While the concept of ‘future mobility’ is often presented as a transformation of the automotive industry, vehicle manufacturers are still building cars, and all of them are made primarily from metal. For material suppliers at the coalface of the industry, it is unclear how the move toward connected, autonomous, shared and electric vehicles (CASE) will affect their operations.
Swedish steel producer SSAB believes that the fundamentals of its business will remain largely unchanged. While it can be challenging to be heard among the noise of exciting new technologies in the cockpit and powertrain, advances in materials science behind the scenes are enabling automakers to continue hitting targets for safety, efficiency and performance.
Key trends hold true
“It is more or less business as usual,” explained Thomas Müller, Head of Automotive Business Development at SSAB. “The focus on materials is not as strong today, but it remains a highly relevant topic in relation to mobility and emissions reduction. That will require lighter vehicles, so while we are not the main focus for automakers today we are by no means forgotten.”
Innovation in materials science is also being driven by the need for reduced weight without compromising strength, and those considerations will not be off the table any time soon. Autonomous vehicles may promise a future of zero traffic collisions one day, but passengers in the meantime need to be kept safe in the event of a crash.
“Today’s crash requirements will remain critically important, at least in the short- and mid-term. That is a pretty strong reason to use advanced high strength steels (AHSS),” said Müller. “Even if a car can theoretically avoid all crashes in future, here in Sweden you often have to avoid a moose that runs out into the road—there will still be crashes to protect against.”
EVs
Another consideration is the need to reduce the ticket price of new vehicles, many of which will come with battery electric powertrains in coming years. The average price of an electric vehicle (EV) is significantly higher than a comparable gasoline or diesel model today, and the ability to bring that cost down will allow manufacturers to reach the mass market.
Indeed, automakers already tussle with slim profit margins, and when a large proportion of the vehicle’s cost stems from the body-in-white (BIW), the choice of material is a hot topic. The battle between steel and aluminium in particular has caught the headlines in recent years, and a push for mass-produced EVs has rekindled the debate.
While initial EV platforms would look to achieve the biggest weight savings possible, often through aluminium or in some cases more exotic carbon-fibre, it quickly became clear that such materials would not be sustainable for high volume vehicles. Consider Tesla’s decision to opt for a steel-intensive body for the Model 3 compared to the aluminium-intensive Model S and X; Volkswagen’s scalable MEB architecture, which is primarily steel-based; and the steel-intensive Nissan Leaf.
As a result, steel has steadily come back into the frame. “EVs are very expensive today, and for those that can afford them the extra cost from aluminium or carbon fibre is fine,” said Müller. “But as they become more available for the mass market, that additional cost really starts to matter. We can see a slow shift from aluminium and other exotic materials towards high strength steel as automakers face more cost pressure.”
There may be no combustion engine in an EV, but there is a heavy battery pack, which in some larger models can weigh as much as a grand piano. Cutting out weight elsewhere—a trend known as lightweighting—is just as critical for an EV manufacturer as it is for any diesel or gasoline vehicle. Savings made by using steel could also be reinvested in more advanced battery technology to bump up electric driving range.
Formability
The strength of AHSS has plateaued somewhat in recent years, but not due to technological constraints. Steel grades have simply become so strong that further improvements are surplus to requirements. Instead, producers have been innovating to make steels easier to work with without sacrificing any of that strength. This is not an easy feat.
“Unfortunately, formability and strength are contradictory characteristics,” explained Müller—a strong steel typically has low formability, and vice versa. “The trend now is not to make stronger steels, since the strength level is already very high at up to 2,000 megapascals,” he continued. “Today, the trend is to make gradual improvements to the level of formability while retaining that strength.”
Third-generation AHSS grades have made good ground here, but typically come with higher cost and the potential for difficulty when welding. There is still work to go, but these super strong steels could be used not only for the BIW, but also to replace more intricate lightweight components in future. “The big breakthrough for these steels has not come just yet,” Müller said, “but the trend is clear: retain strength and improve formability so the steel can be used in different places in the vehicle.”
Battery housings, for example, tend to use aluminium today, but could be replaced with AHSS in upcoming model cycles. Here, the housing plays a critical role in vehicle safety as it must protect the battery during the event of a crash.
Sustainability
SSAB has been working with Swedish mining company LKAB and state-owned power company Vattenfall as part of the HYBRIT project, which aims to produce fossil fuel free steel by replacing coal with hydrogen. Steel production creates a significant amount of CO2, and SSAB sees an opportunity to help automakers reduce what is known as ‘total life cycle emissions’—that is, the emissions created not only by the vehicle itself, but also those created during its manufacture.
SSAB has also investigated other ways to go green—quite literally in one instance. It has been trialling ‘green coal’ that is sourced from Sweden’s wealth of forests, which Müller believes would make sense in the short term. The steel industry, he says, can help vehicle manufacturers to achieve lower lifecycle emissions as part of the ‘future mobility’ transition. “We need to reduce green house gas from steel production much further, and it is certainly our long-term goal to be fossil free,” he explained.
No material change in sight
While the trends underpinning ‘future mobility’ may bring a raft of changes to automakers and consumers alike, the fundamentals of creating the skeleton of a vehicle will remain. Today, advanced thermoplastics are used for vehicle body panels and interior components, but it is unlikely that the BIW will ever stray from metal of some form.
“When it comes to parts that are subjected to high loads and structural elements, such as the BIW, metal is still probably the best you can get right now,” mused Müller. “You could technically build the whole thing in carbon fibre, but it would cost as much as an aircraft.”
For materials suppliers such as SSAB and indeed the rest of its peers in the steel and aluminium space, future mobility will not bring the disruption that has been felt elsewhere in the industry. Tweaks to the business will be required in order to cater to the introduction of electrified powertrains and changing vehicle designs, but steel suppliers appear to be sitting comfortably as it stands.
“There have been many changes taking place across the industry, but the main consideration—that cars need to be lighter and give protection in a crash—has not changed,” concluded Müller. “While materials suppliers may not be the key focus for automakers at the moment, we are at least still in second place.”
