流变铸轧AZ91D镁合金半固态组织演变特点

采用旋转管浇注法制得AZ91D镁合金半固态浆料,在水平双辊铸轧机上进行了流变铸轧试验研究,对铸轧前后组织的特点进行了分析比较.结果表明,铸轧可使初晶更加圆整,620 ℃浇注温度下,静置时间短,铸轧对初晶圆整化效果更加显著;铸轧后初晶尺寸略微减小,分布更加均匀;铸轧后薄板面上的初晶晶粒密度低于半固态浆料的晶粒密度,620 ℃浇注温度下,铸轧后晶粒密度显著下降.

Evolution of Microstructural Characteristics of Rheo-rolling Semi-solid AZ91D Magnesium Alloy

Semi-solid slurry of AZ91D magnesium alloy was prepared by rotary pouring method, and rheo-rolling experiment was carried out on a horizontal twin-roll caster, furthermore, the microstructure of the alloy before and after rheo-rolling process was analyzed comparatively. The results show that primary phase becomes more rounds after rheo-rolling process. Desirable spheroidization can be observed in the rheo-rolled AZ91D magnesium alloy with pouring at 620℃ and holding for a short time. Average grain size of primary phase is slightly decreased with more homogeneous distribution in the rheo-rolled AZ91D magnesium alloy. Grain density of primary phase in the rheo-rolled AZ91D magnesium alloy sheet surface is less than that in semi-solid slurry. Furthermore, grain density is significantly reduced in the alloy with pouring at 620 ℃ after rheo-rolling.