Light weight Magnesium for automotive applications

Group members

1. Ganesh Mokate

2. Gaurav Mane

3. Rehan Sayyed

4. Kunal Mutha

5. Rohan Thorve 

Magnesium - introduction

Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray solid which bears a close physical resemblance to the other five elements in the second column (group 2, or alkaline earth metals) of the periodic table: all group 2 elements have the same electron configuration in the outer electron shell and a similar crystal structure.

Automotive Applications

Consumer’s preference for vehicle performance is increasing day by day. Fuel economy and air pollution are the deciding factors to select the vehicle. In the research aspects these are achieved by using alternate fuels, power train enhancements, aerodynamic modifications and weight reduction methodologies. Among these, weight reduction of a vehicle by alternate materials is the simplest and cost effective solution (Sameer, Suman 2014). Most of the castings in automotive industry are of steel/cast iron but when they look for alternate metals, Aluminum is considered the best option with good strength and cost when compared with magnesium and the usage of aluminum has grown more than 80% in the past 10 years. Most of aluminum and its alloys are used in car parts like cylinder heads, pistons, radiators, car’s body and wheel rims. It was been reported that one kilogram of aluminum has the capability to eliminate 20kg of CO2 emissions when replaced by a heavier metal, over the lifetime of the vehicle.  Magnesium is a powerful weight saving option its density is 36% to aluminum, 74% lighter than zinc and 79% lighter than steel (Aghion 2004). Based on the several studies the weight distribution in a vehicle is shown in Fig 9. The weight reduction using magnesium when compared with Al/Fe.

As can be seen from Fig 10, almost all areas of a vehicle replaced by Mg and its alloys contributed a weight reduction of 20-70%. Material alteration can be done in a vehicle in the three major areas like body, power train and chassis components. Body is the major contributor of total weight and also the first choice of structural material. There have been plenty of opportunities for researchers to use interior, exterior and seat frames made of Mg alloy materials. The power train is also another important element in a vehicle where the transmission and engine systems are linked to work together by various mechanical couplings. Creep resistant alloys like rare earth added Mg alloys have a good potential to work in this area. The chassis components are highly individual and show diverse characteristics. Wheels are the first replaced materials with Mg (Gaines et al. 1996). A variety of cast products are available to serve the purpose. The detailed areas of applications in motor components are given in Table 7

Magnesium was used in racing cars in the early 1920’s but Volkswagen Beetle used 20 Kg of magnesium in 1970. The usage of magnesium in automotive applications is expanding day by day as structural light weight material. Volkswagen group is leading the other companies like Mercedes Benz, BMW, Ford and Jaguar. Now around 14Kgs of Mg are using in Audi A4 & A6 models. AM50 & AM60 alloys are extensively used in interior parts of a car. General Motors (GM) used 26 kg of Mg alloy in savana & express vans

Automobile companies using Mg for various components

Fig 12

The same was also proved by MADM methods (Sameer , Suman, 2014). AM 50A & AM60B are more ductile and used in seats, wheels, instrument panels, cylinder head covers and so on. AS41 used in crank case and in transmission housings because of better fluidity (Siobhan 2012). ZE41 and AC63 is low pressure die casting alloys used in engine blocks. AZ31B by the extrusion process is widely used in the preparations of bumper support beams, valve covers, electric motor frames and oil pans (Mutua et al. 2011). Fig 12 shows different combinations of alloys with respect to properties that can be applied in the automotive area. The low creep properties, high corrosion and working at elevated temperature restricted more use of Mg in automotive applications. Creep phenomenon and the suitability of various Mg alloys is analyzed with respect to power train applications (Mihriban et al. 2012, Blawert, et al. 2004). Research is being carried out to increase the fatigue resistance of wheels and to improve the corrosion behavior of various Mg alloys. Teflon coatings are applied to improve the corrosion resistance (Mustafa 2008). Some work is being done to replace cast products with wrought Mg Products (Gaines et al. 1996). Steel panels are replaced by magnesium panels (Shin 2011). Kim et. al discussed recent developments in magnesium alloys, research activities their successful applications in Hyundai and Kia Motor Corporation(Jae and Han 2008). Research has been started in developing the magnesium alloys for high temperature applications (Tarek 2009, Luo 1994). The researcher’s contribution in the usage of Mg alloy products are significantly increasing with the well-known fact that lowering car weight by 100 kg makes it possible to save 0.5 liters of petrol per 100 km (Dobrzanski 2007,Andure 20112). In other words for every 10% of weight reduction, fuel economy increases by 6% for cars, and 8% for light trucks (Mutua et al. 2011). The automakers are thinking of using 40-100Kg of Mg alloys in a car and the amount of Mg alloys and its usage is going to increase by 300% in near future to accommodate the weight reduction and to save fuel (Mustafa

2008).

Conclusion

Magnesium alloys provides an opportunity to researchers to work in a broad area where there is a lot of scope to do. With the global awareness on environmental protection, Magnesium alloys usage in automotive industry has been considerably increased to reduce the CO2 emissions, and weight reduction of the vehicle thereby increasing the fuel economy. Weight reduction using magnesium in vehicles is interesting and proven with good results. However plenty of research is further needed to use cost effective methods on Mg processing, alloys development, improvement of mechanical and corrosion resistance properties to meet the future goals of reduction of mass and the amount of greenhouse gasses emitted.