More than 1,300 leaders, engineers and designers came together at Great Designs in Steel on May 16 in Detroit. ArcelorMittal and other Steel Market Development Institute's (SMDI) automotive investing companies coordinated the premier forum focused on the latest trends and applications in automotive steel technologies. Celebrating 17 years, GDIS showcases the latest steel products and solutions used to design and build strong, affordable, fuel efficient and environmentally sustainable passenger cars, sport utility vehicles and light trucks.
GDIS is a multi-track program and featured 28 technical presentations on new steel technologies including AHSS, automotive safety and manufacturing technologies. This year's event featured one session by ArcelorMittal and two about ArcelorMittal co-engineering efforts found in two 2019 vehicles, the Ram 1500 truck and Honda’s Acura RDX.
CFRE in combination with ultra-light high strength steel
Sriram Sadagopan, group manager of applications technology at ArcelorMittal Global R&D Center, presented on how ArcelorMittal is lightweighting vehicle doors by using ultra thin advanced high-strength steels reinforced with low-density carbon fiber materials.
In the constant quest for making cars lighter to meet stricter fuel standards, ArcelorMittal Global R&D and Diversitak Inc. (a Detroit based automotive polymeric materials manufacturer/supplier) partnered in an independent study to learn whether they could reduce steel gauge and still meet automakers’ requirements by using a new technology: Carbon Fiber Reinforced Epoxy (CFRE) in combination with ultra-light high strength steel.
The team researched the use of Dual Phase DP490 on door skins going down in thickness all the way to 0.5 mm. Different strategies of CFRE application were trialed and evaluated for panel stiffness, oil canning and dent resistance. The results were excellent, with the combination of CFRE and high strength steel meeting the performance requirements for door skin panels.
The promising results caught the attention of LightMAT, or Lightweight Materials National Laboratory Consortium, a government entity dedicated to developing and testing lightweight materials for industry. A two-year, $300,000 grant was given to Oak Ridge National Laboratory and Idaho National Laboratory for optimization of the CFRE material to enable ready adoption of this technology in automotive assembly plants.
“This is a very exciting project for us. The combination of very thin high strength steel and CFRE for certain applications can result in significant weight savings in the automotive structure while maintaining steel as the material of choice. Government funding for this steel-based project underscores the importance and viability of advanced high strength steel as an automotive material,” said Sadagopan.
Ram 1500 and Acura RDX showcase the potential of lightweight and high-performance AHSS solutions
In back-to-back tracks, ArcelorMittal's co-engineering technologies were highlighted in two new vehicles – the 2019 Ram 1500 and Honda’s 2019 Acura RDX.
Dave Reed, FCA's engineering manager for advanced body design, discussed the one-piece outer door ring used in the all-new Ram. The door ring is comprised of six individual steels including four gauges of ArcelorMittal's patented Usibor® 1500. The various steels are blanked at a blanking company then shipped to ArcelorMittal Tailored Blanks Detroit where the enabling technology, called laser ablation, takes place. Once ablated, the steels are welded together, with multiple quality control processes being to ensure precision. The blanks are then sent to hot-stamper Gestamp to be stamped into the final part required by the automaker.
Reed focused on the steel-intensive and lightweight design of the truck. A 98% high strength steel frame and an increase of high strength steel in the cab and box from 12% to 54% contributed to a total weight savings of 225 lbs. over the previous model.
Honda's Joe Riggsby, Acura RDX body development leader of Honda R&D Americas, spoke in great detail about the world's first outer and inner door ring system found on the 2019 Acura RDX. This co-engineering solution was developed in partnership with ArcelorMittal and better balances strength and performance while removing additional weight from the vehicle.
“A vehicle’s front body structure – or the area surrounding the driver and passenger – consists of a ring that serves as a critical part of the safety cage. The outer ring is where the doors and styling components affix, while the inner ring is where the airbags and all interior features attach,” said Riggsby. “Together, they make a continuous structure that encompasses the front door opening and offers a solution that is very stiff.
“The outer and inner door ring system takes our safety protection to the next level. The solution manages loads coming from the front of the vehicle and translates them through to the back of the structure. It also balances side type of crash modes to prevent intrusion into the cabin and protect the occupants from all directions," said Riggsby. "This vehicle also features a panoramic sunroof, and with two door rings, it really performs well."
In addition to enhancing vehicle performance and safety, including supporting a five-star rating for the narrow offset crash test, the door ring solution also supported the automaker’s lightweighting goals. Honda increased its use of ultra high-strength steels in the RDX by more than 50 percent, contributing to weight reduction of 42 lbs. over the previous model.
GDIS 2018 presentations are all available here. Links to the three presentations highlighted in the article are below: