两相区铸造制备ZK60-2Ca半固态坯料的部分重熔组织

Partially Remelting Microstructures of ZK60-2Ca SSM Ingot Prepared by Two-Phase Region Casting

为了使坯料获得既细小又圆整的晶粒组织，采用两相区铸造法制备了ZK60-2Ca镁合金半固态坯料，并利用电阻炉加热进行部分重熔。结果表明，适当控制加热温度和保温时间，坯料部分重熔时可获良好的触变结构。水冷铜型浇注时，在610℃下保温10～15min时可获得较理想的触变结构，晶粒尺寸达32.36bμm，圆整度达1.68；石墨型浇注时，其晶粒平均直径为33.61μm，圆整度达1.47。适当降低铸造冷却速率，即采用石墨型，能提高二次重熔组织的均匀性和稳定性。

To obtain billet with small and spherical grain structure, the ingot of ZK60-2Ca magnesium alloy was prepared by two-phase region casting, and then the ingot was partially remelting by electric resistance furnace. The results indicate that desirable thixotropic microstructure in the ingot prepared can be obtained by proper controlling remelting temperature and holding time. Using the water-cooled copper mould, desirable thixotropic microstructure can be obtained at 610℃ for 10～15 min, where the average diameter of grain reaches 32.36 μm and the roundness is 1.68. With the graphite mould, the average grain diameter is 33.61 μm and the roundness reaches 1.47. Meanwhile, the cooling rates during casting also affect the partial remelting progress. Through reducing the cooling rate properly, the uniformity and stability of the partial remelting microstructure are improved.