A continuing concern for the auto industry is how to make vehicles lighter to improve fuel efficiency.
Automakers have addressed lightweighting for years -- both for traditional internal combustion engine vehicles as well as electric vehicles.
The steel industry faces competition to maintain its position among automotive materials. Aluminum and composites have been used to take weight out of vehicles.
John Catterall is vice president, automotive program, for the American Iron and Steel Institute (AISI). He assumed the post on March 1. He is responsible for leadership of the Automotive Applications Council, a group of member steel producers, in automotive research, education and technology transfer activities.
Catterall also coordinates the steel member company collaborations with the Auto/Steel Partnership a partnership between AISI members, automaker representatives from FCA US LLC, Ford Motor Co. and General Motors Co. and other steel-related consortia.
SME Media interviewed Catterall by email about the current state of vehicle lightweighting.
QUESTION: What’s your assessment of where the auto industry stands concerning lightweighting?
CATTERALL: The need for lightweighting in the automotive industry has led to historic innovations in advanced high-strength and ultra-high-strength automotive steels (AHSS and UHSS), including ongoing development and commercialization of stronger and more formable third-generation advanced high-strength steels (3rd Gen AHSS).
This has largely been driven by the current automotive product mix, which favors full-size pickup trucks, SUVs and crossovers over passenger vehicles, as well as, low oil prices.
With more than 200 grades of innovative sheet steels available to automakers today, and more in development, applying the right grade for the right application allows for exceptional occupant protection, durability and crash energy management. New lightweight high-strength steel makes applications 25 percent lighter and ultimately stronger. AHSS reduces vehicle weight to achieve better fuel economy.
The steel industry has collaborated closely with the automotive industry, working to develop new grades of steel that meet the needs of the automotive industry and the latest vehicles on the market. Introduced in 2018, the development of 3rd Gen AHSS is an ideal example of this and has gradually made its way into production-vehicles.
QUESTION: What have been the main lightweighting advancements for steel during the past three to five years?
CATTERALL: New 3rd Gen AHSS have been developed to meet key requirements for lightweighting automobiles that also provide higher strength where it is required and higher formability where it is needed. Automakers can combine the potential mass reduction enabled by AHSS with appropriate engine technologies to achieve their desired fuel-economy goals.
QUESTION: Where does the competition between steel and aluminum stand for lightweighting vehicles?
CATTERALL: With the many grades of steel available to automotive engineers and designers, we have seen a significant increase in the use of AHSS. The other trend we’re seeing is that advanced grades of steel are replacing milder grades and the newer grades require less material for the same application due to thickness reduction.
Since 2010, there’s been an increase in AHSS use to about 440 pounds per vehicle, up from 225. Steel is estimated to account for 53 percent of average light vehicle weight in 2020, down slightly from 54 percent in 2018 and from 55percent in 2013. A slight downward trend but steel is lightweighting itself to the benefit of the vehicle.
Aluminum is growing in closure panels, a key area where OEMs are trying to shed weight. There are however increasing government and safety regulations on the horizon that will require the use of stronger materials, like steel even in closure panels.
When looking at data for sheet material usage, the forecast for aluminum is essentially flat over the next few years, especially considering the trend toward larger vehicles in the North American market in recent years.
QUESTION: As the industry shifts toward more electric vehicles, how important will lightweighting be?
CATTERALL: As battery efficiencies increase and their costs drop, the premium an automaker will pay for mass reduction also decreases. AHSS-intensive vehicles can enable improved fuel economy and battery range through lightweighting at a lower cost than alternative materials.
Thinner and advanced grades of steel also enable optimization of space allowing for packaging of more batteries, which means traveling further on a charge. Since batteries are a big investment and a critical part of the powertrain of future vehicles, protecting them in a collision helps improve safety (or protection) of the battery, reduce repair costs and makes it less likely passengers will be stranded because of damaged equipment.
QUESTION: From the steel industry’s standpoint, what can we expect on the lightweighting front over the next three to five years?
The steel industry is committed to continuous collaboration with our automotive customers to meet their lightweighting needs through ongoing development of innovative grades and advanced manufacturing and design solutions.
Automakers have yet to recover financially from the effect of the COVID-19 shutdowns, and cost will become even more important in the next few years. OEMs can design and manufacture new vehicles more cost-effectively using steel over alternative materials because they can maintain their existing manufacturing infrastructure, better enabling automakers to keep vehicle prices down. These savings are further transferred through a lower cost of ownership, purchase price, insurance, and repair to consumers.