The electric vehicle (EV) revolution is not just about changing the way cars and trucks are powered. It’s also a complete rethink of how they are designed and built. As with other pivotal moments in the evolution of human transportation, such upheaval has prompted speculation about other light-weight materials like aluminium or carbon-fibre ousting steel from its leading role in vehicle superstructures. Indeed, in the pursuit of energy efficiency, ultra-lightweight is alluring. However, at ArcelorMittal, the world’s leading supplier of steel to the auto sector, we remain fully confident that steel will continue to outperform – as it has for decades - on the combined basis of cost, safety and weight reduction.

If humans are going to decarbonise mass personal transport, electric vehicles are the only option. Typically, 15% of an internal combustion engine’s (ICE) carbon footprint is in its manufacturing and 15% in its end-of-life; the remaining 70% derives from the emissions generated during its lifetime by burning petrol or diesel. As long as electricity grids are powered by renewable sources, EVs are thus the logical way to reduce the CO2 produced from mass personal transport. 

This, of course, presents many challenges to the vehicle manufacturers, not the least of which is building EVs that are safe and affordable for mass-market adoption. Steel is the clear answer all these challenges and I’d like to explain why. 

Despite all the gains in traffic management technology, there is sadly no such thing as a crash-free world. Furthermore, the average EV weighs more than a petrol- or diesel-powered alternative – basically, batteries are heavier than engine blocks. This means they have more kinetic energy going in a crash. To keep passengers safe and secure, vehicles must therefore have greater body strength to absorb and deal with the energy from an impact. As such, in an EV-dominated world, stronger and more energy absorbent materials like steel will become even more important.

But it is not simply the inherent strength of steel that wins here. It’s the constant reinvention of what we do with the material that really makes the difference. Other materials lag far behind in advancements.

For example, our ArcelorMittal Multi Part Integration™ (MPI) concept radically simplifies the production process by reducing the number of sub-parts needed for the same application. With a MPI double door ring for example, we can reduce the part count from 13 to 2, leading to 33% savings in hours of labour per module in the assembly shop. On top of simplification, by optimising the nesting of parts, we can increase the material utilisation rate by 5% for the inner ring and 4% for the outer part and improve the overall body structure. Overall, that means the amount of steel required in a MPI double door ring, when also utilising the latest generation of press hardened steels, can be reduced by 22 kilograms. This means an 11% reduction in the weight of the double door ring.

Another example is with the battery enclosures. Batteries are often packed away under the floor, taking up the area beneath the seating. Real estate in the vehicle underbody is critical, as saving space here means more room to add additional battery cells to increase driving range. By developing multi-phase steels with higher tensile strength, we have enabled battery enclosures that are tighter in the corners and fit in a smaller packaged space, creating more space for additional cells that support longer range.

Fully autonomous driving systems – whereby most people don’t own their vehicle and instead get about by simply hopping on and off a vehicle summoned via an app – remain a long way off. That means that for decarbonisation to occur manufacturers must make vehicles that are of an acceptable cost for widespread, mass-market adoption. This is another area where steel commands strength.

In the 2010s, in response to increasing pressure on auto-manufacturers for fuel efficiency, there was lots of speculation about aluminium replacing steel because of its reduced weight, and Ford did indeed shift from steel to aluminium in the early part of that decade with their flagship F-150 truck. However, the steel industry responded with a suite of innovations and technological improvements to produce an ultralight steel auto body that came so close in weight to aluminium that the increased cost of the latter made no commercial sense. Consequently, steel intensive structures remained dominant for large SUVs and pick-up trucks.

At ArcelorMittal, we housed our innovations under the S-in motion^® brand name, which is a set of steel solutions that help carmakers make their vehicles lighter, safer, and more environmentally friendly. Electrification has placed new challenges on car designs, with enhanced crash performance required due to the increased weight of the car, and also a need to protect the battery during an accident. In recent years we have therefore expanded our S-in motion^® solutions to cover EVs, so that we can support auto OEMs on their electrification journey. Our solutions cover cars from B-segment to SUV EVs, with our offering including chassis and battery pack solutions. These solutions, which incorporate our latest advanced high strength steels, have demonstrated a highly competitive performance in terms of weight, at a much lower cost and with lower CO2 emissions when compared with alternative materials.

Another important cost-related consideration in the switch from ICEs to EVs is the opportunity for manufacturers to completely overhaul their production lines, often with entirely new plants and facilities. As well as being the top supplier to the auto industry, ArcelorMittal is consistently ranked number one in technology by the majority of global automakers. This is because of our close collaboration with them. We’re not simply a steel supplier. We are a steel solutions provider, working with the automakers to produce exactly what they need – our steel engineers are embedded within auto-manufacturer teams in markets across the world.

That means we’re deeply involved with the automakers as they design the vehicles and associated production lines of the future. Now, cutting edge production lines are deploying continuous laser-welding of multi-part blanks, hot-stamped on site, resulting in shorter and lower cost assembly lines. Not only is this ‘modular approach’ cheaper in terms of labour or investment in robots, a reduction in the number of welded joints can increase the strength of a vehicle structure significantly.

The pace of change has been staggering - before 2015, we produced fewer than half a million multi-part integrated blanks every year. Next year, that total is likely to be over 30 million globally – and we reckon this business will continue to grow at 10%-15% or more for years beyond that.

Another interesting aspect is where the demand is growing. Some of the fastest adopters of these latest technologies are the Chinese manufacturers. We have been amazed by their demand for the most advanced steel technologies and the speed at which they have adopted them. There is a very deep-seated realisation that vehicles designed around a hot-stamped steel structure are without doubt the safest vehicles on the road.

Our standing as the world’s leading materials supplier to the automotive sector has been hard earned. Ensuring we retain this position will involve continued product innovation and investment in our production capabilities, particularly to support the transition to EVs and enhance our electric steels production capabilities. We’re committed to both priorities and convinced that steel has all the credentials required to remain the material of choice that fuels the electric vehicle revolution.