Effect of Magnesium on Tensile Strength of Cast Aluminum Alloy Using Sand Casting Method

Abstract

It has been proven over the years that pure aluminum is ductile, light
weight, brittle and has low tensile strength. This study was carried out
and aimed at improving the mechanical properties with focus on
tensile strength of the cast aluminum by alloying it with magnesium.
This is as a result of its high strength and low density. The alloying
aluminum-magnesium (Al-Mg) was carried out using sand casting
method because of cost effectiveness and ease availability. The sand
mold was prepared with green sand which is made up of silica sand,
binders and water. The pattern for the casting is 200mm by 14mm; it
was then placed in the mold cavity and rammed. Aluminum craps of
2kg by weight is placed in the crucible furnace and heated to a
temperature of 750oC. Powdered magnesium of 45% composition is
added to the molten aluminum and mixed together using a stir casting
machine and poured into the mold cavity at a temperature of 730oC
and allowed to solidify. This process was repeated for 6%, 8%, 10%,
12% and 14% weight composition of magnesium alloy. The cast
specimen was then machined to specification and dimension to enable
the tensile strength test to be carried out using Avery-Dimensional
Universal Testing Machine. It was observed that at 4% Mg
composition the tensile test result value was lowest and this value
increase as the composition of Mg was varied and at 14% Mg
composition, the tensile test result value was at highest. It was
concluded therefore that the composition of Mg in Al-Mg alloy has a
positive effect on the cast material, that as the composition of Mg
increases from 4%-14%, the tensile strength of the cast material also
increases.