MECHANICAL BEHAVIOUR OF NODULAR CAST IRONS AFTER PROLONGED HIGH TEMPERATURE EXPOSURE

摘要

Ductile cast irons (DI) are widely used in industrial applications for their good castability, low cost and high range of mechanical properties that can be tailored for specific applications by changing matrix microstructure. However their use is limited to components working at room temperature, since prolonged exposure at high temperature can lead to decomposition of both ausferrite and perlite, with a consequent strength reduction [1-3]. To date most of the research activity on this topic was mainly focused on investigating microstructural evolution of DIs, rather than establishing relationships among time and temperature of exposure, and final mechanical properties. The aim of the present paper was to correlate the effects of prolonged high temperature exposure on microstructure and residual strength of ductile cast irons with different matrix microstructures, after an isothermal high temperature exposure (degradation).