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Modelling technological properties of commercial wrought aluminium alloys
KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.ORCID iD: 0000-0003-4986-6123
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.ORCID iD: 0000-0002-8494-3983
2009 (English)In: Materials & design, ISSN 0264-1275, Vol. 30, no 9, 3752-3759 p.Article in journal (Refereed) Published
Abstract [en]

The purpose of this paper is to model three important technological properties for aluminium alloys, based on their performance indices. The models are based on the chemical compositions and microstructure characteristics which are calculated using thermodynamical calculations. The properties that were modelled are the general corrosion, the weldability (MIG and TIC) and the machinability. The results from these models are to be used in materials selection and optimisation. The models clearly show that the general corrosion resistance is reduced for all alloy additions, except for small amounts of titanium. The largest influence on the corrosion is from copper and zinc. The weldability is negatively influenced by the copper and zinc-content, and for small additions of zirconium and titanium it is increased. The machinability is positively influenced by the hardness of the alloy or by adding lead or bismuth. For the non-heat-treatable alloys there was no influence from the composition to the corrosion resistance or the weldability. Copper and zinc which are added to increase the strength to the alloy strongly reduce both the weldability and the corrosion resistance but due to the increase in hardness increase the workability.

Place, publisher, year, edition, pages
2009. Vol. 30, no 9, 3752-3759 p.
Keyword [en]
Wrought aluminium alloys, Technological properties, Performance indices, corrosion behavior, machinability
URN: urn:nbn:se:kth:diva-18595DOI: 10.1016/j.matdes.2009.02.004ISI: 000267892200053ScopusID: 2-s2.0-67349212163OAI: diva2:336642
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2011-08-17Bibliographically approved
In thesis
1. Development of tools for integrated optimisation and use of aluminium alloys
Open this publication in new window or tab >>Development of tools for integrated optimisation and use of aluminium alloys
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Commercial alloys are continuously developed to improve their performance. Therefore it is useful to establish new optimisation software, which could be used in development of new materials or in materials selection. In the first part of the thesis, mechanical and technological properties, which are of importance in materials selection in mechanical design, are investigated. Two types of materials are analysed for the mechanical properties, aluminium alloys and stainless steels but only aluminium alloys for the technological properties.

Thermodynamic analysis has been used to evaluate the effect of the microstructure. Solid solution hardening has been successfully modelled for both aluminium alloys and stainless steels following the theories by Labusch and Nabarro. The precipitation hardening is most dominant for the hardenable aluminium alloys, but the non-hardenable alloys also increase their strength from precipitation hardening. The non-hardenable alloys are divided into different tempers, which differ in the amount of strain hardening. This has also been modelled successfully.

Combining these fundamental results with multiple regressions, models for mechanical and technological properties have been created. Separate models are developed for wrought aluminium alloys and stainless steels. For the aluminium alloys these include the solid solution hardening and the precipitation hardening. For the stainless steels, the thickness, nitrogen content and ferrite content are included together with the solid solution hardening.

The second part of the thesis concerns materials selection and materials optimisation. Traditionally materials optimisation includes a preliminary sifting due to the vast number of engineering materials. Then there is a discriminating search followed by an optimisation. In the optimisation part the concept merit indices could be used to rank the materials. A merit index only includes material properties, as for example the characteristic strength, the density or the Young’s modulus. A concept related to the merit indices are the merit exponents, which can be used when no explicit functions for the merit indices are available. The merit exponents can also be used when creating a control area diagram (CAD). These diagrams are used as a design tool, where both the geometry and materials are taken into account. For a situation with several geometrical variables the merit exponents can give information of how much the target function will be influenced by a given property change. This technique can be used for a variety of situations, when there is more than one property limiting the final sizes of a component. Principles for setting up a CAD are given together with how the merit indices and exponents relate to the final CAD.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. vii, 9-61 p.
Aluminium alloys, Modelling, Materials optimisation, Mechanical properties
National Category
Materials Engineering
urn:nbn:se:kth:diva-37609 (URN)978-91-7501-068-7 (ISBN)
Public defence
2011-09-09, F3, Lindstedtsvägen 26, Stockholm, 13:00 (English)
QC 20110817Available from: 2011-08-17 Created: 2011-08-15 Last updated: 2011-08-17Bibliographically approved

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