Fatigue is the primary reason for the failure of structural components. Resistivity ofa coarse grain heat affected zone against fatigue crack initiation in presence of micro-defectsis discussed in the present article. Samples of material with a martensitic coarse grain heataffected zone microstructure were prepared by proper thermal treatments. Microstructurallysmall holes were used as artificial micro-defects. They were created by drilling. Compressiveresidual stresses appear in the material due to the irreversibility of plastic deformation.Moment of hole drilling enables to prepare samples with and without effects of residualstresses. Critical stress level for fatigue crack initiation depends on the actual size of the hole.The location and the way of crack initiation is affected by the presence and character ofresidual stresses.
展开▼
