Influence of section size on dual phase ADI microstructure and properties: Comparison with fully ferritic and fully ausferritic matrices

Abstract

The present work aims to evaluate and compare the influence that section size has on the microstructure and properties of fully ferritic, fully ausferritic and dual phase ADI matrices. Samples taken from 'Y' blocks of 25, 50 and 75 mm thickness were used to perform metallographic studies and mechanical tests. Cooling rate differences arising from changes in section size promote different microsegregation characteristics affecting solid state transformations and, consequently, the final microstructure and properties. When the section size increases, some properties decrease. The strongest deleterious effect was ascribed to the elongation and impact of ADI samples, where drops of nearly 40% were reached when specimens taken from the thinnest 'Y' blocks were compared to those taken from the thickest ones. Regarding fracture toughness, ferritic matrices exhibited the most noticeable detrimental effect. Dual phase ADI samples, on the other hand, presented the least deleterious section size effect on all the studied properties. © 2009 Institute of Materials, Minerals and Mining.