Damping Behaviour of High Silicon Nodular Cast Iron

This work focused on producing and characterizing high silicon cast irons (microstructural analysis, tensile properties, damping capacity, elastic properties). Moreover, it also evaluated the influence of RE alloying on damping capacity. The samples present a step-casting geometry to verify the cooling rate's impact on their microstructures and, consequently, on the mechanical properties. The high Si SGI presented a fully ferritic matrix (i.e. pearlite < 5%) with uniform dispersed graphite nodules; however, those also RE alloyed showed a lower nodularity. The results show an average increase, relative to the base SGI, of 33% for tensile strength and 55% for yield strength (section thicknesses between 45 and 25 mm). A damping capacity increase was observed, reaching a maximum increase of 32% with the addition of RE. The beneficial impact lies in the possibility of increasing the damping capacity of SGI, without compromising its tensile strength, by balancing the graphite degeneration (induced by RE alloying) and strengthening the ferritic matrix (promoted by the high Si content).