Steel + Aluminium = Lighter Weight

Material substitution will play a critical role in meeting emissions and fuel economy targets, writes Abey Abraham, Project Director at Ducker Worldwide

As the countdown to 1 January 2025 continues its relentless march towards the United States mandated emissions (163 grams of CO2 per mile) and fuel economy (54.5mpg) targets, the decisions light vehicle OEMs have to make are no less agonising. The emissions and fuel economy targets that OEMs are faced with for any new light vehicle sold in the US impacts the global fabric of engineering, design and supply chain, and has engineers literally measuring weight savings not in pounds or kilos but in grams. It has undoubtedly increased the complexity and cost of introducing the next generation of vehicles to our driveways.

The OEMs have a plethora of options from which to choose in order to achieve the mandates, including the use of advanced low rolling resistant tyres to engine downsizing, such as replacing a big block V8 with a direct injected, turbo-charged, small displacement inline-4. OEMs are willing to evaluate anything that can help bridge the gap from today’s CO2 numbers to the required 163 grams of CO2 per mile. However, industry experts believe that it will be a balancing act between three main areas including vehicle weight, aerodynamics as well as powertrain efficiency improvements. Ultimately, what really sets one option apart from another is its cost-to-benefit ratio; how much it will cost the OEM to improve MPG or reduce CO2.


Ducker believes that by 2025, North American light vehicles will likely incorporate the following characteristics or some combination thereof:

  • 75% of all light vehicles will have start / stop technology
  • 70% will have advanced direct injection gasoline engines
  • 68% will have a seven, eight or nine-speed (or greater) transmission
  • 65% of engines will be turbo-charged
  • Average curb weight will decline by 10-12% to approximately 3,500 pounds (1,590kg)

Evaluating options

Engineering teams have a massive undertaking in evaluating options and determining the final route to production. Material substitution will play a critical role in decreasing vehicle weight, particularly advanced high strength steel (AHSS) and aluminium.

Fundamentally, OEMs will continue to address the following questions when selecting the best path forward to meet mandates:

  1. What will give me the biggest bang for my buck?
  2. What are the costs to implement the proposed changes?
  3. Does the supply base have the manpower and technical know-how required to serve multiple high volume applications?
  4. What are my competitors doing and is it working?
  5. How will these changes impact my customer?

OEMS will look to their engineering teams to provide insight and recommendations on how to best meet their design desires. Evaluation criteria that the engineering teams will assess during the design process as it relates to weight and material selection may include:

Cost for weight savings

  • The cost for saving weight is not limited to the material being substituted; overall costs need to be investigated, such as cost to convert production lines, training, joining etc.
  • Supply Chain / Logistics (global platforms)
  • As more OEMs turn to global platforms, the availability of advanced materials may be challenging, often requiring multiple variations to accommodate local availability of specific materials

After Sales – Service / Repair

  • An OEM’s burden doesn’t end at the point of sale; there needs to be a sound system in place to address sustainability in the event the vehicle needs service work or after collision repair; particularly as AHSS and aluminium penetration grows, so too is the challenge of repair facilities that have the know-how and equipment to adequately handle the repair work

Materials: A beneficial equation

OEMs tend to be more tolerant towards greater investments within the powertrain versus spending on other weight saving methods such as materials substitution. The image below depicts qualitatively an OEM’s propensity to spend more on powertrain improvements vs. all other means to save weight.

However, Ducker Worldwide has tracked light vehicle material content for nearly 20 years; recent studies indicate that OEMs in North America are increasingly turning to the use of AHSS and aluminium to meet their weight savings goals.

AHSS utilisation levels are on track to surpass 480 pounds per vehicle by 2025. Aluminium growth is tremendous in its own rights; by 2025, aluminium in all forms (rolled, extruded, cast, forged) will be over 500 pounds per vehicle. Rolled aluminium content within light vehicles is expected to reach 150 pounds per vehicle by 2025, up from less than 15 pounds per vehicle in 2012.

Steel and iron in its various forms together account for over 50% of curb weight today, while all light vehicle aluminium forms total ~10%. Steel will continue to account for the largest share of material content in light vehicles for the foreseeable future, while aluminium’s rapid growth rate is primarily due to aluminium sheet for closure applications.

Material utilisation trends

The level of research and innovation that the materials industry has witnessed over the last 24-36 months is nothing short of astounding. Both the steel and aluminium industries are hard at work developing innovative ways to save weight and cost, benefiting both the OEMs and the consumer. The table below highlights examples of products from both the steel and aluminium industries where the right material was designed and selected for the specific application and specific engineering challenge. Steel continues to excel in applications that require high strength, while aluminium is preferred for applications that are stiffness governed.

Material and body engineers have been working with steel and aluminium for over a century. However, the increased utilisation of AHSS and aluminium in light vehicles produces a new set of downstream challenges that will need to be addressed. Repairing, repainting and replacing various parts will be necessary, including the tools used and the training of employees. In spite of challenges, both aluminium and steel are the preferred forerunners to many of the other light weight alternatives for high volume use in light vehicles.

The right materials for the right applications

Moving forward

The steel and aluminium industries have transformed themselves from basic raw material suppliers to being viewed as integral partners. They are working to anticipate OEM pain-points and becoming solutions providers. For instance, raw material suppliers are pro-actively approaching OEM customers with light weight design alternatives during industry technology show case events and design challenge events.

Both the aluminium and steel industries are hard at work developing their ‘next generation’ of products that are stronger, lighter and even more cost effective. Anticipated changes to look out for within the coming years from the steel industry are the roll out of press hardened steels that offer increased tensile strengths with lower elongations as well as “generation three” steels. Generation three steels are expected to offer even greater strengths than most of the current ultra-high strength steels. The drop in price is associated with its ability to be cold formed. The aluminium industry is also developing more formable heat treated alloys such as 6451, and scrap friendly alloys for easier closed loop recycling, and new coatings to improve adhesive bonding and paint adherences.

AHSS and aluminium utilisation is forecasted to reach unprecedented penetration levels, and both are likely to be essential pieces of the puzzle to meet mandates in the years to come. OEMs will continue to exercise their options to achieving mandates by essentially balancing powertrain efficiencies, aerodynamics and light weighting. Whichever way you cut it, Steel + Aluminium = Weight Savings.

Abey Abraham

This article appeared in the Q4 2014 issue of Automotive Megatrends Magazine. Follow this link to download the full issue.