Study on the aluminium-magnesium-silicon alloy (5th Report)

Abstract

This is to report on the study of the effect of the small addition of manganese, chromium, nickel, zinc, tin, antimony, lead and cobalt on the mechanical properties and electrical conductivity of Al-(Mg+Si_??_1.1%) ternary alloy with different Mg/Si weight ratis.The findings are as follows:(1) The addition of manganese and chromium gives the largest effect on the decrease of electrical conductivity of the extruded products of Al-Mg-Si alloy, especially chromium, of all the elements. It seems due to the difficulty of precipitating chromium from the ingot in supersaturated solid solution.(2) In a practical view point, the properties of extruded product of Al-Mg-Si alloy added with less than 0.03% manganese or chromium barely can meet the requirement of 2EC-T6 or 6101-T6 standard, where the electrical conductivity of 55% TAGS and ultimate tensile strength of 20.3kg/mm2.(3) Zinc besides manganese and chromium fairly increases the strength of as-extruded products of Al-Mg-Si alloy. It can not be explained by the extrusion texture "press-effect" because the structure of extruded products containing zinc shows enough recrystallization in the state of as-extruded. Therefore the closer investigation on the effect of zinc on the precipitation of Mg2 Si ("hardenability") may be required.(4) The mechanical properties and electrical conductivity of extruded products of Al-Mg-Si alloy are not particularly influenced by the addition of nickel, tin, antimony, lead and cobalt in the present experiment.