Another step towards hitting the 2025 CAFE targets.
Colin Wright -
CleanMPG - Oct. 27, 2012
Will we see this used in the Cadillac ELR?
GM is testing an industry-first thermal-forming process and proprietary corrosion resistance treatment for lightweight magnesium sheet that will allow increased use of the high-strength and ultra lightweight alternative to steel and aluminum.
GM wants to expand its use of low-mass parts on vehicles around the world and will pursue licensing (read income
) opportunities related to this new technology. The goal is for suppliers to be able to use the process to provide significant amounts of magnesium sheet that will trim pounds from vehicle mass.
Magnesium weighs 33 percent less than aluminum, 60 percent less than titanium, and 75 percent less than steel. Together with more efficient engines and electric powertrains, increased use of magnesium in cars will help raise fuel economy. Is this a hint about the ELR?
Until now, automakers have struggled to make reliably strong magnesium sheet metal panels using traditional panel forming methods. GM’s patented process heats magnesium to 450 degrees Celsius (842 degrees Fahrenheit), allowing the material to be molded into precise, rigid shapes.
Using this process, GM developed a production-ready magnesium rear deck lid inner panel that withstood 77,000 robotic slams and 250-kilogram impact drops without any issues.
Die-cast magnesium is already in use in a variety of parts ranging from steering wheels to engine cradles, but GM is the first to use thermal-formed magnesium sheet metal in structural applications, and it expects magnesium sheet applications to grow with additional materials and process improvements targeted at reducing cost.
Simply put, high-strength lightweight materials is one of the most effective ways to improve fuel economy and performance.
GM R&D recently announced an industry-first welding technology for aluminum, which has already been used on the hood of the Cadillac CTS-V and liftgate of the hybrid Chevrolet Tahoe and GMC Yukon and will be used more extensively starting in 2013.
The US Automotive Materials Partnership estimates that by 2020, 350 pounds of magnesium will replace 500 pounds of steel and 130 pounds of aluminum per vehicle, given an overall weight reduction of 15 percent. This weight savings would lead to a fuel savings of between 9 and 12 percent.
Just on the now production-ready rear deck lid inner panel, GM can remove 2.2 pounds compared to one made from aluminum.
Automakers have struggled to make magnesium corrosion resistant while GM’s proprietary treatment for thermal-formed magnesium resisted 10 consecutive weeks of 24-hour environmental tests involving salt spray, 100 percent humidity and extreme temperatures.
Maybe one day GM's vehicles will become known for their
low weight... Today is not that day however.
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