The dynamic recrystallization microstructure characteristics and the effects on static recrystallization and mechanical properties of Al-Mg-Si alloy

ABS T R A C T It is essential to clarify the dynamic recrystallization microstructure characteristics of age-hardened aluminum alloys and the effects on the static recrystallization microstructure and aging mechanical properties, with the aim of selecting the deformation conditions reasonably. This work investigated the evolution of the hot deformation and solid solution microstructures and aging mechanical properties of Al-Mg-Si alloy with deformation temperatures of 400-550 degrees C, strain rates of 0.01-10 s - 1 , and true strains of 0.2-0.8. Research has shown that it is advantageous for the DDRX and CDRX mechanisms to annihilate and rearrange dislocations simultaneously for forming deformation microstructure with uniform grain size at higher deformation temperatures and lower strain rates (such as 500 degrees C, 0.01 s - 1 ). Additionally, the lower dislocation density in deformation microstructure facilitated the inhibition of static recrystallization during subsequent solid solution treatment, whereas lower deformation temperature and higher strain rate conditions should result in a greater degree of static recrystallization and reduce the uniformity of the solid solution microstructure. Hardness test results demonstrated that the deformation temperature of 480-520 degrees C and strain rate of 0.03-0.2 s - 1 were the appropriate conditions for Al-Mg-Si alloy to attain finer and uniform grains and superior properties after solid solution treatment. The extruded samples within the above conditions (500 degrees C, 0.032 s - 1 ) exhibited higher UTS and YS after solid solution and aging treatment, reaching 444 +/- 2 MPa and 426 +/- 4 MPa, respectively.