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18 – 20 May 2021
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The battle of the battery housing: Steel versus aluminium

28 October 2020
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The increasing market share of electric vehicles generates growth for aluminium material, the favourite light and strong metal. An increasing material substitution in car manufacturing will further drive the demand for aluminium for electric vehicles. Both main types of electric cars, meaning the battery driven electric vehicles as well as the plug in hybrid vehicles, have a higher aluminium content due to their light weighting requirements. Nevertheless, the total aluminium utilisation in electric vehicles is expected to decrease marginally over the medium term, as more smaller, mass market vehicles will be produced.

Nowadays, all automobiles contain quite a lot of aluminium - on the average between 150 and 200 Kilograms. The lowest content is required for conventionally, gas or diesel engined cars, whereas battery electric vehicles as well as plug in hybrid vehicles need the maximum content of about 200 Kilograms per unit. Nevertheless, the types of aluminium used, differ rather strongly between the two basic types of electric vehicles. Regarding the plug in hybrids, the share of secondary castings ist more than 50 percent, whereas the battery electric car contains just about 25 per cent of secondary castings. These vehicles require the most rolled aluminium material - about a third of the total aluminium content. The share of extrusions, primary castings and secondary castings, is nearly equal in battery electric vehicles. As far as the plug in hybrids are concerned, the share of rolled aluminium is about 20 per cent, primary castings reach 25 per cent, whilst extrusions reach not much more than 10 per cent.

All this clearly shows that the aluminium industry will be affected quite differently by the market success of the various types of electric vehicles. The explanation of this phenomenon is rather simple: The switch to battery electric vehicles is removing big as well as relatively heavy components from the cars - like engine blocks and transmissions. The latter are being replaced by batteries and motors. But there are other major differences, too. Conventionally powered cars heavily utilise secondary foundry castings. However, electric vehicles will be much more reliant on primary castings. Just a few examples might illustrate the change of components and their weights: An engine cylinder block weighs about 18 to 20 Kilograms. A transmission housing in most conventional cars weighs between 20 and 22 Kilograms. Those are the parts which go out of car production. Incoming are battery housings of an average weight of 15 to 22 Kilograms and motor housings between 14 and 16 Kilograms.

Battle for the mass market

However, the battery housings do not have to be made from aluminium. Currently, these housings are seen as a key growth area for casters, who are competing vigorously for market share. There are two main metals for manufacturing battery housings, aluminum as well as high quality steel. The aluminium housings can be manufactured from rolled sheet metal als well as extruded. Currently, the mass market electrical vehicles mostly tend to be based on steel battery housings because steel is cheaper than aluminium. However, premium brand car manufacturers tend to continue to favour aluminium. It is interesting to see that Tesla has chosen steel battery housings for their basic model Tesla 3, whereas the other, more expensive models get aluminium battery housings.

In very broad terms, currently there are three tendencies visible regarding the use of aluminium in electric cars:

1.) Electric cars of any kind, battery electric vehicles or plug in hybrids, require more aluminium than conventionally powered vehicles.

2.) The switch to battery electric vehicles is favouring primary over secondary aluminium alloys.

3.) Currently the battery housing ist the key battle ground for aluminium producers as well as steel manufacturers.


CRU’s recent 25th World Aluminium conference in London showed, experts are currently expecting battery electric vehicles to achieve more than a quarter of total car sales in about five years and reach up to half of sales in about ten years. At least initially, the plug in hybrid cars will play an important role in the transition of car manufacturing towards electrification. Whereas many consumers are looking at electric vehicles favourably, experts seem to be sure that the first wave of main growth for electric vehicles will stem from the fleet business.

Regarding the major light vehicles production areas of the world, China seems to be the best country in overcoming the Covid-19 catastrophe. Chinese production fell about 5 per cent in 2020 and is expected to rise by about 11 per cent next year. Asia Pacific (without China) suffered from a fall of 22 per cent in 2020 but expects a production increase of 17 per cent next year. North America will have to accept a production decrease of about 23 per cent, if not more, in 2020. However, the coming year should bring an increase of about 16 per cent. Europe fared worst in 2020 with a decrease of around 25 per cent. Nevertheless, 2021 is expected to bring an increase of 28 per cent. Thus, Europe is forecasted to be able to over-compensate the losses of 2020 with higher sales - probably thanks to China..


Author: Katharina Otzen-Odrich   


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