Aluminum 6061 vs 6063
Aluminum 6061 and 6063 are two of the most widely used alloys in aluminum extrusion. Each grade has distinct properties suited for specific applications—neither is inherently better than the other. This article provides a clear and direct comparison of 6061 and 6063 to help you choose the right material for your needs.
Composition Table: 6061 vs 6063
| Element | 6061 (% by weight) | 6063 (% by weight) |
|---|---|---|
| Aluminum (Al) | Balance | Balance |
| Magnesium (Mg) | 0.8 – 1.2 | 0.45 – 0.90 |
| Silicon (Si) | 0.4 – 0.8 | 0.20 – 0.60 |
| Copper (Cu) | 0.15 – 0.40 | ≤ 0.10 |
| Chromium (Cr) | 0.04 – 0.35 | ≤ 0.10 |
| Iron (Fe) | ≤ 0.7 | ≤ 0.35 |
| Zinc (Zn) | ≤ 0.25 | ≤ 0.10 |
| Manganese (Mn) | ≤ 0.15 | ≤ 0.10 |
| Titanium (Ti) | ≤ 0.15 | ≤ 0.10 |
| Other Elements | ≤ 0.15 | ≤ 0.15 |
Effects of Different Alloying Elements
The main compositional differences between 6061 and 6063 alloys lie in their magnesium, silicon, copper, and chromium content. Each of these elements plays a specific role in determining the alloy’s characteristics:
Magnesium (Mg):
Increases strength and enhances the alloy’s response to heat treatment. Higher magnesium content in 6061 gives it greater mechanical strength compared to 6063.
Silicon (Si):
Promotes a finer grain structure and improves extrudability. While both alloys contain silicon, the slightly higher content in 6061 also contributes to its strength.
Copper (Cu):
Significantly increases hardness and strength but can reduce corrosion resistance. 6061 contains more copper than 6063, contributing to its superior mechanical properties.
Chromium (Cr):
Improves resistance to corrosion and reduces susceptibility to grain boundary corrosion. 6061 contains added chromium, further enhancing its durability, especially in demanding environments.
Mechanical Property: 6061 vs 6063
6061 offers significantly higher tensile and yield strength than 6063, along with greater hardness, making it better suited for structural and load-bearing applications with improved wear resistance.
| Property | 6061-T6 | 6063-T6 |
|---|---|---|
| Ultimate Tensile Strength | 290 MPa (42 ksi) | 205 MPa (30 ksi) |
| Yield Strength | 240 MPa (35 ksi) | 180 MPa (26 ksi) |
| Elongation at Break | 8–10% | 8–10% |
| Brinell Hardness | 95 | 73 |
| Modulus of Elasticity | 68.9 GPa | 68.3 GPa |
| Density | 2.70 g/cm³ | 2.70 g/cm³ |
Differences in Workability: 6061 vs 6063
Aluminum 6061 and 6063 exhibit different workability characteristics due to their unique compositions.
Extrusion Performance:
6063 produces a smoother extruded surface than 6061.
6061 requires greater extrusion force compared to 6063.
Machinability:
6061 is harder and achieves higher machining precision, making it well-suited for precision parts.
6063 is softer, resulting in lower machining accuracy than 6061.
Weldability:
Both 6061 and 6063 have good weldability.
6063 produces a better weld surface, making it more suitable for decorative applications.
Welded areas of 6061 may be affected during heat treatment, potentially reducing local strength.
Corrosion Resistance Comparison: 6061 vs 6063
Both 6061 and 6063 have good corrosion resistance. However, 6063 performs slightly better because it contains less copper. Copper can increase the risk of corrosion, especially in harsh environments.
Cost Comparison: 6061 vs 6063
The processing difficulty of 6061 is higher than that of 6063, resulting in a slightly higher manufacturing cost for 6061.
Typically, 6061 undergoes T6 heat treatment to further increase its strength. T6 treatment requires water quenching equipment, making the production cost of 6061-T6 slightly higher than that of 6061-T5.
Conclusion and Application Analysis
6061 offers higher strength and better machinability, while 6063 provides superior extrudability, a smoother surface finish, and better corrosion resistance.
Aluminum alloy 6061 commonly used for structural components, precision machined parts, automotive parts, bicycle frames, aerospace fittings, and applications that require higher strength and precision machining.
Aluminum alloy 6063 commonly used for architectural profiles, window frames, door frames, decorative trims, and applications where surface finish and corrosion resistance are emphasized.