Simple expressions to estimate the Manson–Coffin curves of ductile cast irons

• Estimation methods for strain-life curves are surveyed.
• Manson–Coffin curves of ductile cast irons are presented.
• Correlations between static and fatigue properties are proposed.
• Simple expressions to estimate the Manson–Coffin curves are proposed.

Due to the possibility of improving and adjusting their mechanical properties using austempering heat treatments, ductile cast irons are very attractive materials for structural applications. However, for this class of materials, very few fatigue data are available for designers in the International Standards. Therefore, at least in the preliminary design phase, simple expressions to estimate the fatigue properties of these materials, taking advantage of their static properties, can be useful for designers. In the recent literature, a simple method was proposed to estimate the strain-life curve of steels based only on the Brinell hardness and the elastic modulus of the material. In this paper, the possibility of extending this approach to ductile cast irons is discussed based on a set of more than 130 fatigue data obtained by the author on ferritic, pearlitic, isothermed and austempered ductile irons.