Influence of Tensile Fatigue Load on Hole Wall Strength of Parts with Hole

Further research was performed to find out the causes of fatigue fracture from the perspective of hole wall strength change under tensile load; test data were analyzed based on the tested microhardness and residual stress, combined with the finite element simulation result. The analysis results show that the fatigue fracture samples present microhardness gradient. The hole wall surface of length direction has maximum hardness; the hole wall subsurface of width direction has maximum hardness. The effect of cyclic plastic stress on the hole wall differs with the change of position of the hole wall. The hole wall of width direction presents strain hardening first and then cyclic softening, and thus becomes the weak area. Different position of hole wall has different tangential residual stress field distribution. The hole wall surface of length direction has maximum residual compressive stress; the hole wall subsurface of width direction has maximum residual compressive stress. The hole wall surface of width direction becomes the weak area, resulting from stress concentration effect.