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GM puts magnesium to the test

Keywords: Tags  General Motors, magnesium, thermal process, aluminum, steel, corrosion resistance, rear deck lid, lightweighting Greg Warden

CHICAGO — General Motors Co. is testing a thermal-forming process and proprietary corrosion-resistance treatment for magnesium sheet that would allow the automaker to increasingly use it as a substitute for steel and aluminum.

GM said that it wants to expand its use of low-mass parts on its vehicles and that it will pursue licensing opportunities related to this technology. The goal is for suppliers to use the process to produce a significant volume of magnesium parts in order to trim pounds from vehicle mass.

Magnesium weighs 33 percent less than aluminum, 60 percent less than titanium and 75 percent less than steel, according to GM.

Until now, carmakers have struggled to make reliably strong and non-corroding magnesium sheet panels. GM’s patented process heats magnesium to 842 degrees Fahrenheit, which allows the material to be molded into precise, rigid shapes.

The Detroit-based company has built 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 has historically been used in multiple critical parts, but GM claims that this is the first time thermal-formed magnesium sheet has been used in structural applications. The company expects magnesium sheet applications to grow with additional materials and process improvements.

On the production-ready rear deck lid inner panel, GM said that it can remove 2.2 pounds of weight compared with an aluminum deck lid inner panel.

"Every gram of weight reduction matters," Greg Warden, GM’s executive director for global vehicle body engineering, said in a statement. "Being able to replace heavier metals with one of the lightest will help us deliver better fuel economy while still providing the safety and durability (customers) expect."

Separately, the company’s research and development team recently developed a welding technology for aluminum which is expected to facilitate the use of that material in future vehicles.

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