Theoretical Estimation to the Cyclic Strength Coefficient and the Cyclic Strain-Hardening Exponent for Metallic Materials: Preliminary Study

The ultimate purpose of the present article is to theoretically estimate the cyclic strength coefficient and the cyclic strain-hardening exponent. For this purpose, the performance parameters of 22 alloys were examined and equations that relate the cyclic strength coefficient and the cyclic strain-hardening exponent to the monotonic tensile ones were developed. Then, by using formulas that express the strength coefficient and the strain-hardening exponent through the four conventional tensile performance parameters, i.e., the yield strength, the ultimate tensile strength, the fracture strength, and the fracture ductility, expressions that describe the cyclic strength coefficient and the cyclic strain-hardening exponent are established. By means of cyclic stress-strain curve, the limitations of the traditional methods of estimating the cyclic strength coefficient and the cyclic strain-hardening exponent are pointed out, and the ability of the new equations at describing the process are established. From the equations the cyclic strength coefficient and the cyclic strain-hardening exponent can be theoretically estimated using the monotonic ones. Furthermore, in the absence of the strength coefficient and the strain-hardening exponent, the cyclic ones can still be obtained from the expressions using the four conventional tensile performance parameters.