Optimal Control of Aluminium Alloy 6063 Chemical Composition

We talked about Chemical composition which is the determinant of aluminum profile performances in a general way; we also talked about Aluminium Alloy 6061 mechanical performance before.

Architecture Aluminium Alloy 6063-T5 profile must have certain mechanical properties. The tensile strength and yield strength increased with the content of other conditions.The strengthening phase of alloy 6063 is mainly Mg₂Si, however, how much should the amount of Mg, Si, and Mg₂Si be taken?

The Mg₂Si phase is composed of two magnesium atoms and one silicon atom, and the atomic mass of magnesium is 24.31, the atomic mass of silicon is 28. In the Mg₂Si compound, the mass ratio of magnesium-silicon is 1.73:1.

Therefore, according to the above analysis results, if the ratio of magnesium-silicon content is greater than 1.73. In addition to the Mg₂Si phase of magnesium alloy, there is excess magnesium, whereas the ratio is less than 1.73, the silicon in addition to the formation of the Mg₂Si phase and the remaining silicon.

Magnesium excess is harmful to the mechanical properties of alloys. Magnesium is normally controlled within 5%, the total amount of Mg₂Si is controlled within 0.79%. When the silicon excess is 0.01%, the mechanical property of alloy σb is about 218Mpa, which has greatly exceeded the national standard performance, and the excess silicon from 0.01% goes up to 0.13%. And 13% σb can be increased to 250Mpa or 14.6%. To form a certain amount of Mg₂Si, we must first consider the silicon loss caused by impurities such as Fe and Mn, which is to ensure that there is a certain amount of excess silicon. In order to make the magnesium in the 6063 alloy fully match the silicon, the actual ingredients must be consciously made for Mg: Si < 1.73. The glut of magnesium not only weakens the strengthening effect but increases the cost of the product.

So, the composition of the 6063 alloy is generally controlled as: Mg：0.45％-0.65％；Si：0.35％-0.50％；Mg：Si=1.25-1.30; Impurities Fe control within < 0.10% – 0.25%; Mn < 0.10%.