Effect of Crack Source Location on High Cycle Fatigue Life of 6005A Aluminum Alloy Extruded Profiles

The effect of crack source location on high cycle fatigue life of 6005A-T6 aluminum alloy extruded profiles was studied by high cycle fatigue tests. The results show that the median fatigue strength of 6005A-T6 aluminum alloy extruded profiles was 164.5 MPa at the stress ratio of 0.1; the fatigue strength was relatively high, but the fatigue life distribution was relatively dispersal. Under the maximum stress of 200 MPa, the fatigue crack source region of samples with different fatigue lives was small; the fatigue crack propagation region consisted of fatigue strips and secondary cracks; the area of transient fracture region was large, and the region consisted of holes and dimples. The main reason for the difference in fatigue life under the same maximum stress was the difference location of fatigue crack source. Under the maximum stress of 200 MPa, the fatigue life of the sample with fatigue crack source in holes was the longest, which was one order of magnitude larger than that with fatigue crack source on oxide inclusions, and the fatigue life of the sample with the fatigue crack source in Al₇(CrFe) second phase particles was between the two.