The Effect Of Deep Rollıng Process Parameters On Subsurface Hardness Dıstrıbutıon In Deep Rollıng Of En Aw6061 Alumınıum Alloys

Abstract

Aluminium and aluminium alloys are widely used in production of electrical conductors, owing to their mechanical strength and electrical conductivity properties. Also, aluminium is cheaper and lighter than copper. Thus, it is advantageous to use aluminium conductors in areas where high volumes of conductors are used. However, its electrical conductivity is lower than copper and this causes losses in transmission of electricity. Therefore, producing conductors that have both high mechanical strength and high electrical conductivity has always been an important topic and took place in many studies.

In recent studies, it is shown that together with appropriate heat-treatments ultra-fine-grained alloys can reveal high strength and high conductivity together. In order to obtain ultra-fine-grained alloys, many different severe plastic deformation methods can be used. However, these methods are not suitable for continuous production lines and not yet commercialized and yield high costs. On the other hand, deep rolling is a method used for years, that can alter the microstructure at the surface and subsurface area of a component by plastic deformation. In addition, it has low tooling and operating costs and can be modified to suit in continuous production lines. Because of these features, deep rolling can be convenient to be used in production of such conductors. Therefore, such a study was carried out to understand how parameters of deep rolling effect certain properties of an aluminium alloy.

In this study, the effect of deep rolling force on work-hardening state and surface roughness at the surface and subsurface area of a component made of differently tempered EN AW6061 aluminium alloy is investigated. The study was carried out in two parts which are experimental work and numerical simulation part. According to the results, high forces provided increase in hardness values at layers deeper than 2 mm for T4 tempered material. Also, increase in hardness values can go up to 60% for T4 tempered material. However, for T6 tempered material, increase in hardness values was obtained only at highest rolling force and no hardness increase was observed at layers deeper than 0.1 mm. In conclusion, the predictions obtained from numerical simulations, hardness distributions and surface roughness results were evaluated and discussed together.