HY140およびHY180鋼における切欠きからの疲労割れ発生および初期伝ぱ挙動

概要

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The behavior of fatigue crack initiation and propagation from the notch tip with the notch radius of 0.10 mm was examined in plate test pieces of HY140 and HY180 steels. Fatigue tests were done in air at the tension-to-tension, tension-to-compression, and compression-to-compression, respectively. The results are as follows ; (1) The macroscopic crack growth rate da/dN does not change extremely with the crack length from the notch tip ai when a_i is smaller than the cyclic plastic deformation zone size r_<N.P.C.> (2) Cycles and da/dN at the crack length of 0.030 mm ((N) 0.03 and (da/dN)_< 0.03>) are determined by r_<N.P.C.> (3) The da/dN decreases with an increase of a_i due to residual stress in the monotonic plastic deformation zone at the notch tip which exists prior to crack initiation, when R<-1. (4) The da/dN increases rapidly with ai due to residual stress a_i the notch tip, when R>-1. (5) The da/dN does not correspond to the striation spacing (da/dN)_<S.P> in the area in which the behavior of crack growth is controlled by the plastic deformation zone at the notch tip. (6) The da/dN coincides with the (da/dN)_<S.P> and is a function of ΔK^2 in the area in which the behavior of crack growth is not controlled by the plastic deformation zone at the notch tip.
社団法人日本材料学会の論文
1977-06-15