Al-Ca系難燃性マグネシウム合金押出材の疲労強度特性

抄録

The objective of this research is to investigate fatigue strength characteristics in a non-combustible magnesium alloy which has relatively small amount of added elements in order to improve extrudability. Fatigue tests were performed under tension-compression loading with stress ratio, R=-1 and frequency of 150Hz at room temperature. Specimens were cut from an extruded plate in parallel (called LD material) and perpendicular (called TD material) to the extrusion direction. According to results of fatigue test, fatigue limit of LD material was slightly higher than that of TD material. Fracture surface observation indicated that fatigue crack initiated from a precipitate at specimen surface. In addition, bands-like pattern was observed on fracture surface in TD material. This pattern might be corresponding to distribution of precipitates observed in the cross section in parallel to the extrusion direction. It was considered that size and distribution of precipitates dominantly influenced on the fatigue strength of material used and induced difference in fatigue strength between LD and TD materials.