Grade Guide: Aluminium 6061 vs 6063

Overview

Aluminium 6061 and Aluminium 6063 alloys are widely popular materials within the extrusion industry.

Each alloy is almost identical in composition and mechanical properties with only slight differences in the added elements. Both contain magnesium for increased strength and silicon to reduce the melting temperature; the price difference between the two is largely negligible.

Aluminium alloy composition

Aluminium 6061 can contain up to twice the percentage of iron, and usually contains more copper, chromium and silicon than Aluminium 6063. On average, there is up to 3.5% greater aluminum content in the latter.

To enhance them for a broader range of applications, you can heat treat both materials.

Key attributes

Aluminium 6061 is ideal for structural applications and construction projects that require high-strength aluminium extrusions.

Depending on the heat treatment process, these products can have different material hardness grades. The Brinell scale is the standard measurement system for qualifying material hardness – Aluminium 6061 typically has a Brinell hardness value of 95, while Aluminium 6063 sports a 73.

Use cases of Aluminium 6061 & 6063

Both alloys have far-reaching applications including transportation components, recreation products, machinery, equipment and consumer durables. When comes to consumer durables, this can include everything from electrical components, conduits, furniture, appliances, railings, pipe, irrigation system tubing, architectural items, building products as well as boats and motor vehicles.

However, each one excels under specific circumstances.

Aluminum 6061 is the preferred material for structural applications such as braces, frames, recreation products, trailers, truck beds and aerospace.

Professionals often refer to Aluminium 6063 as “architectural aluminium,” since it can be soft-anodised for more aesthetic versatility in architectural and building applications.

Working on a project exposed to the elements? When high strength is not a major factor, consider using this one. With its superior corrosion resistance and weather endurance, the alloy is perfect for use in window frames, door frames, sign frames and roofs.

Round tubing extrusions frequently use Aluminium 6063 due to its higher product strength. Furniture, shelving, stairs, pipes and trim all make use of this alloy. While Aluminium 6061 is the more robust material in most extrusion configurations, Aluminium 6063 is preferred for this particular extrusion.

Aluminium 6061 round tubes are found in products that don’t necessarily require maximum strength such as sleeves, couplers and framework. However, square tubing extrusions do prefer Aluminium 6063 as it provides a superior finish and more corrosion resistance.

Structural and trim applications make use of both materials. Extruded angles use Aluminium 6061 to provide superior strength for structural projects. Architectural trim projects opt for Aluminium 6063 as it offers a more attractive finish.

Extruded channels again utilise Aluminium 6061 for its superior strength in structural supports, while working professionals use Aluminium 6063 for flashier applications such as trim.

What have we learnt?

In sum, while they may be quite similar composition-wise, the applications of these alloys can vary widely.

Due to its superior strength, most professionals favour Aluminium 6061 for structural applications and construction projects that require high-strength aluminium extrusions with a lower melting temperature, lower thermal conductivity and lower heat capacity.

Aluminium 6061-T6 has a higher yield strength and fatigue strength when compared to Aluminium 6063-T6. It has good extrudability, machinability and weldability along with good corrosion resistance – although it’s less resistant than Aluminium 6063.

For projects that require an extrudable aluminium alloy with superior corrosion resistance, good surface quality and easily anodised, choose Aluminium 6063.

This material offers good workability, weldability, surface quality and corrosion resistance; it also has superior extrudability compared to Aluminium 6061. Professionals often refer to Aluminium 6063 as architectural aluminium, as it’s easier to anodise and create attractive coloured finishes.