ADI の引張特性及び疲れ強度に及ぼす黒鉛粒径及びオーステンパ処理条件の影響

抄録

  In order to clarify the effects of graphite nodule size and austempering conditions on tensile properties and fatigue strength of ADI, tensile tests and fatigue tests under completely reversed plane bending condition were carried out. It is observed that the austempering at 648 K for 3.6 ks is the best treatment condition for elongation and strength of the iron. Tensile strength decreases somewhat and elongation decreases a lot with the increase of graphite nodule diameter. The fatigue limit of ADI is strongly dependent on graphite nodule diameter, it linearly increases with the decrease of diameter on the logarithmic scales. The fatigue limit can be more accurately predicted by the equation : σ_w=1348/d_max^0.29 (γ=0.97). Therefore, it is most effective to reduce the graphite nodule diameter as much as possible in order to improve tensile properties and fatigue strength of ADI.