Influence of solidification defects and degenerate graphite on the static mechanical properties of heavy-section EN-GJS-400-15 ferritic ductile iron castings

Excellent castability and mechanical properties have led ductile irons to gain increasing importance in the heavy-duty transport and renewable energy sectors. Long solidification times involving heavy-section castings can lead to degeneration of graphite spheroids and the formation of solidification defects, negatively affecting their mechanical properties. In this study, the effects of long solidification times (from 3 to 20 h) were investigated in different zones of cubes with sides of (i) 350 mm, (ii) 700 mm and (iii) 1000 mm. An important decrease in mechanical properties was observed with increasing solidification times, attributable to solidification defects and degenerative phenomena affecting graphite spheroids. These results are of great relevance to evaluate the mechanical behavior and failure mechanisms heavy-section ductile iron castings of non-standard dimensions in relation to the different solidification conditions occurring inside them.