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Hot tensile tests have been performed on AA7075 aluminum alloy to investigate the effects of temperature and strain rate on its deformation behavior during the hot stamping-quenching process. The corresponding mechanical properties and associated microstructures have also been studied. The results indicate that the flow behavior curves exhibit work hardening, a dynamic equilibrium, then a dramatic decrease, ultimately leading to fracture. Ductility of over 30% can be obtained at relatively low deformation temperature and strain rate. The fracture mechanism changes from ductile transgranular fracture to ductile intergranular fracture owing to the weakening of the grain-boundary strength at high temperatures. The strength of the tested samples after artificial aging treatment increases with the deformation temperature after solid-solution heat treatment. It is more appropriate to choose a temperature of 400°C and a strain rate of 0.1–1 s−1 for AA7075 aluminum alloy parts to simultaneously obtain the desired ductility and final strength in this process. [ABSTRACT FROM AUTHOR]

Al-Ti-C master alloys were fabricated by using aluminum melt reaction method with graphite powders (GPs) or carbon nanotubes (CNTs) as carbon source. The microstructure formation during the reaction process was analyzed. The α-Al grain refinement abilities of the master alloys were checked. The results demonstrate that the TiC particles form mainly through the reaction between the solid C (GPs or CNTs) and the solute Ti. Using CNTs as the carbon source can significantly enhance the recovery rate of carbon and promote the formation of Al-Ti-C master alloy with a well dispersed microstructure and high α-Al grain refining ability. [ABSTRACT FROM AUTHOR]

Recently, an efficient integrated forging process has been proposed in which solutionized aluminum alloy extruded bars are directly hot forged and quenched. In this study, the hot deformation behaviors and microstructure evolution of 6082 aluminum alloy extruded bar was investigated via isothermal compression tests under the temperature range of 400–535 ℃ and strain rates range of 0.1–10 s−1 with different strains. The deformation behaviors were described by the established strain-compensated constitutive model and processing maps. The microstructure evolution of the deformed specimens was revealed by electron back scattered diffraction (EBSD) and transmission electron microscopy (TEM). It was found that the Zener-Hollomon (Z) parameter, which involved temperature and strain rate, exerted a considerable influence on the deformation behaviors and microstructure evolution. Deformation-induced extensive dislocations were pinned by the dispersoids and generated cellular substructures under high ln Z (i.e. low temperature or high strain rate), potentially triggering dynamic instability. The tangled dislocations pinned by the insoluble dispersoids continued to overcome the pinning points as ln Z decreased, while the dislocations were consumed by the rotation of subgrain boundaries. As a result, the geometrically necessary dislocation (GND) was decreased with the significant increase of the fraction of high angle grain boundaries (HAGBs). In addition, the stable-end orientations, namely, Brass {011}< 211 > and Goss {011}< 001 > texture components with high Schmid Factors (SFs) are generated during compression, facilitating the dislocation movement and thus promoting the fraction of recrystallization. The above findings demonstrate the foundation for improving forming performance and optimizing the processing parameters for the integrated forging process. • The flow behaviors of solutionzied 6082 aluminum alloy extruded bars were investigated. • The relationship of the dominant softening mechanisms and the Z parameter was revealed. • Evolution of grain boundaries misorientation and geometrically necessary dislocation was illustrated. • The characteristics of grain orientation and Schmid Factors were investigated. [ABSTRACT FROM AUTHOR]