Why composition limits of popular extrusion alloys form an increasing obstacle for aluminium recycling

Author: Bijlhouwer, F.

Source: Materials Technology: Advanced Performance Materials, Volume 24, Number 3, September 2009 , pp. 157-160(4)

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Abstract:

Recycling of aluminium reduces demand for energy intensive primary metal and will become increasingly important as more of the current structures, containing >600 Mt of aluminium alloys, come to the end of their service lives. In the specific instance of extruded sections, a conflict exists between the demand for 'primary quality' by extrusion companies to achieve the required extrudability and surface quality, and the widely promoted ability to recycle aluminium with no-loss-of-quality. Contamination, which can also arise during remelting and from the addition of master alloys and grain refiners, makes it very difficult to produce an alloy that falls within the composition limits, without blending with too much primary metal. The individual requirements of some extrusion companies mean that they can, in effect, be met only by using primary billet. It is argued that in many cases, these requirements, which deviate from AW6063 specifications, are excessively stringent and that acceptable result can be obtained from recycled material.

Keywords: EXTRUSION; COMPOSITION LIMITS; SPECIFICATIONS; ALUMINIUM; RECYCLING; SURFACE QUALITY

Document Type: Research Article

DOI: http://dx.doi.org/10.1179/106678509X12475883285384

Affiliations: Quality Consultants, Kooikershof 6, 5256 KD Heusden, The Netherlands

Publication date: 2009-09-01

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