The Effect of High Speed Direct Chill Casting on Microstructure and Mechanical Properties of Al-Mg-Si-Fe Alloy

In this paper, high-speed direct chill casting was investigated to improve the microstructure and mechanical properties of Al-Mg-Si-Fe alloy billet. With the increase of casting speed, the size of grain decreased from 82 to 23 μm; Fe-containing intermetallic phase significantly refined and transformed from bone to short rod-like shape. The macrosegregation of Mg, Si and Fe was alleviated from center to surface of the billet at high casting speed. The Mg, Si and Fe elements also had a homogeneous distribution in the grain with the increase of casting speed. Moreover, EPMA analysis indicated that solid solubility of Mg, Si and Fe improved when casting speed increased from 100 to 300 mm/min. Hardness and tensile properties all improved with the high casting speed. The high-speed direct chill casting was an effective mean to overcome the disadvantage of conventional casting process.