基地組織の異なる球状黒鉛鋳鉄の引張変形特性に及ぼす黒鉛組織の影響に関する定量的解析

抄録

  Tensile flow stress of spheroidal graphite cast iron (σ_z) was expressed well by the following equation, as the function of graphite area fraction (A_g) and the average grain size (D) : σ_z = (1−k₁A_g) (σ₀ + k₂D^−1/2)
Values of k₁, σ₀ and k₂ have been investigated by varying matrix structure and graphite area fraction. In this study, k₁ value was noteworthy after a series of analysis, those were showing a similar value about 2.0-2.5. It implys that the tensile flow stress of spheroidal graphite cast iron is not only received the influence of the matrix structure, but also influenced by the dynamical factor of which developing in the matrix during tensile deformation. Moreover, the tensile flow stress even if extremly influenced by the matrix structure and graphite area fraction, but the significant change of k₁ value could not be recognized, except the specimens of CV graphite cast iron. Also, the markable variation of k₁ value was shown by lowering the graphite nodularity. It is suggested that the effect of stress concentration around the front tip of the graphite particles is a dominating factor in the k₁ value associated with that of the tensile flow stress.