Page 20 - MetalForming May 2012

This one ladle of steel being poured at a United States Steel ladle-metallurgy facility represents 200 tons of steel; a typical vehi- cle consumes one ton of steel.
Driving Toward the Next
Generationof Steelforthe Automotive Industry
While game-changing 980-MPa grades already are being deployed, 1180-MPa grades are under development and are targeted for 2014 production-vehicle platforms.
BY JODY SHAW
Avehicle’s body structure is its single largest component, representing 20 to 25 percent of its curb weight. The primary function of the body structure is to serve as a single bracket to which all other vehicle components are attached—in pre- cise alignment—to enable the vehicle to meet performance requirements under the complex loading of the driving environ- ment. Achieving this precision can prove challenging, considering the body struc- ture comprises an assembly of more than 100 individual stamped-steel parts. Dur- ing the past two decades, this challenge has increased as higher-strength steels have been employed in response to increasing crash-safety requirements, while simulta- neously enabling mass reduction to comply with fuel-economy regulations.
Strength Increases at a Quick Pace
The move to high-strength steels has been rapid. A body structure in the early 1980s comprised mainly mild steel with tensile strengths around 270 MPa. The next two decades saw a shift to high-strength low-alloy
Jody Shaw is director, technical marketing and product research, United States Steel Corporation, Troy, MI: 248/267-2608.
18 MetalForming/May 2012
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