New Non-Heat Treatable High-Pressure Die-Casting Alloys

Environmental and governmental pressures continue to push automakers worldwide to search for new areas of light weighting, and car structural components prove to be the new, fast-growing application for aluminium.

 As a result, adequate materials must be sourced, which can provide the high-performance requirements of the modern automotive industry, both for vehicles with conventional internal combustion engines and especially for new applications within electric vehicles (EVs). These materials must be lightweight, have good mechanical and thermal properties, must exhibit good crash performance and, importantly, must be cost-effective.

One material of choice amongst electric vehicle manufacturers, as well as for conventional automobiles, is cast aluminium. In particular, high-pressure die-cast (HPDC) aluminium alloy parts are increasingly used for car structural parts and are growing their share in battery housings in many current and upcoming EV models.

HPDC alloy parts, however, have some drawbacks. They cannot be used ‘as cast’, but rather require a lengthy heat treatment, which results in greater production costs. In addition, subsequent mechanical treatment is required to straighten the components into their original cast shapes.

The logical solution is to use alloys, which eliminate the process step and still yield sufficient mechanical properties – so-called Non-Heat Treatable alloys (NHT). Existing NHT alloys, however, are difficult to cast due to hot cracking tendencies.

To address this issue, Alcoa developed two new alloys with improved castability: EZCast-NHT™ A152 and A153.

The alloys are suited for complex thin-wall castings for car body structures for both electric vehicles and non-electric vehicles. There are expected to bring substantial benefits for HPDC foundries, OEMs, and multi-material vehicle integration teams.