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研究了不同铸造速度下截面尺寸为300 mm×800 mm的AZ31镁合金大规格板坯的宏观偏析及宏观组织。结果表明,偏析区域出现在距离板坯表面20~30 mm范围内,板坯心部偏析小。宏观组织可分为表面激冷区,粗大柱状晶区和内部等轴晶区。低速铸造可减轻宏观偏析,随铸造速度增加,整体晶粒尺寸先增大后减小,表面柱状晶区宽度减小。高速铸造时晶粒尺寸小,但不均匀。合理的铸造速度为32 mm/min。
The macrosegregation and macro-structure of AZ31 magnesium alloy large size slab with 300 mm × 800 mm section length under different casting speeds were studied. The results show that the segregation zone appears in the range of 20-30 mm from the slab surface, and the segregation of slab core is small. Macroscopic organization can be divided into surface quench zone, coarse columnar and inner equiaxed zone. Low-speed casting can reduce macro-segregation, with the casting speed increases, the overall grain size first increases and then decreases, the surface columnar grain size decreases. High-speed casting grain size small, but uneven. Reasonable casting speed of 32 mm / min.