Advanced High-Strength Steels and Design Optimization to Produce Efficient Vehicles

Interview conducted by Stuart MilneAug 8 2016

Russ Balzer, WorldAutoSteel Technical Director, talks to AZoM about the CO₂ emissions surrounding automotive vehicle manufacturing and the benefits of using Advanced High-Strength Steels and design optimization to produce efficient vehicles.

The steel industry supplies many different manufacturing sectors. Where do WorldAutoSteel fit in to this?

WorldAutoSteel is the automotive group of the World Steel Association and represents 21 of the world’s sheet steel makers. Together, they supply a great deal of the automotive steel in the world today. WorldAutoSteel does not market or sell steel; rather our members have come together in an unprecedented pre-competitive collaboration to demonstrate and communicate the benefits of using Advanced High-Strength Steels in automotive applications.

CO₂e emissions are becoming increasingly high profile in all industry sectors. Why is it so important that the automotive industry considers these during their manufacturing processes?

Emissions are produced at every phase of a vehicle’s lifetime. Consider that drawing raw ore out of the ground, processing that ore into usable material for automotive, creating vehicle components and putting it all together to make a vehicle, and recycling it after it’s useful life all produce their own set of emissions.  Right now, the regulatory framework is set up to only concentrate on the emissions that are produced during the burning of fuel during the vehicle’s useful life, called use phase or tailpipe emissions. Efforts are concentrated in achieving those regulations. This can lead to unintended consequences of actually increasing or shifting the emissions to another phase of the life cycle by incorporating production phase Greenhouse gas (GHG)-intensive solutions to achieve the use phase regulation. For instance, the figure below shows what is happening right now as vehicles switch to alternative powertrains.

Last fall WorldAutoSteel conducted a New Paradigm for Automotive Mass Benchmarking study. What was the main objective of the study and what were the major findings in relation to CO₂e emissions?

This study was conducted to provide insights into the current state of lightweight in production model vehicles.

The study, conducted by EDAG International, Inc., uses the A2Mac1 vehicle tear-down database of approximately 200 vehicles along with a benchmarking methodology. The methodology uses statistical regression analysis to isolate mass-efficient designs and compare lightweight, as presented in a paper by Dr. Donald Malen, University of Michigan, and Jason Hughes, A2MAC1 Automotive Benchmarking at the Society of Automotive Engineering World Congress in April 2015. A component structure that is identified as efficient is one that stands out statistically as much lighter than others of its kind of the same size, structural performance and material. For efficient steel, this could be due to the use of Advanced High-Strength Steels and/or because of a fully optimized design.

According to Malen, statistical benchmarking opens a whole database of today’s vehicles to the benchmarking process. With it, engineers can identify better, more realistic targets, saving time and money.

The study results were surprising to us. It uncovered a wide variation in efficiency among steel components in vehicles on the road today. Some are very efficient, and some are very heavy, comparing the same size and functionality. It further revealed that when aluminum closure components, such as doors, bumpers, hatchbacks, and decklids, are compared to efficient steel components of similar size, the 40 percent mass savings currently accepted as a standard measure of aluminum lightweight capability is not nearly reached. The study also showed that while use of aluminum may achieve mass savings at the component level, that mass savings is lost when an entire system is measured.

Using data and mass estimation models from the initial study, we next investigated the life cycle GHG impact of three principal categories of material usage in the Body Structure subsystems that were represented in the vehicle benchmarking data (provided by A2Mac1, a global benchmarking company.) The following are the three categories of material usage we examined in the A/B-Class vehicles in the database:

1. An average steel design;
2. An efficient steel design based on 17 of the most efficient body structures in the database;
3. An efficient aluminum design, which was derived from the most efficient aluminum structures.

The results of the LCA case study show that the aluminum body structure, though lighter, will result in a +1% increase in GHG emissions over its total life cycle. The steel body structure would result in a -1% decrease in GHG emissions.

What is Life Cycle Assessment and why is it so important?

Life Cycle Assessment (LCA) is a methodology that considers a vehicle’s entire life cycle, from the manufacturing phase (including material production and vehicle assembly) through the use phase (including production and combustion of fuel) to the end of life (EOL) phase (including end of life disposal and recycling).

