In June 1919, 100 years ago, the Junkers F.13 made its first successful flight. This first all-metal airliner in human history uses 2017-T4 aluminum alloy (Al-4Cu-0.5Mg) as the body material. The common aircraft aluminum alloy 2024 is based on 2017 with the addition of magnesium Mg. 7xxx aluminum 7075 added zinc Zn on the basis of 2024, and adjusted the content of Mg and Cu.
The first stage is from around the 1920s to the 1960s. The 2000 series aluminum alloys made all-metal aircraft mainstream, and 7000 series aluminum represented by the early 7075 made it possible for airliners flying in the stratosphere. Representative models are DC-3, B-29 and 707.
he second stage is from the 1960s to the mid-1990s. A series of new 7-series aluminum alloys such as 7150, 7050 and 7055 have been developed to improve the specific strength while taking into account the fatigue characteristics. Representative models are A300 series.
The third-generation aluminum alloy is represented by aluminum-lithium alloy, which is adopted by more and more newly developed models. Representatives include A380, C series (now A220) and C919.
The start of World War II accelerated the evolution of materials. The B-29, which has an airtight cabin, used 7075 ultra-high-strength aluminum alloy for the first time. Compared with 2024, its specific strength has increased by almost 50%, but it has a similar specific modulus.
The 777 currently in service uses aluminum alloy as the main material, and is a master of the second generation of aluminum alloy materials. It should also be the last wide-body civil aviation airliner with aluminum alloy as the main material.
The third-generation aluminum-lithium alloy can achieve the balance of strength and hardness, low density (weight reduction), corrosion resistance, fatigue resistance, thermal stability and other properties through optimization of chemical composition and heat treatment. It can be widely used in wing and fuselage structures. The aircraft aluminum thickness also become thinner than before.
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