Since about 60 per cent of every vehicle is made of steel, automakers and steel producers across the world have been investing in research and development (R&D) and engineering studies to invent new and advanced steel products. Though carmakers have been using steel for many years, the major emphasis in the past couple of decades has been on improving its quality, strength, lightness and formability.
Something that has caught the fancy of automakers is Advanced High-Strength Steels (AHSS), an innovative lightweight, but high-strength steel material. Since AHSS are stronger than conventional steel, they help automakers meet safety, efficiency, emissions and formability requirements at a low cost.
Steel continues to reinvent itself into new, better, stronger, more formable materials. AHSS itself have gone through advancements ever since it was first developed in the mid-1990s.
WorldAutoSteel, the automotive group of the World Steel Association, has been conducting a number of researches in this field. In 2002, it launched the results of UltraLight Steel Auto Body-Advanced Vehicle Concepts (ULSAB-AVC) that featured 11 different grades of AHSS.
In its recent research programme, Future Steel Vehicle (FSV), the automotive group in 2013 announced 39 per cent mass savings over a conventional steel benchmark. Cees ten Broek, Director, WorldAutoSteel, which comprises 18 major global steel producers from around the world, says, “The FSV featured more than 20 different additional and revolutionary AHSS grades. These materials are expected to be commercially available in the 2015–20 technology horizon.”
AHSS are currently the fastest-growing materials in automotive applications. “The sector’s present focus on fuel efficiency, light structures and low material costs, however, requires the application of ultra-high-strength formable steel. To achieve the strength required, OEMs have relied on multiphase steel since the 1990s,” says Olli Hurskainen, Vice-President, Coated Products, Ruukki Metals.
Carmakers were quick to incorporate these latest steel products into their portfolio. Honda was one of the first companies that incorporated some of the highest grades of AHSS into body structures. BMW has also successfully integrated several steel grades for its various product ranges. General Motors has used a significant amount of AHSS for its Chevrolet Silverado truck. The 2013 Ford Escape has also made effective use of AHSS grades.
R&D and Innovation
With growing competition from other lightweight materials such as aluminium, carbon fibre and reinforced plastic, steel companies realise that they need to up the ante to remain competitive in the metal race. Major producers such as ArcelorMittal, Tata Steel and ThyssenKrupp are spending billions of dollars in R&D to come up with advanced types of high-quality steel for the automotive sector, which is the steel industry’s second-biggest customer, after construction, accounting for about 12 per cent of total production.
In 2012 alone, ArcelorMittal invested $285 million (around Dh1.04 billion) in R&D, 25 per cent of which was devoted to developing new products and solutions for the automotive sector. It also has an active R&D programme to develop the next generation of AHSS and hot stamping steel.
In the same year, ThyssenKrupp invested $823.5 million for increasing production of AHSS besides launching a dedicated R&D programme to cater to the sector.
With growing pressure to cut greenhouse gas emissions, new control standards are coming into play in the US, European Union, India and China between 2015 and 2017. This has necessitated automakers to develop vehicles that cut pollutants and offer better fuel mileage. Broek says, “We believe that automakers are going to be harder-pressed by the challenges of regulations and safety requirements, and they are going to continue to turn to steel as an affordable solution.”
ArcelorMittal is pushing forward with the development of high-strength steel for the automotive industry as it targets a full catalogue of products by 2017, ahead of the 2020 EU deadline for cutting average car carbon dioxide emissions to 95g/km.
Philippe Aubron, Chief Marketing Officer, Automotive Europe, ArcelorMittal, says, “Our S-in motion is a programme of 60-plus steel solutions designed to help car manufacturers reduce vehicle weight and fuel efficiency without compromising safety. It has the potential to save up to 73kg or 16 per cent of a typical C-segment vehicle’s Body-In-White (BIW) and chassis weight. The weight savings enabled by S-in motion also offer potential to deliver a 13.5 per cent reduction in carbon equivalent emissions during the total life cycle.”
Its other two products, Usibor 1500P and Ductibor 500P, also focus on weight reduction in cars. “For example, the weight of the optimised door ring was reduced to 12.7kg, a 19.8 per cent weight saving compared to a baseline C-segment vehicle by using these steels,” adds Aubron.
Finnish steelmaker Ruukki, one of the first suppliers to invest in multiphase steel production, has also developed products such as hot-dip galvanised Dual Phase and Complex Phase steels, marketed under the brand name Litec.
“Ruukki develops high-quality steel sheets and tubes that allow designers and engineers to create safety structures for cars in an affordable and sustainable way. We focus on ultra-high-strength materials,” says Hurskainen.
He says ultra-high-strength and rigidity are paramount for the steel cage that protects drivers and passengers. The industry is now, however, seeing an increasing shift towards the application of press-hardened Boron steels (PHS) over multiphase steels in the BIW.
“Implemented since early 2000, PHS has no spring-back effect after hardening, and it has higher yield strengths of about 1100 MPa or more and tensile strengths of currently popular 1500 MPa,” adds Hurskainen.
Aluminium, steel’s closest competitor in weight, has started to give steelmakers some trouble as the automotive industry is looking to explore other materials in order to reduce car weight. Ford’s latest F150 pickup with an aluminium body is one example. Other carmakers such as JLR, Audi and General Motors are also using more aluminium. Though automakers have always used aluminium, especially for engines, the usage of aluminium for other parts is slated to go up in coming years, say auto experts.
This latest trend poses a threat to the steel industry. However, steelmakers feel that aluminium will remain a much lower percentage of material in cars than steel. “The Ford150 has received a lot of media attention, but we continue to believe that steel is the best material for the auto sector. It has the strength, durability and capabilities to make strong and safe, but increasingly lighter car bodies. We are working very closely with our auto customers to ensure that we can partner with them to help them meet their emission and fuel efficiency targets,” says Aubron.
Hurskainen feels the rise of new materials such as aluminium and other light materials in the struggle to reduce weight has, however, caused a shift in focus for steel manufacturers catering to automotive OEMs.
Heavy metal will rule
“While the alternative materials offer great potential for weight reduction, their application in car parts that are crucial for the driver’s safety comes at high economic costs. Both the materials and the inherent manufacturing process require significant investments that are only feasible for cars in the executive and luxury segment,” Aubron says.
As developers try to invent advanced steel materials, the heavy metal will continue to dominate the auto industry. Iron and steel have historically made up 60 per cent of the weight of the average vehicle, and with the advances in high-strength steel that trend is expected to continue.
Broek says the changes in the steel industry are the same that have been happening since the automobile first rolled off the assembly line. Steel must continue to evolve with the ever-changing automobile.