Elastic modulus and continuous yielding behaviour of ferritic spheroidal graphite cast iron

Abstract

he initiation and extension of slip lines and the microscopic yielding behaviour have been investigated in tensile deformation of as cast and prestrained ferrite spheroidal graphite cast irons. Slip lines were observed at a small strain of 0·36% and cracks appeared in the graphite nodules before a strain of 0·71%. This suggests that microscopic yielding had occurred and that the dynamic continuity between the graphite nodules and the matrix was diminished during the initial stages of deformation before macroscopic yielding. The values of Young's modulus of the graphite nodules and the ferrite matrix were estimated to be 300 and 180 GN m⁻², respectively. The continuous yielding behaviour is attributed to the graphite nodules acting as initiation sites of plastic deformation.

MST/1507