대칭위치에 존재하는 미소원공결함의 깊이변화가 SM20C의 피로균열거동에 미치는 영향

The Effect of Fatigue Crack Behavior on the Variable Depth of Micro Hole Defects in SM20C at the Symmetric Position

The main objective of this study is to consider the effect of fatigue crack behavior on the variable depth of micro hole defects in SM20C at the symmetric position. The fatigue crack propagation test is performed by rotary bending fatigue test machine. The relationship between crack length(2a), cycles(N) and crack growth rate(da/dN) are investigated in this study. The result from the rotary bending fatigue test under the applied stress at 250MPa turned out that the fatigue life illustrated almost constant when the depth of symmetric micro hole deflects is both part A and B at the hope depth(h) = 0.5mm.