The Effect of Strain on the Development of Ultra-Fine Grain Structure in 7055 Aluminium Alloy Processed by Equal Channel Angular Extrusion

Ilya Nikulin; Yoshinobu Motohashi; Rustam Kaibyshev

doi:10.4028/www.scientific.net/MSF.584-586.691

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Combining Equal-Channel Angular Extrusion (ECAE) and Heat Treatment for Achieving High Strength and Moderate Ductility in an Al-Cu Alloy
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The Effect of Strain on the Development of Ultra-Fine Grain Structure in 7055 Aluminium Alloy Processed by Equal Channel Angular Extrusion
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Investigations on Deformation Behavior and Microstructure of Ultrafine Grained Two Phase Al-Mn Alloy Fabricated by Confined Channel Die Pressing
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The Effect of Strain on the Development of Ultra-Fine Grain Structure in 7055 Aluminium Alloy Processed by Equal Channel Angular Extrusion

Abstract:

Grain refinement taking place in a commercial 7055 aluminum alloy under equal channel angular extrusion at a temperature of 250°C, was examined. The material was deformed up to a total strain, ε, of ~12. At ε≈1, the development of subgrain bands was found. Upon further straining the average misorientation of deformation-induced boundaries increases; low-angle grain boundaries (LAGBs) gradually convert into true high-angle grain boundaries (≥15°) (HAGBs). At ε≈4, a structure consisting of boundaries with low and high angle misorientations was observed. At ε≈12, a structure with an average grain size of ∼0.7 µm was formed. This size is roughly similar to that for subgrains developed at preceding strains. It was shown that the formation of submicrocrystalline grains occurs through continuous dynamic recrystallization both along initial boundaries and within interiors of original grains as well.