Effect of Microstructure on Deformation and Fracture of Thixomolded and Thermomechanically Processed AZ61

This paper investigates the deformation, damage accumulation and fracture behavior of fine-grained AZ61 sheet produced by combined Thixomolding and Thermomechanical (TTMP) processing. In the TTMP process, warm rolling of a fine-grained, untextured Thixomolded plate with subsequent recrystallizion produces a sheet with an α-Mg grain size of 3 to 5 μm and s-particles with an average diameter of 0.5 μm. The fine grain size and weak texture in the sheet results in nearly isotropic mechanical properties. Damage during tensile straining occurs in the form of cracking in the s-particles in both the as-Thixomolded plate precursor and in the recrystallized sheet. However, the material fails due to strain localization in shear bands and microvoid coalescence.