At WCX18: SAE World Congress Experience earlier this month, ArcelorMittal and Honda unveiled the world’s first outer and inner door ring system to better balance strength and performance while removing additional weight from the vehicle. The partners co-engineered the system for the 2019 Acura RDX.

The inner door ring comprises five different gauges of ArcelorMittal’s patented press hardenable steel (PHS) Usibor 1500, while the outer door ring comprises 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—laser ablation—takes place.

Usibor is a coated steel; laser ablation (using a laser to remove material from a solid surface), prepares the edges by removing the coating to enable a safe, strong weld while also preserving corrosion resistance around the welded area.

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.

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. 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. This vehicle also features a panoramic sunroof, and with two door rings, it really performs well.

—,Joe Riggsby, Acura RDX body development leader, Honda R&D Americas

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%, 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. 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.

—Todd Baker, president, ArcelorMittal Tailored Blanks Americas (AMTB)

The partnership between ArcelorMittal and Honda goes back nearly a decade, Baker noted. 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 replaced conventional multi-piece, spot-weld designs. The technology was implemented in additional Honda vehicles including the Pilot and Odyssey.