Two of the most common alloys for extrusion are 6061 and 6063. Although they possess many of the same qualities, they each offer their own distinct properties that mean manufacturers need to do their research when deciding between them.
The second most popular aluminum for extrusion, 6061 is precipitation-hardened and uses magnesium and silicon as its major alloying elements. It was first developed in 1935 as part of the early advances in the aircraft industry. It offers good weldability and machinability, good joining characteristics, accepts applied coatings well, and is highly corrosion resistance while having a high strength to weight ratio.
In contrast, 6063 is the most popular aluminum used for extrusion. It also uses magnesium and silicon as its alloying elements. Its unique properties allow it to be formed into complex shapes with very smooth surfaces, making it fit for anodizing. Its major drawback compared to 6061 is that it does not have the same level of strength.
In comparing the specific properties of the two alloys, 6061 has a density of 2.7 g/cm cubed. The Young’s modulus is rated at 68.9 GPa with a tensile strength of 124-290 MPa. The elongation at break is 12-25%. It has a melting temperature of 585 degrees Celsius, thermal conductivity of 151-202 W/(m·K), and a specific heat capacity of 897 J/ (kg·K). The linear thermal expansion coefficient is 2.32 x 10−5 K−1. Finally, the volume resistivity is 32.5–39.2 nOhm·m.
By contrast, 6063 offers a density of 2.69g/ cm3. It’s Young’s modulus is 68.3 GPa and it has a tensile strength of 145–186 MPa. It has a slightly higher elongation at break at 18-33%. 6063 offers a melting temperature of 615 °C, thermal conductivity of 201-218 W/(m·K), and a specific heat capacity of 900 J/ (kg·K). The linear thermal expansion coefficient is 2.34 x 10−5 K−1, and the volume resistivity is 30-35 nOhm·m.
