鋳造アルミニウム合金の超高サイクル疲労特性と損傷機構

抄録

In this study, cantilever type rotating bending fatigue test and axial force fatigue test were carried out for the cast aluminum alloy. Three kinds of materials with different manufacturing time were prepared. The very high cycle fatigue properties and damage mechanism were investigated. As the result of the micro Vickers hardness tests, it was found that the hardness has the tendency to increase from the inside of the test specimen toward the surface. As the results of cantilever type rotating bending fatigue test, the test specimen were fractured over 1×10⁸ cycles, the S-N curve showed a tendency specific to non-ferrous metals that did not show a clear fatigue limit. The fatigue strength of the cantilever type rotating bending fatigue test was higher than that of the axial fatigue test. The fatigue crack origin was mostly a casting defect. The positions of the crack origin were a surface or close to surface. √area were almost 100 μm or less. There was no clear correlation between √area and the number of cycles to failure. It was found that √area follows a Gumbel distribution. As a result of estimating the time strength at 107 cycles using the fatigue limit estimation formula, the estimated value was close to the experimental value.