Aluminum alloys 6061 and 6063 are two of the most common for extrusion. They have applications in aerospace, construction, transportation, recreational products, and numerous other industries.
They share many similar properties, making it difficult for some designers to determine which is right for their purposes. And while the differences between the alloys are subtle, it’s essential to understand them before making a decision.
This article will help you understand the advantages and disadvantages of each alloy so you can decide which one is the best fit for your project.
Often referred to as “structural aluminum,” alloy 6061 is a common and reliable alloy. As a member of the 6000 series, it is primarily alloyed with magnesium and silicon. The magnesium increases its strength, and the silicon reduces its melting point.
International guidelines dictate that, for an aluminum alloy to be considered 6061, its magnesium content has to be between 0.8 and 1.2%, and its silicon content has to be between 0.4 and 0.8%.
Design engineers use alloy 6061 in many different products as its physical properties are very well rounded. Applications range from structural and building products to recreation and sports equipment to aerospace engineering.
This alloy offers good relative corrosion resistance, weldability, and tensile strength. Temper treatment can improve its tensile strength even further, which involves artificial aging in an aging oven. Alloy 6061’s good workability and machinability also make it a desirable candidate for extruded products.
Additionally, in comparison with more specialized aluminum alloys, 6061 is widely available and relatively low cost. It does not rank first in any of the charts of physical properties. But this alloy is exceptionally versatile and easy to fabricate in most metal-forming techniques.
Often referred to as “architectural aluminum,” alloy 6063 has been optimized for extrudability. It provides a high-quality surface that can be easily anodized.
Alloy 6063 is also a member of the 6000 series. Therefore its main alloying components are also magnesium and silicon, although in smaller quantities than 6061. Chemical composition guidelines state that for an aluminum alloy to be classified as 6063, the magnesium content needs to be between 0.45 and 0.9%, and the silicon content has to be between 0.2 and 0.6%.
This alloy shares many of its characteristics with 6061, though it has some key differences. Alloy 6063 offers very good corrosion resistance, particularly if an appropriate surface finish is applied. It also offers good weldability, brazeability, and workability. And it provides moderately good tensile strength and fair machinability.
Like 6061, this alloy is very popular for extrusions. Designers use it in various applications, including architectural, recreational equipment, furniture, and others. You’ll generally find alloy 6063 in applications where exposure to weather or water is expected. That’s because it resists corrosion better than 6061.