Abstract
Fatigue fracture behavior of magnesium single crystals containing cracks growing in different crystallographic orientations has been investigated. To investigate fatigue fracture behavior of small single crystals, plain bending fatigue test method for thin sheet specimen was developed. In A-specimen, the surface plane and the loading direction are (0001) and [1120], respectively, a fatigue crack propagates along [1100] at higher stress level while a crack propagates [1210] at lower stress level. In C-specimen, the surface and the loading direction are (1120) and [1100], respectively, a crack propagates partially along {1012} twin interface. In D-specimen, the surface and the loading direction are (1100) and [1120], respectively, a crack propagates along {1012} twin interface at higher stress level while a crack propagates along [0001] at lower stress level. As a result, S-N curves of each specimen showed orientation dependence. Fatigue strength of C-specimen is higher than that of A- and D-specimen. We also discuss the fatigue behavior mechanism of magnesium single crystals.
