Steel: Safety & Sourcing Small But Strong

According to Giancarlo Bertoldi, director for Body Engineering and Design at Fiat, “Improved safety is our principal driving force, although lower weight also plays a very important role.”

The Fiat Grande Punto is a small car. It is within the B-class category. It is 158.6 in. long, 66 in. wide, 58.6 in. tall, and has a wheel base of 98.8 in. Yet it has achieved a best-in-class, five-star occupant safety rating in the Euro NCAP testing. Part of this is said to be from the use of a door reinforcement bean made of an advanced cold-rolled high-strength steel that has a minimum strength of 1,000 N/mm2. This internal reinforcement is located in the front doors of the vehicles; the piece for the five-door model is made with 0.8-mm thick steel and the one for the three-door is 1.2-mm thick. According to Giancarlo Bertoldi, director for Body Engineering and Design at Fiat, “Improved safety is our principal driving force, although lower weight also plays a very important role.” Of the reinforcement, which provides high energy absorption for both frontal and side collisions, Bertoldi said, “We specified a very advanced geometry for the door internal waistline reinforcement mounted just below the front side window.” The component is produced by Wagon Automotive (www.wagonautomotive.com) in Italy through roll forming. According to the managing director of the firm in Italy, “This type of structural component is normally produced in two parts that are then welded together. But we have produced a closed profile with an asymmetric geometry, which is bent longitudinally in two planes.” Of roll forming steel, Bertoldi explained, “This process offers major benefits compared to pressing—higher quality and lower stresses in the material during forming. In my opinion, major carmakers such as Fiat will soon be replacing a large proportion of the traditional pressed parts with roll-formed components.” In addition to the five-stars, the component was also awarded the 2006 Swedish Steel Prize, sponsored by SSAB Tunnplåt AB (www.ssabtunnplat.com), a subsidiary of SSAB, a leading manufacturer of high tensile strength steel.

 

Steel Sources

Consider these numbers from the American Iron & Steel Institute (www.steel.org): 

Taiwan:
Malaysia:
China:
Russia:
Thailand:
Turkey:
India:
South Korea:
Japan:
Up 208%
Up 158%
Up 133%
Up 114%
Up 111%
Up 77%
Up 74%
Up 55%
Up 23%

 

Those percentages are the increases of imports of steel to the U.S. in 2006 versus 2005 quantities. Overall, there was a total of 45.3-million metric tons of steel imported, including 35.9-million tons of finished products. Meanwhile, the U.S. steel industry was operating at an average capacity utilization rate of just 75%. According to Ronald P. Krupitzer, vice president of Automotive Applications, AISI, while most OEMs and Tier One suppliers “buy the majority of their steel on contract from domestic mills,” hot- and cold-rolled sheet and galvanized hot-dip products, which are among the imported steel, are used by small parts manufacturers, as well as producers of service and aftermarket parts. What’s more, Krupitzer noted that while automotive OEMs may not directly source from foreign steel producers, the imports can have an overall downward effect on the pricing of domestically produced steel.—GSV

 

GM on Steel

According to Troy Clarke, president, GM North America, “Steel prices have gone up enough that we have to work to offset those costs. Precious metals prices have also risen, but lessening our use or our exposure to these higher prices is harder to accomplish with steel. Right now, we’re working on that problem from a sourcing standpoint because it is sometimes cheaper to buy the completed steel part than it is to make it, as long as it is being supplied from within the NAFTA footprint. Nevertheless, in the short run, we will have to absorb the rise in cost.”—CAS

 

“SMART” Steel

Mercedes says that the “tridion safety cell” protects occupants of the SMART fortwo occupants “like the hard shell around a nut.” And while some observers may see the occupants of the 106.1-in., sub-1,800-lb. city car that way, the safety cell is made of three layers of steel, of which approximately 50% is high-strength steel reinforcement. Additionally, both doors are reinforced with steel bars. In a head-on accident the side members support the front wheels which are designed to act as additional crumple zones. Since the SMART sits about 8-in. higher than a comparable small car, the occupants sit somewhat higher and—thanks to the relatively short 73.5-in. wheelbase—the opposing vehicle is almost guaranteed to hit an axle which absorbs some of the crash energy as it engages the rest of the vehicle’s structure.