Two Ti-6Al-6V-2Sn alloys, with globular and lamellar microstructures, are deformed at 750°C during tensile and compression tests. The lamellar microstructure shows softening and higher peak stress values than the globular microstructure as a consequence of the Hall-Petch effect. In-situ high energy synchrotron diffraction experiments allow characterization of the load partition between αand β-phases, plastic deformation mechanisms and texture evolution. The α-phase deforms mainly by rotation while the β-phase deforms by misorientation formation, acting merely as load transfer agent. The Taylor factor evolution of the α-phase and the annihilation of dislocations are analyzed qualitatively and quantitatively. The Taylor factor is connected to both the softening observed in the alloy with the lamellar microstructure and the texture development.

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Most commercial aluminum alloys are characterized by dynamic recrystallization at very large deformations in a continuous manner. The present study deals with the characterization and modeling of the evolution of the microstructure of an aluminum wrought alloy at large plastic deformations. Hot torsion tests of the AA6082 aluminum alloy are carried out using the thermomechanical simulator Gleeble®3800 in a wide range of temperatures and strain rates. The use of water quenching immediately after deformation avoids any static restoration during cooling. Microstructural investigations are carried out by means of electron back scattered diffraction using a scanning electron microscope to determine the grain and subgrain structures, as well as the misorientation distributions. In-situ synchrotron radiation tests during hot torsion are used to confirm the continuous dynamic recrystallization (CDRX) by the evidence of the conversion of low angle boundaries (LAGBs) into high-angle boundaries (HAGBs) and the formation of new texture. Experimental investigations show that CDRX starts with the formation of LAGBs at low strains (center of the sample). By subsequent straining (close to the surface of the sample), the accumulation of dislocations at the LAGBs causes an increase in their misorientation until a critical value is reached and LAGBs transforms into HAGBs. The developed model consists of a microstructural model, equation rates and constitutive equations. The microstructure is described by three internal variables. Their rates are evaluated using the Kocks-Mecking model. The modelled and experimental flow stresses show softening due to the consumption of dislocations and the continuous formation of new HAGBs.