Current automotive emissions regulations around the world are aimed at reducing GHG emissions of automobiles, but focus only on tailpipe emissions, which are only a part of the actual life-cycle impact of an automobile (See the figure). Emphasis on the tailpipe alone may have the unintended consequence of increasing GHG emissions during the vehicle life. For example, many automakers, in order to comply with increasingly stringent tailpipe emissions regulations, are turning to low-density materials in an effort to reduce mass. By reducing the mass of a vehicle, it is possible to reduce the fuel consumption and, consequently, the tailpipe emissions.

However, many of these materials can have impacts in the other life cycle phasethat outweigh any advantage that may be gained in the use phase. This means that, contrary to the stated objective of reducing the GHG emissions of automobiles, tailpipe-only regulations may have the unintended consequence of actually increasing the GHG impact. This is why WorldAutoSteel is participating in the development of LCA tools and methodology and encouraging the use of LCA in the formulation and implementation of automotive emissions regulations around the world.

What is the impact of choosing aluminium over efficient steels for automotive manufactures?

Even though current regulations do not capture these potential unintended consequences, there is still an impact for automakers. It’s about cost. As the benchmarking study showed, it is possible to achieve significant lightweighting with steel and design optimization. For instance, an efficient steel bumper in the database, which are vehicles currently on the road, achieves nearly the same mass as the aluminium bumper.

We aren’t sure because the database does not provide material chemistries, but we can only assume that this kind of efficiency was achieved with design optimization and higher strength steels. We see this as hands-down evidence of steel’s yet untapped potential. The grades available today and being developed for tomorrow are up to the task, and at less cost than aluminium, both in terms of material purchase and the cost of retooling a manufacturing facility to handle it.

What does 1% Kg/CO₂e mean in real terms?

One Percent doesn’t seem like much. But consider this—if 6 million of the compact cars (the vehicle class in the auto mass benchmarking LCA study) were converted to aluminium, you would need to turn Tokyo’s 824.5 square miles, which houses the highest capital city population in the world, into a forest in order to sequester the resulting additional CO₂e that would be added to the environment.

And the vehicle would cost a great deal more, which is why you don’t see aluminium compact class vehicles. I think this begs to ask the question: is it worth it?

If the overall all CO₂ emissions are lower for manufacturers using efficient steel, why are some automotive manufactures choosing aluminium instead?

Automakers are being forced to make tough decisions in order to achieve the very stringent CO2 emissions requirements on their vehicles. And they are getting tougher with each regulatory iteration (see Figure).

They are trying to find the silver bullets that will help them achieve the fleet averages they must meet.  So they are exploring low density lightweighting materials, as well as other technologies such as alternative powertrains. And all this while trying to meet consumer demand for more and more vehicle content. But be assured that the steel industry is doing its best not only to demonstrate AHSS use, but to make grades commercially available to supply the global market.

According to a 2014 Ducker Study, AHSS demand would double by 2025. That demand has already proven to be 10% higher than predicted. And the evidence is in the fact that automakers are talking about the use of Advanced High-Strength Steels in their new vehicles. We track this and can hardly keep up with the announcements and claims of automakers who have achieved significant mass reduction through new vehicle redesigns primarily using AHSS technology. See this on our website: http://www.worldautosteel.org/why-steel/steel-muscle-in-new-vehicles/

How do you see the industry developing in the future?

Many automakers are already using life cycle assessment as part of their vehicle product development process. They are using it to achieve environmental efficiencies. We believe that a regulation that gives them the freedom to look at the whole vehicle life cycle will result in a better outcome for the planet. And because of that, we are working with regulators and academics to help find options that will be real solutions toward that end.

Where can our readers learn more about the impact this is having on global CO₂ emissions?

We have a great many resources on our website on Life Cycle Thinking, which you can find at www.worldautosteel.org. From videos and infographics to technical case studies, you can learn a lot about the advantages of using vehicle life cycle assessment.

About Russ Balzer

Since 2012, Russ has served as Technical Director for WorldAutoSteel, a global consortium of steel producers serving the automotive market. As Technical Director, Russ manages a variety of engineering projects, and has tactical and strategic responsibilities in WorldAutoSteel’s efforts to use and promote Life Cycle Assessment (LCA.) In this role, Russ acts as the WorldAutoSteel delegate to the World Steel Association LCA Expert Group.