オーステンパー低合金球状黒鉛鋳鉄の破壊じん性評価

抄録

  Static and dynamic crack initiation resistance toughness (J_IC, J_Id) and crack propagation resistance toughness (J-Δa curve, T_mat) of austempered low alloy ductile iron were evaluated by direct current electrical potential method and instrumented Charpy impact test with compliance changing rate and key-curve analyses. The compliance changing rate and key-curve analyses are effective for evaluating dynamic crack initiation and propagation resistance toughness in this type of iron. QB' treatment [quenching in oil bath after holding in the γ-phase region for a short time and austempering after holding in the (α+γ) region] and B' treatment [austempering after holding in the (α+γ) region] improve crack initiation and propagation resistance toughness of Mn and Ni added iron.