InCar plus is the most extensive internal R&D project that ThyssenKrupp has ever undertaken. It encompasses the group’s interdisciplinary expertise to generate more than 40 individual solutions for cost-effective vehicle weight reduction without sacrificing performance, as well as the use of advanced manufacturing technologies that are validated and can be implemented with current processes. Another component is scalability, with modular lightweight design concepts that can be utilized across multiple platforms and vehicle programs. The project was initiated by developing an independent body-in-white structure to serve as a reference benchmark for the various body solutions. The reference structure is a representative upper midsize class vehicle that was derived through extensive comparative studies of bodies manufactured by various OEMs. With a lightweight index of 2.7, it surpassed its previous InCar reference structure that was developed in 2009, due to improved design and advanced material utilization. Timo Faath, General Manager Technology, ThyssenKrupp Steel North America, Inc., spoke with Automotive Engineering about the InCar plus project and some of its promising technologies. Faath is responsible for the areas vehicle technology, customer project engineering, product strategy, and quality.
One of the project’s innovations is a B-pillar featuring a new TriBond material. Can you talk about this development?
We have several different solutions for the B-pillar. Our reference structure is already a MBW 1500 tailored tempered (tt) solution. We’ve developed some hot-stamped solutions—one is MBW 1900 tt and the other is TriBond 1400, a pretty interesting new material development. And we also have some cold-stamped solutions—DP-K 700Y980T and DP-K 780Y1180. TriBond is a material development; we don’t have it in serial production yet. It’s like a sandwich material. We take three slabs, to simplify it, stacked on top of each other and run them through the hot rolling mill, the cold rolling mill, annealing, and offer it as aluminized-coated. The only process that is added is that stacking up of the slabs. The slab in the middle is a conventional MBW 1500; the thin outer slabs are lower strength. What that does for us is…no cracks [in drop tower and 3-point bending tests], higher ductility with almost the same strength level. When you look at the plain mechanical properties, the elongation is still defined by the core slab—it’s still 4.5-5% elongation. What’s really better for that material is the bending angle—for a conventional 1500 it’s about 65°, with the TriBond 1400 it goes up to 85°, and the TriBond 1200 it’s actually where the test ends at 135° bending angle. So this is the real highlight of that material…It is a monolithic material that can be stamped in a conventional hot stamping process—no process modifications necessary. So this is pretty exciting for us.
How does the new material compare cost-wise?
For a cost and weight comparison, our reference structure—the MBW 1500 tt B-pillar—weighs about 15.4 kg, and with our TriBond 1400 solution we were able to get the weight down to 14.1 kg. To be honest with you, it’s kind of difficult for us to do cost calculations on the material because it is not [in production yet]. We do see an increase compared to the conventional material [€38.80] just because we have an additional process step, but this may well go down a little [currently stated as €40.60]. So very attractive weight and slightly higher cost make the solution very attractive. We have a couple solutions [in InCar plus] where the weight reduction comes with reduced cost, just because you save material and material cost is the biggest portion of your part cost; that sometimes works in our favor. But it’s still attractive.
Any other possible applications for the material?
It doesn’t have to be a B-pillar. So we have a couple of different applications for that material. It will work for front rails as well…I showed a drop tower test of a front rail that looked very good. In today’s vehicles, you don’t use hot stamping for front rails because it’s not enough elongation in the part. But with TriBond we would actually have that option to use it in front and rear rails where deformation is required. That might actually be a better application than the B-pillars. But in B-pillars there’s a lot of expensive solutions out there—tailored tempering, tailor welded blanks, tailor rolled blanks—that are very complicated to control from a hot-stamping-process perspective. With the TriBond, you just throw it in your hot stamping press and you’ve got a ductile part.
You have also presented A-pillar and bumper concepts as part of InCar plus. Which of these technologies is closest to serial production?
That’s a tough one. Throughout the InCar project we tried to offer different serial production levels. Some of the solutions our customers can buy today. Some solutions are still under development. The reason why we do it like that is our customers—some of them work on next-generation vehicles, and some of them have a problem today with their serial production vehicle where they need a solution. So we’re trying to reach as many customers as possible. Generally speaking, hot stamping is a big topic for everybody, and we know there’s some OEMs trying to do it themselves [particularly] in Europe. Whenever OEMs invest in hot stamping, I don’t think they want to do it the conventional way—or follow what their suppliers already do for them—they want to come up with more sophisticated solutions. Some of the stuff [in InCar], tailored tempering being one of them, is very promising and I think we’ll see a lot more of that in the future in NAFTA; it’s already out there in Europe. Pretty much everything that we show [related] to hot stamping is very promising.
Is InCar plus still ongoing? Or are the individual solutions taking different development paths now?
We keep pointing out that 40 solutions were developed; actually if you look into the process, we’ve developed much more than that. But not every solution turned out to be feasible or show the performance that we needed. The 40 we selected are really good and show a lot of benefit. We do road shows—we go from OEM to OEM and present the results—we get engaged in engineering projects where we try to adopt our ideas, our products into their vehicles, into their package situation. And then typically the technologies evolve. We’re not usually seeing the exact same part as we had it in InCar in a serial production vehicle, but that’s why we do it. We want to get in conversations with our customers.