2033 SNCM439鋼の超高サイクル域における軸荷重疲労強度特性(S11-2 軸荷重下の超高サイクル疲労特性,S11 金属材料の超高サイクル疲労特性の解明)

概要

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To investigate the S-N characteristic and fatigue properties of high strength steels in very high cycle regime, axial loading fatigue tests were carried out using the hour-glass shaped specimen of Ni-Cr-Mo steel, SNCM439, under the stress ratio of -1 in air at room temperature. From the experimental result, duplex S-N curve, composed with surface inclusion induced S-N curve and subsurface inclusion induced one, clearly appeared. The granular bright facet (GBF) area was observed in the vicinity of the inclusion of subsurface fracture origin. It was expected from the discussion based on the fracture mechanics that threshold stress intensity factor range of surface inclusion was small compared with that of subsurface inclusion, because of difference in an environmental condition surrounding the inclusion.
2007-09-07