Microstructure engineering for superior wear and impact toughness strength of hypereutectoid powder metallurgy steel

Abstract

ABSTRACT In this study, powder metallurgical steel samples containing 1.5% C by weight were produced by sintering in a vacuum atmosphere at 1200°C. The impact test and dry sliding wear test specimens were prepared in accordance with ISO 5754 and ASTM G-99 standards, respectively. The wear and impact toughness properties of spherical cementite in the bainitic matrix (SCBM) microstructured specimens produced with different heat treatment routes were compared with pearlite plus primary cementite, fully tempered martensitic, fully bainitic and spherical cementite microstructured specimens in ferritic matrix (SCFM). Microstructural characterisations of all specimens were performed by SEM, EBSD and XRD analyses methods. Compared to fully tempered martensitic and fully bainitic microstructured specimens with similar hardness, both the dry sliding wear and the impact toughness properties of the specimens having SCBM microstructures were improved with the increased austempering time after spheroidisation treatment.