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EDITORIAL – Automakers expected to increase use of high-strength steel to achieve lightweighting goals

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Advanced high-strength steel is driving innovation in the automotive industry and helping automakers reach their lightweighting target

‘Lightweighting’ is a buzzword in the automotive industry nowadays. Strict emission and fuel economy norms are pushing automakers to look for materials that will help them cut overall weight of the vehicle without compromising its safety and increasing manufacturing cost significantly. Automakers are now turning toward high-strength steel (HSS) to address the lightweighting issue.

At the 2018 North American International Auto Show (NAIAS) in Detroit (United States), Steel Market Development Institute (SMDI), a business unit of the American Iron and Steel Institute (AISI), in collaboration with Ram, showcased the all-new 2019 Ram 1500 with extensive use of HSS in the cab and frame. According to Fiat Chrysler Automobile (FCA), it achieved weight reduction of nearly 225 pounds in 2019 Ram 1500 using 98% HSS for the frame and 54% HSS in the core body structure. “The Ram is a great demonstration of how steel is driving automotive innovation with the truck’s capability, efficiency, durability and weight reduction,” Jody Hall, vice president of the automotive market for Steel Market Development Institute (SMDI), said in a press release earlier this month. 

HSS is lighter than conventional steel and engineered to meet challenges with regard to safety regulations, emissions reduction as well as robust performance, at affordable costs. HSS is available in different grades that help automakers meet various performance demands across different parts of the vehicle. The 2019 Ram 1500 displayed at NAIAS 2018 included four panels featuring conventional steel, HSS, AHSS and ultra-high-strength steel (UHSS). The panels were of different thickness and strength to show visitors how various grades of steel can be applied to different areas of a vehicle for lightweighting, strength and occupant protection.

Emerging steel grades have the potential to substitute aluminum parts, which are relatively more expensive to produce. According to the World Steel Association, a Belgium-based non-profit organization, new grades of AHSS enable OEMs to reduce vehicle weight by 25-39% over conventional steel. In a typical five-passenger car, the overall vehicle weight can be reduced by 170 to 270 kilograms (kg), which is equivalent to a lifetime saving of 3 to 4.5 tonne of greenhouse gases over the vehicle’s total life cycle.

Suppliers gearing up to meet demand

Most steel companies are investing heavily in AHSS. ArcelorMittal, one of the biggest producers of HSS in the world, believes that HSS will play a significant role in OEMs’ vehicle lightweighting efforts. In July 2017, the steelmaker announced plans to invest EUR67 million for construction of a new 600,000 tonne production line in Florange (France). The new line, which will be operational by mid-2019, will produce AHSS for the automotive industry. According to a report in World Steel Association’s website, ArcelorMittal is developing its new family of third generation advanced HSS, known as HF1050. The steelmaker had first introduced the third generation HSS in 2014. The company also offers “S-in motion” AHSS solutions. In September last year, the company developed “S-in motion” steel solutions for front seats to help automakers achieve significant weight reductions using AHSS. 

US-based NanoSteel is also developing AHSS to help automakers reduce vehicle weight. In February last year, the company announced the closing of a new round of equity investment led by GM Ventures. The financing also included automotive seating systems and electrical systems supplier Lear Corporation. At the time, NanoSteel said the proceeds from the investment round will be used for the commercialization of its AHSS for automotive lightweighting applications. NanoSteel’s AHSS features a unique combination of very high strength with the enhanced formability normally found only in low-strength mild steels. This blend of properties provides designers the ability to optimize part geometries resulting in thinner, lighter components, according to the company.  

South Korean steelmaker POSCO is also developing lightweight steel solutions for automotive application. In March 2017, the company announced development of ‘giga steel’, a high-tensile steel that is lighter but stronger than existing steel plates. 

Multi-material approach

Automakers are also employing a multi-material approach—with high steel content—to reduce vehicle weight. In the new Audi A8, the automaker has used four materials—aluminum, steel, magnesium and carbon fiber-reinforced polymer (CFRP)—in the weight-bearing body structure. The aluminum components make up 58% of the new Audi A8 body, followed by steel parts (40.5%). The 2017 Pacifica Hybrid has almost 72% of its body structure made from a variety of high strength steel. The model also features aluminum and magnesium. FCA said it achieved weight reduction of nearly 120 pounds from the 2019 Ram 1500’s chassis by using high-strength steels, composites and aluminum compared to the previous generation. The recently launched 2018 Ford F-150 also uses a combination of HSS and aluminum to achieve weight reduction.

Automakers are accelerating their efforts to find new materials. Earlier this month, Volkswagen Group of America joined the LIFT (Lightweight Innovations For Tomorrow) institute to advance its research into lightweight metals with an aim to reduce the weight of future vehicles. Earlier this month, French luxury automaker Bugatti developed a new titanium brake caliper using 3D printing technology. The new titanium caliper weighs 2.9 kilos, which is about 40% lighter than the aluminum component currently used, according to the automaker. However, use of this metal has been limited to racing cars and a few premium models because of its high cost. Edwin Pope, principal analyst, IHS Markit, said, “Titanium and 3D printing in automotive have been used for quite some time now, but for racing oriented cars in particular and not mass produced vehicles.” Pope does not foresee increasing use of titanium for mass vehicle production in near future. Pope believes automakers will continue a multi-material strategy to achieve lightweighting in vehicle production. The material mix strategy differs from one automaker to other as some prefer aluminum for body structures while others prefer high strength steel. In some cases, platforms which were previously fully aluminum now contain a sizable quantity of HSS—the new Audi is a case in point. 

With aluminium and carbon fiber still being costly alternatives, HSS is expected to gain more popularity in BIW applications. Hyundai-Kia, for instance, is increasingly adopting AHSS in their new vehicles. According to ArcelorMittal, four new models from the automakers feature high percentages of AHSS in the body-in-white (BIW); Hyundai i30 hatchback’s BIW features 53.5% AHSS, and Hyundai Kona and Kia Rio’s BIWs feature over 50% AHSS.

Analyst Details: Arti Anand