The effect of microtexture evaluated by electron backscatter diffraction method on fatigue crack propagation behaviour in rolled copper film

摘要

Using a fatigue-testing method by which a fatigue crack can be propagated in a film adhered to cover an elliptical through-hole in a base plate, annealed rolled copper films have been fatigued. The effects of rolling textures and annealing twin boundaries on fatigue crack propagation behaviour are discussed. The fatigue crack propagates in a large zigzag pattern in the TC specimen (crack perpendicular to the rolling direction), while the crack propagation path in the RC specimen (crack parallel to the rolling direction) is nearly straight. Further, the fatigue cracks propagate slower toward the perpendicular direction than toward the parallel direction. After fatigue testing, the crystallographic characteristic of rolling textures around the fatigue crack in the annealed film is analysed using the EBSD (electron backscatter diffraction) system. Because the annealing twin boundary is in the same plane as the slip of the face-centred-cubic metal, the fatigue crack tends to propagate along the slip line initiated along the annealing twin boundary.