炭素鋼の切欠材の疲労強度に及ぼすフェライト・パーライト組織の影響

概要

論文の詳細を見る
Rotating bending fatigue tests were carried out on the circumferential notched specimen of three kinds of carbon steel with nearly equal ferrite grain sizes of 20μm but different volume fractions of pearlite. Fatigue tests were also carried out for 0.15% carbon steel with ferrite grain size of 50μm and 0.45% carbon steel with ferrite grain size of 5μm. The effect of microstructures on the fatigue strengths σ_<ws> (the limit stress for slip band), σ_<w1> (the limit stress for macrocrack initiation), and σ_<w2> (the limit stress for fracture) is discussed by comparing these values between three kinds of carbon steel. The main results are as follows : (1) Since σ_<ws> is localized to a highly specified region, variation of K_tσ_<ws> is small irrespective of notch root radius. (2) If the grain size of ferrite is nearly equal, variation of σ_<w1> is small irrespective of pearlite volume fraction under the certain amount of pearlite. (3) In medium carbon steel, σ_<w2> increases with increasing grain size of ferrite. (4) Notch root radius at the branch point ρ_o varies with the grain size of ferrite.
1994-07-25