Relationships between rolled grain shape, deformation bands, microstructures and recrystallization textures in Al-5%Mg

In this study, the textures and microstructures of Al-5%Mg after cold rolling 95% and recrystallization at 300 and 450 °C have been investigated. The cold rolling textures were typical but the recrystallization textures at 300 °C comprised Cube and S and at 450 °C, Cube, ND Rotated Cube plus a weak Q component. The deformed grains were wavy in the longitudinal section as a result of composite-like behaviour, and the narrowed regions had scattered orientations which weakened the final annealing texture. Another feature was grains dividing into their respective crystallographic complements. S grains frequently behaved in this way and nucleation of S-oriented recrystallized material at low temperature was common. Cube-oriented volumes were often found between complementary S volumes, and this favoured micro-growth selection and a detailed discussion of the Cube origins are given. Remarkably, recrystallization texture is largely determined by the behaviour of S- and Cube-oriented material. © 2009 Acta Materialia Inc.link_to_subscribed_fulltex

Relationships between rolled grain shape, deformation bands, microstructures and recrystallization textures in Al-5%Mg

In this study, the textures and microstructures of Al-5%Mg after cold rolling 95% and recrystallization at 300 and 450 °C have been investigated. The cold rolling textures were typical but the recrystallization textures at 300 °C comprised Cube and S and at 450 °C, Cube, ND Rotated Cube plus a weak Q component. The deformed grains were wavy in the longitudinal section as a result of composite-like behaviour, and the narrowed regions had scattered orientations which weakened the final annealing texture. Another feature was grains dividing into their respective crystallographic complements. S grains frequently behaved in this way and nucleation of S-oriented recrystallized material at low temperature was common. Cube-oriented volumes were often found between complementary S volumes, and this favoured micro-growth selection and a detailed discussion of the Cube origins are given. Remarkably, recrystallization texture is largely determined by the behaviour of S- and Cube-oriented material. © 2009 Acta Materialia Inc.link_to_subscribed_fulltex

The effects of different precipitation states on the annealing behaviour of AA6111

In this work the nucleation of the Cube recrystallised grains in AA6111 was investigated. The alloys were cold rolled to 85% and then annealed at different temperatures in an air circulation furnace. X-ray diffraction was used to obtain global textures and for specific area of interest, Electron-Back Scattered Pattern (EBSP) was used. In order to observe the microstructures after rolling and partially annealing, Scanning Electron Microscopy (SEM) was used. It was found that the recrystallisation textures are strongly related to the annealing temperature. The recrystallisation texture after low temperature annealing gives a strong retained rolling texture and at high temperature, a fairly random texture with weak Cube and rotated Cube components. The difference in the volume fraction of Cube with different alloys and annealing temperature are related to the deformation microstructures. Cube bands are observed to be deformation bands on the rolling plane. During annealing, precipitates are formed on the deformation band boundaries and Cube nuclei which are formed in the deformation Cube band are restricted to growth due to the precipitates. © (2010) Trans Tech Publications.link_to_subscribed_fulltextThe International Conference on Processing & Manufacturing of Advanced Materials: Processing, Fabrication, Properties, Applications (THERME 2009), Berlin, Germany, 25-29 August 2009. In Materials Science Forum, 2009, v. 638-642, p. 2817-282

Formation of the goss texture in a thin foil experiment on Fe-3.2%Si

Fe-3.2%Si steel from a commercial source supplied in the form of fully recrystallized sheet was selectively thinned to produce foils of different thicknesses which separated the subsurface layers in which the η texture dominated, from the central layer of γ texture. Goss oriented grains were more frequent in the subsurface layers, but were also present in the central portion of the material. Annealing these foils at ∼1000°C produced Goss texture in the surface foil, and {111 }(hkl) in the central foil. From these experiments it is clear that Goss secondaries grow easily in the η layer, but not in the γ layer and this was proved in a sequential heating experiment. A search of the misorientations between Goss oriented primary recrystallised grains in the η oriented volumes, for the most likely CSLs, i.e., Σ5 and Σ13a, proved to be unsuccessful. Some were found, but not in sufficient numbers to provide a satisfactory explanation for the formation of Goss secondaries. It is suggested however, that if CSLs are important in the selection of Goss secondaries, that Si segregation has also to be considered, for this will be less in special boundaries and thus provide less solute drag. © 2010 ISIJ.link_to_subscribed_fulltex

