Push-pull fatigue tests on ductile and vermicular cast irons

Abstract

This article aims at measuring and comparing the fatigue strength with fully reversed push-pull tests in the case of two different cast irons: ductile and vermicular. Spheroidal Graphite Iron (SGI), also known as ductile cast iron, is nowadays used in a very large variety of applications. It represents a valid option when strength and stiffness are required, namely, when high values of tensile strength and Young’s modulus are coupled with appreciable deformation before failure. By contrast, a different cast iron, known as Compacted Graphite Iron (CGI) or vermicular cast iron, presents its benefits in replacing SGI with respect to specific applications. In particular, with better castability, machinability and thermal resistance, SGI is ideal when components suffer simultaneous mechanical and thermal loadings, such as cylinder blocks and heads. While SGI benefits of a wide scientific literature, CGI is a relatively unknown material, especially referring to its response under fatigue loads.