Effect of deformation structure on fatigue behavior of an Al-Mg-Sc alloy

Effect of initial grain size on fatigue behavior of an Al-6%Mg-0.35%Mn-0.2%Sc- 0.08%Zr-0.07%Cr alloy was examined. The initial CG microstructure with an average grain size of ~ 22 μm was manufactured by casting followed by solution treatment at 360 °C for 12 h. To produce the UFG condition, the alloy was subjected to equal-channel angular pressing (ECAP) at 320 °C up to a total strain of ~ 14. Extensive grain refinement provided the formation of fully recrystallized structure with an average grain size of 700 nm. It was shown that the formation of UFG structure provided +60% increases in yield stress and +25% increases in fatigue strength. Fundamentals of this effect of microstructure on the static strength, fatigue resistance and fracture modes are discussed.