Relationships between cold rolling microstructures and recrystallisation textures in Al-5% Mg

Invited lectures and keynote speechesThe 11th International Conference on Aluminium Alloys, Aachen, Germany, 22-26 September 2008

Reducing cube volume in recrystallized texture by controlling the finishing temperature and rolling strain in Al-5%Mg alloy

A research programme aimed at producing weak texture in a strong work hardening alloy, Al-5%Mg has been undertaken. Two strategies are reported. In the first, the effect of hot band finishing temperature is investigated. When the temperature was high enough to produce a recrystallized hot band, subsequent cold rolling and annealing at 300 °C produced a weaker texture compared with annealing at 450 °C. A second approach involved splitting the rolling process into two parts with an intermediate anneal, with both the intermediate and final annealing temperatures as variables. The best results were obtained when the intermediate annealing temperature produced a grain size of 35 μm compared with the lower temperature of grain size 10 μm, and the final annealing temperature was low.link_to_subscribed_fulltex

Producing a random recrystallization texture in 6111 aluminum alloy

6111 Aluminium Alloy in the hot band state was cold rolled to 80% was then annealed at 450°C, 500°C and 540°C for recrystallization. The hot band was also solution heat treated, cold rolled and annealed to the same temperature to look at the difference in the recrystallization texture and precipitation states. It was found that the samples which were cold rolled and annealed without solution heat treatment gave Goss and P components after annealing. For the samples with solution heat treatment, the 450°C sample has a retained Cu type rolling texture while for the 500°C and 540°C the textures are quite random. The retained rolling texture found in the 450°C sample is due to the fact that it was partially recrystallized as the precipitates prevent complete recrystallization. The difference in the precipitation states during and after annealing of the samples with and without solution heat treatment affects the final recrystallization texture.link_to_subscribed_fulltex

Orientation imaging microscopy of the shear bands formed in Al-5%Mg alloys during cold rolling

Work done by Inagaki et al., has shown that the rolling texture of Al-Mg alloys becomes more random as Mg content increases beyond 3%, with obvious reductions in the normal FCC rolling texture components. The annealing textures were also weakened with increasing Mg contents, and this is significant because r for a random texture is 1. The alloy Al-5%Mg gave the most interesting results and so this material was selected for further research. Orientation Imaging Microscopy (OIM) has shown that the orientation{123}〈634〉 is subject to pronounced shear banding, and that the texture of the shear band material is substantially random. Shear bands are initiated at grain boundaries, and it seems, on the evidence found so far, that the neighboring grains must be crystallographically softer than the {123}〈634〉 grain through which the shear band propagates. Grains belonging to the α fiber, particularly {110}〈112〉 do not have shear bands but remain as fairly homogenous volumes devoid of obvious evidence of strain localization. The significance of this observation is discussed in the light of the necessity need for random recrystallization essential for improved drawability.link_to_subscribed_fulltex

The influence of low temperature clustering on strengthening precipitation in ams alloy

Heat-treatable 6000 series aluminum alloys are the most commonly extruded materials in the world. The precipitation process in these alloys is both complex and well characterized. The earliest clustering stage has been shown to have a large effect on subsequent strengthening precipitation, however little is known about the influence of clustering as a function of composition and processing parameters. The current work examines this influence considering the factors of relative and absolute magnesium and silicon content, and the extent of natural aging. Billets were cast and extruded prior to heat-treatment, and the hardening response was evaluated with hardness, conductivity, and transmission electron microscopy (TEM). This work advances the current understanding of Al-Mg-Si precipitation by correlating the kinetics of age hardening to composition and processing, and may lead to further optimization of 6000 series alloy strength and toughness