On August 1, 2022, COMAC announced that the Chinese-made large aircraft C919 has completed the certification test flight, less than 10 days have passed since the completion of all test flight tasks previously announced. The successful test flight also means that the C919 delivery operation has entered the countdown.
Among them, a variety of advanced materials have been widely used in C919, including the first large-scale application of third-generation aluminum-lithium alloys in civil aircraft, and the first use of T800 carbon fiber composite materials in Chinese civil aircraft.
Aluminum Lithium Alloy
Aluminum alloy is one of the most critical materials for civil aircraft manufacturing. On the C919 aircraft, aluminum alloy accounts for 65% of the total weight of the entire aircraft structure, including the front fuselage, middle fuselage, middle and rear fuselage, nose and wing structural parts, etc. All use aluminum alloy materials.
It is worth noting that on the C919 aircraft, China used the third-generation aluminum-lithium alloy on a large scale for the first time, and its proportion of aluminum in the whole aircraft has reached 8.8%, surpassing the Boeing 737 and Airbus 320 aircraft of the same level, helping the C919. Overall weight loss of 7%.
In terms of performance, aluminum-lithium alloys have the characteristics of low density, high strength and excellent damage tolerance. The use of aluminum-lithium alloys can reduce the quality of aircraft aluminum alloy parts by 14% to 30%, thereby reducing the annual cost of each aircraft. The flight cost has dropped by more than 2.2%, so it is considered to be an ideal structural material for a new generation of aircraft.
Major breakthroughs have been made in the research and development of aluminum-lithium alloys, such as 2A97 and X2A66.
The high-performance aviation aluminum used in the C919 fuselage has been 100% localized, mainly provided by ZLXN Aluminum and SDNS Aluminum.
Titanium alloy
Titanium alloy has the advantages of light weight, high strength and good corrosion resistance, and is widely used in the aerospace field. It is known as "space metal". parts, joint fasteners, etc.
The main listed companies of titanium alloy products are SXBT, SXCD and SXXB. Among them, SXBT is a titanium alloy material supplier of COMAC, and is the largest titanium and titanium alloy production and scientific research base in China; SXCD titanium alloy products are concentrated in the application market, mainly in aerospace and other military industries.
Ultra High Strength Steel
Ultra-high-strength steel is a high-strength and high-toughness alloy steel developed on the basis of alloy structural steel. It is an important material in the field of national defense and military industry, and is widely used in rocket engine casings, aircraft landing gear and other fields.
Chinese enterprises are represented by SHBG and LNWS Special Steel, and SHBG Special Steel and LNFS Shun Special Steel are the steel suppliers of COMAC. Among them, the ultra-high-strength 300M steel trial-produced by SHBG Special Steel and LNFS Shun Special Steel meets the installation and use requirements of C919 aircraft, realizing the localization of ultra-high-strength steel.
T800 carbon fiber composite
In the application of C919, composite materials have also become one of the key materials, and its application has reached 12%, most of which are carbon fiber / epoxy resin composite materials; application parts include horizontal tail, vertical tail, winglets, rear aircraft key parts of the body.
In addition, the manufacture of C919 is also the first time that China has used such a large-scale composite material on a civil aircraft, and it is also the first time that China has used T800-grade high-strength carbon fiber composite materials on a civil aircraft. The agency pointed out that it is expected that C919 will bring an average annual demand of 300 tons of composite materials, of which the demand for local T800 carbon fiber will reach an annual average of 100 tons.
Most of the composite materials used in the C919 forensics machine are imported, and it is expected that the localization process will begin after the forensics are completed. Chinese carbon fiber manufacturers SDGW, JSHS, and JSZF all cooperate with COMAC and downstream parts manufacturers to varying degrees. SDGW participated in the PCD airworthiness certification of C919 and obtained pre-approval. For the application of CR929, material preparation is currently in progress; ZHGK has been selected as the only supplier of COMAC CR929 front fuselage work package.