Titanium Grade 9’s exceptional blend of lightness and tremendous fatigue resistance makes it ideal for the production of more sustainable aircraft. As a key end-to-end producer of Ti Grade 9 tubing, Alleima helps the aerospace industry cut carbon emissions and improve fuel efficiency.
While the world waits for electric and hydrogen-powered commercial airplanes, its best chance for sustainable air travel is to make aircraft as fuel-efficient as possible.
However, the total fuel consumption of global commercial airlines began rising again in 2021 after a brief drop during the pandemic and was forecast to reach 302 billion liters in 20231 (source: Statista). In some parts of the world, such as the European Union, new laws and targets are challenging the aerospace sector to find ways to slash carbon emissions.
The best approach for producing planes that use less fuel, reduce emissions, and fly efficiently is to make them lighter. However developing cost-effective, sustainable materials with better strength-to-weight ratios is a constant challenge. Lighter aircraft must be strong enough to safely withstand extreme temperature swings during flights at great heights and speeds.
With its extraordinary combination of high strength and low density, Titanium Grade 9 satisfies the demands for structural integrity under pressure while still helping to keep the weight of the aircraft down.
And at a time of increasing geopolitical uncertainty, Alleima’s end-to-end, fully integrated production capability between its sites in Sandviken, Sweden, and Kennewick, USA, makes it a key producer of this alloy for most of the big aircraft OEMs; especially for the tubing that contains the hydraulic lines which transport the force that moves airplane actuators, tails and wings.
“Aerospace is the biggest factor in titanium’s sales growth,” says Inger Fjällström, Sales Engineer for Special Metals at Alleima, a key global producer of Ti Grade 9 and other alloys. “Titanium Grade 9 is a lightweight material but it has greater strength because it’s alloyed with 3% aluminum and 2.5% vanadium.”
Three particular advantages of using Ti Grade 9 for hydraulics tubing are its fatigue resistance, insulating capabilities and ability to withstand corrosion.
“Flights start at ground air temperature, then after take-off they quickly reach heights of more than 30,000 feet (10km), where the outside air temperature sinks to -minus 50°C,” says Guirec Guyon, Global Industry Manager Aerospace at Alleima.
“The Titanium Grade 9 tubing will keep its mechanical properties even at this very low temperature, allowing the hydraulic lines to perform as expected during the flight.” Like other parts of an airplane, the tubing also has to be fatigue-resistant to withstand cyclic loading: repeated, systematic stresses on the same area.
Then there are the highly corrosive fluids used in the hydraulic lines that the tubes carry. “Before I joined Alleima I had a background in the lubricant business, and the fluids used for hydraulic lines are some of the most corrosive ones that I’ve seen. There are specific safety handling measures that every operator who deals with it must follow,” says Guirec Guyon.
He adds that it takes a couple of hundred thousand pressure impulse fatigue test cycles to qualify the tubing, taking place at different temperatures so as to over-stress the material and ensure perfect performance of the tubing in actual flight conditions.
“Ti Grade 9 has been used for several decades by most of the big aircraft OEMs and it will continue to be used for some time to come. The alternative would mean a lot of testing of new material, with long re-qualification processes from the aviation authorities around the world. That’s time-consuming and expensive and the industry prefers to avoid that if it can,” says Guyon.
Greater fatigue and corrosion resistance also give the tubing a longer service life with less maintenance required. That’s good news for safety and operational cost efficiency, due to less aircraft downtime.
The need for very tight tolerances, perfect dimensions and achieving the right force and texture in the material make Titanium Grade 9 challenging to produce. But Alleima has decades of experience with a secure and established complete production process, from the initial titanium sponge through to the finished tubing.
“We’ve mastered the difficult art of producing Ti Grade 9, which is trusted by some of the biggest players in the aerospace industry because it withstands the demands of hundreds of thousands of hours of tests and performs under the most challenging temperatures and corrosive conditions,” says Guyon.
“We are working together with our customers to make innovative changes. Our advanced metals and alloys help increase efficiency and reduce energy consumption,” adds Inger Fjällström.
“The market trend for aerospace is increasing and after the problems of the pandemic, the industry is expected to reach its 2019 levels by late 2024. We at Alleima and Titanium Grade 9 have an important role to play in helping the industry achieve a sustainable future.”