JOURNAL OF POLYTECHNIC-POLITEKNIK DERGISI, no.3, pp.1225-1234, 2022 (ESCI)
In this study, the correlations among martensite volume fraction-mechanical properties-dislocation density was investigated in dual-phase (alpha+M) ductile cast irons (DP-DCI). Dual-phase microstructures consisting of martensite and proeutectoid ferrite in different phase volume fractions were produced by cooling in the water at room temperature from 770 degrees C, 775 degrees C, and 780 degrees C intercritical austenitizing temperatures. Microstructure characterization studies were performed using an optical microscope, scanning electron microscope (SEM), and X-ray diffraction (XRD) analysis techniques. Tensile and hardness tests have been conducted to determine the mechanical properties. Dislocation density was calculated via Williamson-Hall (W-H) equation by using XRD patterns. It was determined martensite volume fraction and dislocation density enhanced with increasing intercritical austenitizing temperature. As the martensite volume fraction increased, that the hardness, yield, and tensile strength increased, the total % elongation decreased and the fracture mode changed from ductile to brittle were observed.