Effect of carbon content and ferrite grain size on the tensile flow stress of ferritic spheroidal graphite cast iron

The effects of varying carbon content and ferrite grain size on the tensile flow stress of ferritic spheroidal graphite cast iron have been investigated. The flow stress of this material can be expressed by the following equation as a function of graphite volume fraction (V_g) and ferrite grain size (d_f) without an influence of graphite nodule diameter: Φ = K₃(l - k₁V_g)({Φ₀} + k₂d_f). The relationship between tensile stress (Φ) and the volume fraction of graphite (V_g) obtained by the analysis of plastic deformation can be approximated by the above equation. It is apparent from the results that the flow stress of ferritic spheroidal graphite cast iron is influenced appreciably by ferrite grain size and the triaxial stress field developed in the ferrite matrix between graphite nodules.