The Effect of Mn and Homogenisation Procedure on Mechanical Properties and Grain Structure in Extruded AA6082

Abstract

Extruded profiles of AlMgSi-alloys are widely used in various industries such as the automotive industry, aerospace and in the oil and gas industry. To tailor the alloys for specific needs and applications, more information about the behaviour of alloying elements is needed. In this study, extruded profiles of AA6082 have been examined. Seven different alloys with increasing content of Mn have been subjected to three homogenisation procedures. The purpose of the different homogenisation procedures was to obtain different densities of dispersoids, while still maintaining the same level of elements in solid solution. The study have examined the effect of Mn and homogenisation procedure on grain structure, strength and corrosion behaviour.Results from this study showed that the density of dispersoids greatly affect the final grain structure after extrusion. Homogenisation variants that contained a high density of dispersoids showed low degree of recrystallisation. Increasing amount of Mn also contributed to a lower degree of recrystallisation. In as extruded condition variants with a high density of dipersoids were harder than variants with lower density, despite equal chemistry and elements in solid solution. At peak strength, increased content of Mn led to a reduction in strength.