19 April 2018
ArcelorMittal has been working with automakers for years to co-engineer steel solutions that address safety, strength and fuel economy concerns in the most cost-effective way. ArcelorMittal offers an array of lightweight steel solutions and has seen tremendous growth and evolution of its door ring solution, co-engineered with Honda R&D Americas.
“The partnership between ArcelorMittal and Honda goes back nearly a decade. We’ve been fortunate to embed our engineers onsite at Honda and find ways to optimize steel blanks, identify effective applications of the material, and better understand what the customer is looking for,” said Todd Baker, president, ArcelorMittal Tailored Blanks Americas (AMTB).
As a result of collaboration, ArcelorMittal and Honda introduced the industry’s first hot-stamped, laser-welded outer door ring in the 2014 Acura MDX. The outer door ring – a key part of the body structure which gives the vehicle its strength and stiffness – replaced conventional multi-piece, spot-weld designs. The technology was implemented in additional Honda vehicles including the Pilot and Odyssey.
At WCX18: SAE World Congress Experience, held from 10-12 April 2018 in Detroit’s COBO Center, the partners unveiled the world’s first outer and inner door ring system to better balance 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 Joe Riggsby, Acura RDX body development leader, Honda R&D Americas. “Together, they make a continuous structure that encompasses the front door opening and offers a solution that is very stiff.”
The inner door ring is comprised of five different gauges of ArcelorMittal’s patented press hardenable steel, Usibor® 1500, while the outer door ring is comprised of four gauges of Usibor® 1500. The various Usibor® steels are blanked at a blanking company then shipped to the newly opened ArcelorMittal Tailored Blanks facility in 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 a hot-stamper to be stamped into the final part required by the automaker.
“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 19 kg/42 lbs. over the previous model.
“We see the door ring and our hot-stamped solutions continue to move through the industry,” said Todd Baker from ArcelorMittal's Tailored Blanks division. “We are working with more customers to implement them into more vehicles, and we see it taking place across vehicles lines. The application isn’t just limited to SUVs and minivans, we are seeing it in pick-up trucks and small cars. This validates our belief that the door ring and hot-stamped welded blanks offer a cost-effective way to make vehicles safer and lighter.”