Hoods Become a Materials BattlegroundHoods Become a Materials Battleground

Ford's top-selling F-150 pickup has sported an aluminum hood-the most popular automotive body panel application for the material-for ten years. Now, the steel industry wants to take it back. "With advances in medium- and high-strength steels, we can now offer at least the same level of hood performance and take customers closer to their ultimate mass-reduction goal for a significantly lower cost," says Ron Krupitzer, Senior Director of the American Iron and Steel Institute (AISI). "If you factor in manufacturing costs, an aluminum hood could easily cost three to five times as much as a steel hood." At the most basic level, the two primary functions of a hood are to keep the rain off the engine and look good, which has made this large body panel an easy target for automakers looking to get into a lower inertial weight class in order to meet overall Corporate Average Fuel Economy (CAFE) requirements. In fact, automakers frequently switch back and forth between aluminum and steel hoods, depending on whether the goal of the month is to reduce weight or cost. But the technical requirements for the hood are not zero, says Kruptizer, and in fact he says that hood performance is perceived now to be more critical as safety becomes an overpowering design requirement for automakers-something he says could tip the scales in favor of steel. He points to new pedestrian injury requirements being driven by the Europeans, as well as new crash rollover and side impact tests, which are impacting the whole architecture of the front of the car and likely to affect hood design. To help educate auto engineers on the benefits of medium- and high-strength steels in hood applications and to better understand the design criteria-with the ultimate goal presumably to achieve more design wins-the AISI commissioned a major benchmarking study comparing mass, structural performance, surface characteristics, and dent resistance capabilities, of aluminum and steel hood designs. The results of that study will be presented at the SAE World Congress in Detroit in March. The AISI also plans to release application guidelines for advanced high-strength steels to the auto industry in 2004.