材料期刊网

制备Mg--3Sn--Mn合金型材, 研究了连续流变成形工艺条件对制品组织的影响机理。结果表明: 当轧辊转速一定而合金浇注温度在690--750℃变化时, 随着浇注温度的降低, 结晶前沿的成分过冷度增大, 合金中心固相率增加, 从而使制品边部柱状晶区增大, 中心等轴晶区减小, 等轴晶区的晶粒平均直径减小。当合金浇注温度一定, 二轧辊转速在0.052--0.087 m · s ^-1变化时, 随着轧辊转速的减小凝固界面趋于稳定, 合金在辊靴型腔中随剪切时间的增加制品边部柱状晶区减小, 中心等轴晶区增大。浇注温度为690℃、轧辊转速为0.052 m · s^-1时制备的断面为5 mm x 50 mm的镁合金型材,其表面质量和组织良好, 制品晶粒平均直径为27 μm。

Mg–3Sn–Mn alloy profiles have been successfully manufactured by the continuous rheo–forming equipment self–designed, and the effects of process conditions on the microstructures of the products were investigated. The results show that when the roll is at a certain speed and the casting temperature varies from 690^oC  to 750^oC with the decrease of casting temperature, the composition supercooling in front of solid–liquid interface and the solid fraction in the center increase, so, the width of columnar grain zone near the edge of the product increases, the equiaxed grain zone in the central position decreases, and the average diameter of grains in the equiaxed grain zone decreases. When casting temperature is kept constant and roll speed varies from 0.052 m·s⁻¹ to 0.087 m·s⁻¹, with the decrease of roll speed, the solid–liquid interface tends to be stable and the melt is subjected to the shear in the roller–shoe cavity for a long time, so, the width of columnar grain zone near the edge of the product decreases and the width of equiaxed grain zone in the central position increases. When the casting temperature is 690^oC  and roll speed is 0.052 m·s⁻¹, magnesium alloy profiles with cross–section of 5 mm×50 mm have been obtained, the surface and microstructure of the products are excellent, and the average grain size of the product is 27 μm.