(Q&A) The evolution of metals and automotive materials | foundry-planet.com
Mining company Rio Tinto began building the world’s largest scandium oxide plant in Canada in January, renewing the global focus on potential applications of scandium in lightweight aluminum alloys.
Argus spoke with David Weiss, vice president of research and development at Eck Industries, a US producer of premium aluminum castings, to discuss why and how structural materials are changing.
The modified highlights are as follows:
A passenger car has tens of thousands of parts and a commercial aircraft has millions. The materials used are constantly evolving, what is the most important factor of change?
Energy efficiency – for 20, 30, 40 years, this has been the same primary factor for automotive and aerospace. In the 60s and 70s cars were made with a lot of iron. They worked fine but they were heavy and when fuel prices went up they had to change. Weight is even more important in aerospace and they were the first to adopt aluminum planes – but fuel prices had an impact there as well.
We now have a new challenge, the environmental footprint. The lighter you are, the less fuel you consume and therefore the less emissions you produce. For electric vehicles (EVs), the problem is quite different: the batteries are heavy. The weight of the total power pack in an electric vehicle is heavier than the engine of a gasoline or diesel car. All this gives new impetus to the desire to reduce the weight of vehicles and find new materials.
How do material changes occur?
Imagine you are a design engineer and your boss’s boss said, “We need to take 500 pounds out of this vehicle.” This triggers many meetings to find out what are the elements where this could be easily achieved. Then you go through a reduction exercise to see which components would give you the most weight reduction relative to the cost. A good example is when Ford decided to install aluminum truck beds on all of its F150 vans. A truck bed is heavy, so the decision to do so means that everywhere else it can be made lighter. And once they start working on the new design, they can see some gaps in the material they have chosen. First, they will look at common alloys to see if they would be suitable for the design. If these don’t work, they go to a person like me and say, alloy me. They might ask for more resistance at a certain temperature, slightly stiffer or stronger at room temperature or whatever is needed.
I was recently at a meeting at an auto company where in a previous meeting they had placed post-its on the table indicating how much weight we could save if we made this conversion and what it would cost. Sometimes you can grab a material that doesn’t cost more or maybe replace a plastic with metal. You choose the easiest and work your way uphill. You are always looking for the cheapest way to save weight. Automakers will only go as far as they need to, which is why the government’s corporate average fuel consumption (CAFE) regulations are so important. Finding the most economically efficient way to meet CAFE requirements is a really complex endeavor. Cost and performance are two opposing sides of the coin.
What types of materials do cars use?
Steels and irons have long been the basic material and there are hundreds of different variations. As more materials have come to call the automotive industry, they have improved a lot. There are now very high strength steels that make it possible to manufacture much finer steels. And there is as much R&D in steel space and iron space as in other materials. The other dominant material is aluminum. It has been in commercial applications for 125 years and some of the very first applications of aluminum were in automobiles. Aluminum is still a growing player and people like me continue to work on the development of new alloys.
The other one that is coming but which is most widely used in the aerospace industry is titanium. Titanium is stronger than steel or aluminum, but it is also much more expensive. It grows more slowly but is used more in parts prone to fatigue like connecting rods. The other material that has appeared are carbon composites. Composites are lighter in weight and have some of the properties that many applications require. But they are very expensive to manufacture. Much work continues to be done to reduce manufacturing costs.
Magnesium is a good story. We have been working with him for several years. It is about two-thirds the weight of aluminum, and many alloys are almost as strong. But the metal is much more expensive, and there are lingering concerns about the safety of the manufacturing process itself rather than the magnesium in the final vehicle. It is most widely produced in high pressure die casting, like elevator gates or dashboards.
Is it a race between materials?
There will be no clear winner or loser. We believe we are in a race with each other, but it is a matter of degree. You want to recover as many apps as you can. Everyone is trying to increase their market share through their own innovations and cost reductions. One of the buzzwords in the automotive industry is multi-material structures. To use each material most effectively, you need to be very aware of what you are attaching it to or you may have unwanted interactions. I am absolutely neutral on the entire periodic table. The periodic table is the toolbox.
Scandium is another important tool that can be used to produce better alloys, especially better aluminum alloys. There is currently a lot of work in progress which I am very happy with. Rio Tinto really brings its reputation to scandium and the supply base is now considered reliable. There are specific applications that will gain enormous benefit, probably initially in aerospace with satellites as an example. One potential area is what we call the techno-economic divide between titanium and aluminum. Say you need light weight or better high temperature performance and material just 10pc stronger than best aluminum alloy. If you can’t redraw the part, you might have to use titanium, which is considerably more expensive. In this case, you can pay 10 times more for just 10% improvement. Scandium is one material that could help close this gap.
Can a vehicle be too light?
Not really, but there are specific applications where this can be a problem. An example of this is the transition from rear wheel drive cars to front wheel drive cars. If you make the rear of the car too light there will be a fishtail on you so this is a case where we were doing a conversion and couldn’t use a lighter material. There are specific types of vehicles like earthmovers and tractors where you cannot make them light because you are trying to lift things. But in general, if you meet the mechanical requirements of what’s required, you can’t be too light.
There is also a secondary benefit that is less emphasized: performance. When you reduce the weight of a vehicle, it becomes more agile, performance improves. There are areas where this is critical, such as in the racing industry, which are early adopters and very creative when it comes to trying out new materials, and in the defense industry. .
Tell us about the early adopters?
If you think of it as a risk curve, auto racing is really in the lead. If they see a good idea, they will take it and start experimenting. They can face a steep learning curve and expect things to break down. If your race car breaks down, you can just stop and fix it and learn from it. Better performance translates into money and they can test and accept new material in just one year.
The defense sector sits somewhere in the middle of the risk spectrum. Nothing is ever good enough and they are always on the lookout for new materials. It is really interesting work. Their guiding light improves survivability. New ideas from the metallurgical industry find their way more easily into the defense industry. They want to hear everything that is going on. They want soldiers to be better protected and they want better mobility and that goes beyond simple commercial considerations. According to them, we must be the best. It creates a lot of space for innovation.
When a new high-strength aluminum-copper alloy first appeared in the 1970s, we worked with the US Army Tank Automotive Command for six years to develop the techniques necessary to produce complex structural castings and solve all of the problems. problems which had made the work difficult. and prone to faults if handled improperly. This A206 alloy was widely adopted in the Bradley Fighting Vehicle in the 1980s and is now widely used for applications such as gearboxes and suspension components. And we remain the leading producer of castings from this alloy.
Since 2015, we have been working with US national laboratories and commercial customers on an aluminum-cerium alloy program. The program is supported by the US Institute of Critical Materials at the Department of Energy. These alloys have very good properties at high temperatures and superb corrosion performance. These alloys are used in hydropower, pumps, turbochargers and cylinder heads. They have been on the market for two years and are constantly evolving.
Have you ever said “no, it’s impossible”?
No, it’s just a matter of your time and resources.
Source: Caroline Messecar (Argus Media group.)