制备的AZ61薄带坯的表面裂纹较少,表面质量较好;随着浇铸温度的降低,薄带坯表面裂纹数量增多,AZ61薄带坯的组织由先析-αMg和过饱和-αMg基体组成;当浇铸温度为630℃时,薄带坯的组织细小均匀;当浇铸温度介于固相线和液相线之间时,薄带坯组织中存在局部粗大的-αMg树枝状晶。

AZ61 thin strips with the thickness of 3-4 mm and width of 150 mm were prepared by a vertical twin roll caster(φ250 mm×150 mm) and the effect of different nozzles and casting temperatures on microstructure and surface quality was examined.As the results,the cast strips prepared by B nozzle had less surface cracks than those by A nozzle.The number of the surface cracks of the strips increased with the decrease of the casting temperature.Microstructure of the AZ61 strips consisted of the first crystallized α-...