Magnesium Alloys: The Future for Automotive Lightweighting?

Experts gathered at the University of Waterloo discussed the challenges and opportunities ultralightweight alloys pose

MMLV Lightweight Concept car. Image courtesy of Tim Skszek, Magna Intl.

MMLV Lightweight Concept car. Image courtesy of Tim Skszek, Magna Intl.

In January the University of Waterloo Centre for Advanced Materials Joining (CAMJ) hosted Auto21: Innovation Through Research Excellence, a workshop on automotive welding. The daylong event focused on the challenges industry is facing on the road to lightweighting vehicles through the use of a variety of dissimilar materials.

The potential shining star in the metals world for lightweighting is magnesium alloys.

“The weight reduction we experience using aluminum in place of steel is 40 per cent,” said Adrian Gerlich, associate professor in the Department of Mechanical and Mechatronics Engineering at Waterloo. “Using magnesium alloys in place of aluminum sees a further comparative weight reduction of between 30 and 40 per cent.”

Gerlich, who organized and hosted the workshop, noted that there are challenges with magnesium alloys, however.

“While it has huge potential, it is less stiff than aluminum, so it requires the addition of stringers and stiffeners,” he explained. “It also has to be formed at a higher temperature if it is to be used for stamped parts.

“Corrosion is also an issue. The oxide of magnesium isn’t inherently protective; it continues to corrode, so careful protection of the material is required.”

The biggest issue as Gerlich sees it is welding the alloys.

“There is a high potential for porosity in these alloys, along with a tendency for distortion and cracking.”

All these negatives make it sound like a daunting task to make magnesium alloys even close to viable. But a number of Canadian researchers in both the public and private sector are exploring each issue in turn to see how best to manage the incorporation of magnesium alloys in the cars of the future.

Prototype Vision

Industry was well-represented at the workshop by Tim Skszek, senior manager, government partnerships at Magna. Skszek led a team at Magna that was given the task (by the U.S. Department of Energy and in partnership with Ford Motor Co.) of developing two multimaterial lightweight vehicle (MMLV) concepts.

Using a 2013 Fusion as the base model from which to start, the first vehicle design was based on an aluminum-intensive multimaterial architecture vehicle.

“We were able to produce a complete vehicle that was 23 per cent lighter than the 2013 model year production vehicle,” said Skszek. “We fabricated and tested seven complete prototypes of this aluminum-intensive model.”

The goal for the first model vehicle (or Mach I, as they termed it) was a 25 per cent mass reduction. This Mach I aluminum-intensive vehicle achieved a 364-kg mass reduction, which resulted in a 962-gallon fuel savings over a 250,000-km lifetime.

The goal for the Mach II was a 50 per cent mass reduction.

“That mass reduction is not an affordable alternative if we maintain the footprint, performance, and functionality of the baseline vehicle,” Skszek said. “What we found out is that unless you eliminate the heater, radio, power seats, etc., it just is not possible. Realistically, it is not possible to lightweight many of the vehicle systems such as glass, seating, and interior trim by 50 per cent. The MMLV project helped adjust the government’s vision to a realistic goal of 30 to 35 per cent reduction.”

No prototypes of the Mach II have been built, but it really captures the desire of the industry to develop next-generation materials and next-generation manufacturing for the vehicles of the future. As Skszek explained, it also helps identify the gaps that need to be filled if we’re really serious about lightweighting.

The Mach II design is a magnesium- and carbon-fiber intensive one, and as conceived it would be 51 per cent lighter than the 2013 Fusion (after having eliminated many of the features mentioned previously). The concept achieved a 797-kg mass reduction relative to the 2013 production vehicle. The baseline production Fusion uses 2.3 kg of magnesium, the Mach I design included 16 kg of magnesium. The Mach II ups that amount to 75 kg, including stamped outer and inner panels and a cast magnesium chassis and powertrain components.

