In contrast, the authors say, the world’s leading steel mills are “apprehensive and mystified.” While they are developing ever-stronger and more formable automotive sheet products, their story is not resonating with the automotive vehicle designers as strongly as they wish.

Each week, it seems, there’s another press release about another automotive company planning to use more aluminum sheet, especially for closures (hang-on parts); and, this is happening even though stamped aluminum sheet costs at about three times stamped steel sheet. Nevertheless, the steel companies are plowing ahead with their exciting new automotive sheet products.

—“AutoBody Warfare”

Aluminum automotive sheet deliveries will show spectacular gains through 2018, the WSD report says. Reasons include surging deliveries for the Ford F-150 light truck and significant growth in aluminum closures (hang-on-parts such as hoods, doors, trunk lids and tailgates). WSD forecasts that aluminum sheet deliveries to automakers, before yield losses that result when the products are blanked, stamped and otherwise fabricated, may rise to 2.68 billion pounds in 2018 from 504 million pounds in 2014—for a growth rate of 51% per year compounded.

However, although the the CAFE standard becomes even more rigorous from 2021 to 2025, a wider array of advanced high-strength steels will be ready for use by automotive design engineers. There is more potential for weight cuts in the body-in-white—the frame of the automobile excluding closures—because for most vehicles, the BIW weighs about 3.5 times the weight of the closures that include the doors, hood, trunk and/or the tailgate.

Based on the expectation of large improvements in engine performance, weight savings requirements looking ahead to 2018 and 2021 are not particularly severe, WSD suggests. Automotive designers using steel may well exceed in the body-in-white the weight savings needed to achieve the MPG targets. A Ricardo Strategic Consulting study, contracted for by WSD, indicates that, for a steel- intensive, non-aluminum-bodied light truck, the reduction in the weight of the body-in-white and the closures, is:

• From 2014 to 2018: 1.7%, or 25 pounds.

• From 2018 to 2021: 11.4%, or 166 pounds.

• From 2021 to 2025: 13.5% or 188 pounds.

WSD also modeled four other vehicles of different sizes with roughy similar results.

Other key findings of the WSD study include:

• Once engineers decide to redesign steel-intensive vehicles from the ground up, they will implement sizable and relatively low-cost weight savings with advanced high-strength steels, enabling continued supply of steel closures;

• Advanced high-strength steels, even if priced substantially higher than other auto sheet are quite attractive given their weight savings relative to aluminum, and will rise to 23.7 million tonnes in 2025, a 330% gain displacing mild steel and alternative materials; and,

• Automakers will not widely adopt aluminum or other alternative materials during their next round of design, and the growth in aluminum sheet in cars, SUVs and light trucks will peak about 2018.

Aluminum growth may “hit the wall” for three reasons in WSD’s opinion:

• Very few, if any, new aluminum-bodied light trucks or high-production smaller vehicles will come on line in the future. These vehicles are higher cost to build.

• Few gains for aluminum for the inside portions of the vehicle’s body-in-white applications, where steel’s strengths seem to be unassailable.

• Once automotive design engineers decide to redesign steel-intensive vehicles from the ground up (as did Ford Motor with its aluminum-intensive F-150 light truck in 2009), they will implement sizable and relatively low cost weight savings with advanced high-strength steels (AHSS). The savings in the body-in-white may be sufficient for the design engineers to decide to utilize lower cost, although heavier, closures made from steel.