There are two kinds of aluminum alloy ( AA): casting alloy and wrought alloy which are suitable for different applications. Wrought aluminum alloy, such as the AA 6061, are worked by extruding, rolling or forging them into specified shapes. Heat-treatment or cold processing can increase AA’s hardness, corrosion resistance and other expected aluminum alloy properties.
Aluminum Alloy 6061-T6 is a precipitation-hardened aluminum alloy containing magnesium and silicon as its major alloying elements, which are originally called “Alloy 61S”. AA 6063-T5 is another aluminum alloy which containing the same alloying elements as AA 6061-T6.
The alpha-numeric suffixes attached to alloys, such as 6061-T6, represent the temper, or degree of hardness. They also represent the method by which the hardness was obtained. Temper is a process of heat treating, which is used to increase the toughness of iron-based alloys. Tempering is usually performed after hardening, to reduce some of the excess hardness, and is done by heating the metal to some temperature below the critical point for a certain period of time, then allowing it to cool in air. The exact temperature determines the amount of hardness removed, and depends on both the specific composition of the alloy and on the desired properties in the finished product.
In the case of the 6061-T6 aluminum alloy, the “T6” indicates that it was a heat-treating solution and artificially aged. “T5” indicates that heat treatment and naturally aged. Naturally, aging allows the aluminum alloy aged at an elevated temperature in low-temperature ovens while artificially aging let the AA aged at an elevated temperature in high-temperature ovens.
Hence, to find the difference between them, let’s take a look at the chemical composition & thermal properties first.
Chemical Composition
AA 6061-T6
AA 6063-T5
Aluminum (Al)
95.9 to 98.6
97.5 to 99.4
0.8 to 1.2
0.45 to 0.9
Silicon (Si)
0.4 to 0.8
0.2 to 0.6
Iron (Fe)
0 to 0.7
0 to 0.35
Copper (Cu)
0.15 to 0.4
0 to 0.1
Chromium (Cr)
0.04 to 0.35
0 to 0.1
Zinc (Zn)
0 to 0.25
0 to 0.1
Manganese (Mn)
0 to 0.15
0 to 0.1
Titanium (Ti)
0 to 0.15
0 to 0.1
Thermal properties
AA 6061-T6
AA 6063-T5
Specific Heat Capacity
>900 J/kg-K
>900 J/kg-K
Thermal Conductivity
170 W/m-K
210 W/m-K
Thermal Expansion
24 µm/m-K
23 µm/m-K
Melting Temperature
585 °C (1,085 °F)
615 °C (1,139 °F)
Different chemical composition and temper treatment would behave in mechanical properties and hardness. T6 would be higher hardness than T5 while other properties are similar.

Mechanical Properties

Wechsler Hardness
>12 HW
>8 HW
Tensile Strength (Ultimate)
>290 MPa
>140 MPa
>290 MPa (42,000 psi)
>140 MPa (20,000 psi)
Tensile Strength(Yield)
>240 MPa
>130 MPa
>240 MPa (35,000 psi)
>130 MPa (19,000 psi)
Elongation at Break
Elastic (Young’s, Tensile)
69 GPa
68 GPa
69 GPa
68 GPa
Poisson’s Ratio
AA 6061-T6 features a very high hardness and good weldability and it is mainly used in:
  • bicycle frames and components
  • fly fishing reels
  • the pioneer plaque
  • the upper and lower receivers of many nonmail-spec AR-15 rifle variants.
  • material used in some ultra-high vacuum (UHV) chambers
  • parts for remote-controlled model aircraft, notably helicopter rotor components
AA 6063-T5 allows complex shapes to be formed with very smooth surfaces fit for anodizing. It is used in:
  • Windows and doors frame
  • Curtain wall frame
  • metal Roofs

High quality and creative metal carport covers & polycarbonate patio covers is Sunshield eternal shelter. Hence, we use the Aluminum Alloy 6061 – T6 as the profile of polycarbonate shelter and swimming pool enclosures. We are a large carport and patio shelter manufacturing enterprise which set design, production, and sales in one, with 10,000+ production and storage base and 10+ years experienced structural engineers in carport shelter industry. If you are interested in outdoor shelter, please feel free to contact us.

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