Aluminium vs. Steel - (1) The changing tides in the automotive sector

To Steel or not to Steel… That is the question. To Aluminium… This might be the answer. The automobile industry is the one constantly shifting tides in technology and design to achieve perfection and quality. Everything is done with precision to maximise the output from the machines with as few resources as possible. After all, this is necessary as natural resources are limited and so are the resources which people can spare for an economical, ergonomic and environment-friendly vehicle of personal transportation. Moreover, safety is an important issue that the engineers keep at priority as people’s lives are at stake.

Aluminium body is the preferred material in sports cars

With car manufacturers around the world trying to pack in more punch with their offerings, the fight for better fuel efficiency and safety of the automobiles has intensified. With cutting edge designing and engineering capabilities, car manufacturers have carefully selected the materials and technology to complement each other when the car is firing on all cylinders, quite literally. Aluminium as a preferred choice of metal for building cars has rapidly gone up since Ford quite boldly manufactured the 2015 F-150, using as much as 97% of the entire body to be made from it. The weight of the model was 315 kg lesser than the preceding model, allowing it to brag about much better fuel efficiency (a 29% improvement) and drastically lower carbon emissions.

Pic courtesy: Ford

For substantial reduction in weight, the wary replacement of steel and iron usage in the cars have been thought over. It has everything to do with the improvement of fuel efficiency, increasing the manoeuvrability lessening of the harmful emissions and upping the safety standards of the consumer vehicle. Weight-wise, cast iron components are being replaced by the same volume of aluminium in half the initial weight. Stronger alloys having main components as aluminium are, therefore, the first and the key solution to weight reduction.

In Europe, more than 20% of the cars have an aluminium hoods. Numerous high-performance sports car bodies like Ferrari and Lotus are also produced in aluminium. In 2015, the average usage of aluminium in car manufacturing hovers around 9%. This figure is forecasted to become 15-16 % by 2025. In North America, this figure might go up to 19-20%, up from 10-11% in 2015. These trends can be attributed to pertinent factors such as high tensile strength, resistance to corrosion, light weight property and importantly, the recyclability of the material.

Very few materials like Advanced High Strength Steel (AHSS) have the competency to become an alternative to what aluminium can achieve. It has been calculated that the thickness ratio for aluminium is 1.5 times to that of steel in structural applications. In this case too, the weight reduction still stands at about 50% lesser than steel. The most frequently encountered ratio of thickness in structural applications is approx. 1.5 (Al vs. AHSS) which means, for instance, that a 0.8 mm steel component can be replaced by a 1.2 mm aluminium component. In this case, the weight reduction is still ~ 50%.

Aluminium alloy wheel

Aluminium is easily malleable as well as an excellent thermal and electrical conductor. This makes it suitable for manufacturing critical elements of a car like wheels, engine pistons, main body etc. Increasing the safety of the passenger can be made practicable with judicious use of specific aluminium alloys. It is, in fact, now possible to make the entire vehicle structure from aluminium today which will significantly improve the performance. An example of this is the Ford F150 truck that has changed the perception of aluminium’s practical employability. This has compelled Ford to take its innovation to newer heights with recent models like the latest Ford Edge Vignale.

So, what is so special about Aluminium? Why is steel losing out the edge to aluminium in the automotive industry in recent times? And what are the challenges that face the aluminium industry in doing so? Find out in our next post