Cyclic Crack Resistance of High-Strength Cast Irons at the Stages of Initiation and Growth of a Macrocrack

On investigating high-strength cast irons of the austenitic, ferritic, and pearlite-ferritic classes, we have experimentally corroborated that the relations Δy* vs. Ni, d* vs. Ni, and Δε* vs. Ni obtained at the stage of initiation of a fatigue macrocrack in air and a corrosive medium (3.5% NaCl solution) can be transformed into the relations da/dN vs. ΔK and da/dN vs. Δε*. The latter describe the stage of macrocrack propagation within the framework of the force and strain approaches, respectively. We have shown that the strain parameters, as compared with the force ones, are 1.5–2 times more sensitive to the influence of a corrosive medium on the cyclic crack resistance of high-strength cast irons.