Steel Dominance Fading in Future Auto Bodies

TROY, MI – After successfully fighting off lighter alternative materials for more than a half century, steel is facing a losing a battle of attrition as future vehicle bodies are designed to be lighter and more fuel-efficient – at least at Honda.

“Based on our current understanding, we believe we’re approaching the practical limits of the application of high-strength steels,” says Frank Paluch, senior vice president at Honda R&D Americas at the International Automotive Body Congress here.

Honda industry leader in advanced high-strength steel use.

Steel makers have acknowledged they will lose more hood and decklid applications to auto maker weight-reduction efforts, but this may be the first time an auto maker has stated publicly it is planning to start phasing out some steel in vehicle bodies.

The revelation is especially significant coming from Honda, because the Japanese auto maker has been an industry leader in the use of advanced high-strength steels in high-volume mainstream vehicles.

However, Honda also has been on the cutting-edge of other materials as well, introducing the all-aluminum Acura NSX sports car in 1990.

Other auto makers may not be looking at phasing out advanced high-strength steels as aggressively as Honda, which does not produce full-size pickup trucks and SUVs.

A Ducker Worldwide study released in September says the per-vehicle content of advanced high-strength steels will increase 250 lbs. (113 kg) by 2025. Because AHSS steel grades can be made thinner, and thus lighter, than lower-strength grades, the increase will contribute to an average weight reduction approaching 80 lbs. (36 kg) per vehicle, Ducker says.

However, another Ducker study also predicts per-vehicle aluminum content will double by 2025. And there are reports that some auto makers are discussing full aluminum-bodied trucks.

Paluch will not give details on how steel will be replaced in future cars and trucks, but he says there is a specific timeline for the next 14 years. “We believe we’re pushing up against the limit (with steel),” he says in an interview on the conference sidelines.

“We have a very clear road map to 2025 on how we’re going to mature our body technologies and we believe we will introduce our technological advances methodically,” Paluch says. Honda typically makes major engineering changes each new product cycle, or about every four years.

“We’re a global company. We can’t just change overnight, but we have a very clear roadmap to 2025.”

Steel’s demise has been predicted many times in the past. In the 1980s and 1990s, plastic body panels were expected to replace steel because they did not rust or dent and facilitated quick styling changes. Composite pickup-truck boxes also were forecast to replace steel because they were lighter and more durable.

Steel makers answered with rust-resistant and dent-resistant products that were lower-cost and easier to form into parts. Then they answered with higher and higher strength alloys that could be fabricated into lighter-weight vehicle bodies and structural components.

And composite pickup truck boxes did not catch on because dealers could make more money selling plastic bed liners.

But a growing number of engineers now say it will be increasingly difficult or impossible to meet future fuel-efficiency and European carbon-dioxide emissions requirements with vehicle bodies made from steel.

Aluminum, magnesium, carbon-fiber composites and advanced plastics are being eyed as replacements for steel structures in optimized vehicle bodies. However, Paluch says steel is not going to disappear, it only will become less dominant than today. Steel currently comprises 55% to 65% of the weight of a typical light vehicle.

“It’s going to be a multi-material body,” Paluch says of future vehicle bodies.

– with Eric Mayne

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