Other studies compared the strain rate sensitivity of conventional grain sized and ultra-fine grain sized Al 6061 as function of temperature and proved that strain rate sensitivity increases as temperature rises but this dependence is more pronounced for ultra-fine grain alloys. Ultra-fine grain aluminium alloys have high strain rate sensitivity even at low strain rates because of grain boundary sliding compared to coarse-grained alloys. For other aluminium alloys, the strain rate sensitivity was found to increase with augmentation of dislocation density and thus of plastic strain. For the 7056 alloy, the increase of m as function of temperature for compression loads depends on the temper state of the alloy. The strain rate sensitivity value for AlвЂ“Mg alloys in uniaxial tension was found to increase up to 0.4 at a temperature of 300 вЊ. Positive values of strain rate sensitivity as function of strain rate from 10 в€’4 s в€’1 to 1 s в€’1 were measured for aluminium alloys AA1200 and AA3103, while negative values of m in AlвЂ“Mg alloys at room temperature are attributed to dynamic strain ageing caused by interaction of Mg atoms with dislocations. During forming, a positive value of m is beneficial to delay strain localization, on the contrary, a negative value will localize early plastic flow. During hot deformation, when thermal activation of dislocation glide becomes important, the flow stress of the material is both temperature and strain rate dependent and for several metals, the strain rate sensitivity increases as the deformation temperature approaches the melting temperature. Depending on composition and heat treatment history, during cold deformation, aluminium alloys can exhibit positive or negative strain rate sensitivity depending on strain rate. temperature and strain rate) and intrinsic effects (e.g. the value of strain rate sensitivity for an alloy depends both on extrinsic effects (e.g. The strain rate sensitivity ( m) is a material parameter describing the variation of flow stress under a change of strain rate and it depends both on temperature and strain rate of deformation. During hot rolling, high values of strain rate sensitivity contribute to Cube stabilization and promote formation of Copper texture and delay Brass and S.Д¬ube texture evolution in aluminium alloys is considered with special attention because of its preferential growth during the recrystallization heat treatment of cold rolled aluminium sheets causing anisotropy responsible for forming defects during deep-drawing. Further crystal plasticity simulations were performed to predict the influence of strain rate sensitivity during several hot rolling conditions where activity of non-octahedral slip systems was included in the simulations. The results found in cold rolling crystal plasticity simulations were compared with experimentally determined Cube distribution and texture components obtained through thickness for Al6016 rolled at 80 m/min and 600 m/min. Recrystallization texture components (P, Q) are not affected by strain rate sensitivity, while the invGoss fraction decreases for high values of strain rate sensitivity. The final volume fraction of Goss is highest when the strain rate sensitivity is 10 в€’2 but low if the strain rate sensitivity is 10 в€’3 or raises up to 10 в€’1.

The Copper volume fraction in the final texture diminishes as the strain rate sensitivity decreases, while Brass and S components of the beta fiber show a moderately higher volume fraction when the strain rate sensitivity increases. Other texture components are affected by changes in strain rate sensitivity as well.

High values of strain-rate sensitivity cause formation of Cube transition bands leaving thin Cube grains in the microstructure and delay their fragmentation. It is found, that low values of strain rate sensitivity promote Cube grains fragmentation and avoid formation of transition bands already at 50 to 55 pct thickness reduction. Therefore, crystal plasticity simulations and experiments were performed up to 73 pct of thickness reduction for cold rolling on Al 6016. The influence of strain rate sensitivity on development of Cube texture and on the morphology of Cube-oriented grains is often neglected in simulations approaches.

Coppercube change loading texture