Effect of pouring process on the microstructures of semi-solid AlSi7Mg alloy

The effect of different pouring temperatures and different pouring heights, the distance between the mouth of the pouring ladle and the top of the mol d, on the microstructure of AlSi7Mg alloy have been researched in the paper . When the pouring temperature is close to the liquidus temperature, the pr imary alpha -Al in 'the billets of AlSi7Mg alloy solidified into spherical and nodular fine grains distributed homogeneously. The optimum pouring temp erature for semi-solid AlSi7Mg billet with spherical or nodular primary alp ha -Al is 615 degreesC. At the same pouring temperature, the higher the pou ring ladle, the more easily the spherical and nodular primary alpha -Al obt ained in the semi-solid AlSi7Mg billet. When the pouring temperature is clo se to the liquidus temperature and the pouring ladle is relatively high, it is the great cooling rate, the flow of the molten allay caused by pouring and the large simultaneous solidification region induced by the near liquid us temperature, that promote the formation of spherical or nodular primary cr-Al.