“Essentially the exterior Class A painted surfaces, which include the doors, fenders, roof, and deck lid are magnesium,” said Skszek. “It breaks down to being 51 per cent magnesium sheet for body and closures,” he said. Overall, magnesium ends up accounting for 21.4 per cent of the vehicle weight, compared to just 0.2 per cent of the Mach 1.

As a result of the significant mass reduction associated with the Mach II vehicle, it makes it possible to downsize the engine, while maintaining the performance associated with the baseline vehicle. This would result in a total life cycle mass-induced fuel savings equal to 7,984 liters, or 2,109 gallons.

Current Viability Challenges

While the numbers for magnesium are awe-inspiring, Skszek is realistic about its viability. Right now it just isn’t for a number of reasons.

Galvanic corrosion is one issue mentioned before, as is general corrosion. However, as Dr. Joey Kish explained, a new coating that Henkel has developed is effectively addressing that issue. Kish is associate professor, in the Department of Materials Science and Engineering at McMaster University, and he also presented results demonstrating the effectiveness of this coating on both cast and sheet magnesium alloys.

Formability at room temperature is a challenge – the material currently has to be stamped at temperatures as high as 240 degrees Celsius, adding to the manufacturing cost.

The issue of welding magnesium is another concern, one that Jessica Hiscocks, a PhD candidate at Queen’s University, is exploring under the supervision of Professor Brad Diak. She discussed strain localization and failure in similar and dissimilar magnesium friction stir welds during the workshop. Much research still needs to be done in this area.

So movement is being made on a number of fronts to find the answers. Skszek believes adapting a vehicle like the Fusion is still unlikely to happen anytime soon, partly just because of the extent of the investment required. “The Fusion is produced in seven different locations around the world,” said Skszek. Basically, to realign the facilities to manufacture a magnesium and carbon-fiber-intensive design would require a significant investment. He believes it’s much more likely that production use of magnesium sheet will occur in boutique applications and “bolt-on components” such as doors, hoods and deck lids in the luxury vehicle market segment. For instance, magnesium sheet is already used for the roof of the Porsche GT3R5 in production, manufactured by Magna International, incorporating a MgC coating developed by Henkel. “However, the panel requires hand finishing to achieve Class A surface requirements, significantly adding to the cost, and that high cost won’t work for high production,” Skszek pointed out.

The supply chain for magnesium also needs to catch up to the enthusiasm. Right now it costs about $15/pound, “but the energy cost involved in producing it is similar to aluminum, so once there are enough suppliers, the price should be manageable,” said Skszek. He sees the possibility of that price being lowered to $2/pound.

The challenge is the lack of a global supply chain for cast or sheet magnesium. Currently the main sources for magnesium sheet is from Korea and magnesium castings from Canada, although that may change soon with certain developments in Quebec.

Lastly, the surface of the alloy often requires hand finishing to be suitable for Class A vehicles, so this needs to be addressed.

While all of these challenges make the effective use of magnesium sound distant, government, universities, and industry are all working toward solutions, with the support of Automotive Partnership Canada and the Initiative for Automotive Manufacturing Innovation.

Right now the government is encouraging companies to apply for the new Automotive Supplier Innovation Program (ASIP) – the next step in the journey for innovation in automotive research. This program, aimed at small and medium-sized businesses, is meant to encourage the development of innovative products to meet new fuel efficiency, emission, and safety standards.

As Skszek noted during his presentation, it’s a Canada/U.S. community effort that is pushing these innovations forward.

Robert Colman can be reached at rcolman@canadianfabweld.com.

About the Author
Canadian Fabricating & Welding

Rob Colman

Editor

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Robert Colman has worked as a writer and editor for more than 25 years, covering the needs of a variety of trades. He has been dedicated to the metalworking industry for the past 13 years, serving as editor for Metalworking Production & Purchasing (MP&P) and, since January 2016, the editor of Canadian Fabricating & Welding. He graduated with a B.A. degree from McGill University and a Master’s degree from UBC.