Aluminum alloys combine aluminum with other metals to achieve different physical and chemical properties while decreasing costs. Aluminum is easy to combine with other metals and thus has many alloys, such as 7075 aluminum. This alloy has exceptional strength compared to weight, making it a suitable choice for industries like aerospace and automotive.
7075 aluminum is a heat-treatable aluminum alloy that uses zinc as the primary alloying element. Other elements in this alloy include magnesium, copper and chromium. Alloy 7075 is one of the strongest commercially available and is the strongest among the 7XXX series of aluminum alloys. The alloy is prized due to its high strength-to-weight ratio. It can be formed by regular methods but requires more care and precision.
The metal gets its name from the Aluminum Association, which creates standardized names for alloys based on compositions and alloying elements. The first digit classifies it as part of the 7XXX group, which uses zinc as the primary alloying element. The second number, “0,” represents an alloy that uses commercial aluminum with existing impurity levels. The last two numbers represent the particular alloy due to its specific percentages of alloying elements.
7075 aluminum often has further numbers and letters following the four-digit code. These temper designations represent different heat treatments used to change the alloy’s strength. A few standard temper designations are listed below.
This designation represents un-heat-treated aluminum 7075. Properties of this temper include lower tensile and yield strength and a lower elongation percentage.
A T6 designation represents a solution that is heat-treated and artificially aged. 7075-T6 aluminum is the strongest condition. The temper is achieved by a homogenizing cast at 350 degrees Celsius for several hours, followed by quenching and aging at 120 degrees Celsius for 24 hours.
7075-T6 aluminum is heat-treated and stabilized. The temper is achieved by averaging past the peak hardness, often by aging at 100 to 120 degrees Celsius for several hours, then at 160 to 180 degrees Celsius for 24 hours or more. This temper produces aluminum with lower tensile and yield strength but a higher elongation percentage.
The aluminum 7075 alloy composition is 5.1% to 6.1% zinc, 2.1% to 2.9% magnesium, 1.2% to 2.0% copper and 0.18% to 0.28% chromium. Other elements include silicon, iron, manganese and titanium. This unique composition results in particular chemical and physical properties that distinguish this alloy from different types of aluminum.
The main chemical property that matters relating to aluminum is its corrosion resistance. This alloy is less corrosion-resistant than other aluminum alloys due to the presence of copper. 7075 aluminum is susceptible to intergranular corrosion, a localized corrosion that forms along grain boundaries in metals. Due to this chemical property, 7075 aluminum may have protective coatings applied to prevent corrosion.
Here are a few physical properties of 7075 aluminum. These values represent the T6 condition of the alloy:
Other 7075 aluminum properties include a relatively low density of 2.81 g/cm3, high electrical and thermal conductivity, and a melting point of about 640 degrees Celsius.
Like other aluminum materials, 7075 has unique properties that suit particular applications. It is highly used in industries that need a lightweight yet durable material.
7075 aluminum has frequent use in aircraft manufacturing. Aircraft structural members, fuselages and wings may use the alloy. Other uses include helicopter rotor blades and missile parts. The alloy typically serves applications where cheaper alloys are not suitable.
The automotive industry uses 7075 aluminum for various components, including gears and shafts, fuse parts and regulation valve parts. The alloy is exceptionally lightweight while providing durability to withstand wear.
The 7075 aluminum alloy is often used in highly stressed structural applications, such as keys and small gears. The alloy is also frequently used in structural components like bike frames, giving them strength while limiting their weight.
No, aluminum 7075 is not generally stronger than steel, but a few steel grades are comparable in strength to 7075 aluminum. For example, the tensile strength of AISI 1015 steel is between 115 and 234 MPa or 61,000 and 61,500 psi. 7075-T6 aluminum has a tensile strength of about 572 MPa or 83,000 psi. Another type of steel, AISI 1045, can have a tensile strength of up to 700 MPa or about 101,500 psi.
While this aluminum alloy has a lower overall strength, its strength-to-weight ratio is much higher than steel’s. This difference between the metals means that each has particular applications. The two metals also differ in other properties, such as electrical conductivity, melting point, percentage elongation, hardness and drawability. All of these properties give the metals their unique characteristics and uses.
Whether you manufacture plane parts or bike frames, 7075 aluminum is a vital resource for your industry. An in-depth market understanding of this aluminum alloy allows you to discover the best prices and follow industry trends. HARBOR Aluminum Intelligence specializes in aluminum pricing and forecasting, giving you detailed insights that help you navigate the industry. Stay current on aluminum data within your industry by subscribing to market intelligence reports.
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