June 26, 2013 Pound-for-Pound

Volume 16 | Issue 5

The boundless heavyweight fight continues between steel and aluminum for supreme lightweight bragging rights for automotive body structures.

Aluminum’s greatest strength in its ongoing war against its steel counterparts is losing its luster.

At least that is what the steel industry is suggesting after a new set of research studies show that aluminum is no longer the be-all of necessary lightweight material for automotive body structures.

In fact, according to WorldAutoSteel, the automotive group of the World Steel Association, steel auto body structures in the near future will likely be on par with today’s aluminum bodies. Likewise, it will meet all crash performance standards at a comparable cost of current steel structures.

The studies also address critical manufacturing challenges, showing that auto manufacturers can form and fabricate sophisticated steel designs. That is promising news for carmakers worldwide seeking an alternative to aluminum – more expensive but also two-thirds of the weight of conventional steel – to shed automobile weight to meet new emissions standards.

“I think often times there is an impression that in the automotive market, we must go to low-density materials instead of steel, essentially replacing steel in order to achieve vehicle lightweighting,” Edward Opbroek, Advisor at WorldAutoSteel, tells Industry Today. “We do not agree.”

He adds, “It is not a matter of using or making lightweight material in a car. It is a matter of making a lightweight car. You can do that very well with advanced high-strength steels and optimization of the design.”

Good thing, too, he says, with automakers using lighter-weight material to improve gas mileage and meet the U.S. government’s Corporate Average Fuel Economy goal of 54.5 miles per gallon by 2025. In general, fuel economy rises by at least 3 to 4 percent when the vehicle’s mass is reduced by 10 percent.

That originally posed a threat to steel. Not anymore, Opbroek says.

A DIFFERENT STEEL
Because aluminum has steadily taken away market share from steel – usage, it has been reported, tripled in North American and Europeans vehicles over the past three decades – it has long been presumed that the demise of steel was nearing.

Keep waiting, says Opbroek, adding, “we think, the future is very bright” for steel.

“The number of cars built during the worldwide recession was lower; therefore, a lower amount of steel was used,” he explains. “But that’s now coming back. If you measure the percentage of steel used per vehicle, that amount has remained constant for a number of years.”

To clarify, that percentage is nearly 60 percent of a typical car’s weight, he says. Aluminum, meanwhile, makes approximately 8 percent. Moreover, one of every eight tonnes produced by the global steel industry goes into automobiles.

Another developing strength is that the industry has developed a lighter-weight, high-strength steel that helps automakers boost fuel economy and reduce mass by up to 39 percent, compared to a baseline steel body structure carrying an internal combustion engine. Those figures, WorldAutoSteel reports, are adjusted for a battery-electric powertrain and year 2020 regulatory requirements.

The optimized body, association officials say, would weigh just 176.8 kg, putting steel on par with today’s aluminum production designs. An industry database of current production vehicles shows these lightweight, advanced high-strength steel body structures, designed to carry heavier electrified power trains, fall in line with the lightest internal-combustion-engine aluminum vehicles, and are on par with other concepts featuring multi-material solutions.

Studies show that by incorporating technology, developed via WorldAutoSteel’s FutureSteelVehicle program, automotive manufacturers can keep away from more pricey alternatives involving competing materials and multi-material designs to achieve their goals.

“Our latest light-weighting projects show the continuing potential of steel and demonstrate how car makers can take advantage of steel’s design flexibility and use Advanced High-Strength Steels (AHSS) to meet their difficult challenges for improving fuel economy and reducing greenhouse gas emissions,” said Cees ten Broek, director, WorldAutoSteel.

He adds that steel’s design flexibility enables the best use of the award-winning, state-of-the-future design optimization process that better develops non-intuitive solutions for structural performance. The final optimized shapes and component configurations, he suggests, often mimic Mother Nature’s own design proficiency, allowing engineers to place specific materials in the structure to meet structural and strength requirements for managing vehicle loads.

USE LESS – BUT BETTER – STEEL
Opbroek, meanwhile, suggests that the greater steel industry has developed a somewhat unusual marketing campaign of late: “Please, we ask, use less of our products.”

That is because while vehicle manufacturers may eventually use less steel per vehicle, the steel they will use will be of a much higher value.

“We are deliberately trying to reduce the amount of steel used per car as we reinvent steel along the way, going from the former conventional steels to the advanced high-strength steels,” he says. “We have dramatically moved from conventional steels to high-strength steels and advanced high-strength steels. Today, over 50 percent of steel used in automotive bodies include some form of advanced high-strength steel.”

A number of manufacturers have already followed suit, he says. The use of high strength steel in North America has reportedly doubled between 2005 and 2009 to 150 pounds per vehicle. Usage, he says, may double to 365 pounds by 2025.

He adds that cutting vehicle weight with advanced high-strength steel can be accomplished at no total system cost penalty, while using aluminum costs four times as much.

ABOUT WORLDAUTOSTEEL
WorldAutoSteel, the automotive group of the World Steel Association, is comprised of 18 major global steel producers from around the world. Its mission is to advance and communicate steel’s unique ability to meet the automotive industry’s needs and challenges in a sustainable and environmentally responsible way. It is also committed to a low carbon future, the principles of which are embedded in our continuous research, manufacturing processes, and ultimately, in the advancement of automotive steel products, for the benefit of society and future generations.

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