2022-08-17T08:07:22Zhttps://niigata-u.repo.nii.ac.jp/oaioai:niigata-u.repo.nii.ac.jp:000036972021-03-01T20:03:05ZQuantitative Evaluation of Effects of Nonmetallic Inclusions on Fatigue Strength of High Strength Steel高強度鋼の疲労強度に及ぼす介在物の影響の定量的評価法高強度鋼の疲労強度に及ぼす介在物の影響の定量的評価法村上, 敬宣44750児玉, 昭太郎44751小沼, 静代44752FatigueInclusionsSmall CracksDefectsHigh Strength SteelsVickers HardnessThreshold Stress Intensity Factor RangeFish EyeCleanlinessFatigue LimitFirst, the effects of nonmetallic inclusions on the fatique strength of metals are reviewed and the influential factors are revealed. Next, it is emphasized that the effects of nonmetallic inclusions must be analyzed from the viewpoint of small defects or small cracks, because the threshold condition at the fatigue limit is not the condition for crack initiation but the condition for the non-propagation of a crack emanating from defects or inclusions. Finally. from this point of view, the equation for the prediction of the threshold stress intensity factor range ΔK_<th> and fatigue limit σw for defects and small cracks was applied to predict those for inclusions contained in high strength steels. It is demonstrated that the square root of the projected area of inclusions and the H_v of the matrix are the crucial parameters to predict the fatigue limit of metals containing inclusions. The predictions by the proposed equations were in very good agreement with the experimental results obtained from the fracture surface showing fish-eye patterns. The reasons why the fatigue limit σw of high strength steels does not increase linearly with increasing hardness, and why the scatters of fatigue limit are so large are made clear.journal article日本機械学会1988-04application/pdf日本機械学会論文集. A編50054688696日本機械学会論文集. A編AN0018742X03875008https://niigata-u.repo.nii.ac.jp/record/3697/files/87-0320A.pdfjpnhttp://ci.nii.ac.jp/naid/110002377578日本機械学会本文データは学会の許諾に基づくCiNiiからの複製である