Akademik Veri Yönetim Sistemi
MATERIALPRUEFUNG/MATERIALS TESTING, cilt.66, sa.12, ss.1-12, 2024 (SCI-Expanded)
: This study investigates the effect of the austempering temperatures on the microstructures and mechanical properties of austempered ductile iron with dual-matrix structure (DMS-ADI). An unalloyed ferritic ductile iron bar samples were intercritically austenitized at 810 °C for 60 min and austempered at different austempering temperatures (300 °C, 325 °C, 350 °C, and 375 °C) for 120 min. Microstructural and mechanical characterization were examined using optical microscopes, scanning electron microscopes (SEM), X-ray diffraction (XRD) analyses, hardness, and tensile tests. Experimental results showed that the DMS-ADI samples exhibit a dual-phase structure consisting of proeutectoid ferrite + ausferrite structures. The volume fraction of ausferrite (42.5–47.5 %) was almost stable in all austempering temperatures in DMS-ADI samples. The high-carbon retained austenite volume fraction, and its carbon content increased with increased austempering temperatures. At austempering temperatures up to 350 °C, strength and hardness increased, while energy at break and total elongation decreased. The strength and hardness decreased, while energy at break and total elongation increased at 375 °C austempering temperature. All DMS-ADI samples exhibited ductile fracture surfaces except for those austempered at 350 °C. The highest (σUTS = 590 MPa and εT = 18.8 %) and lowest (σUTS = 434 MPa and εT = 28.5 %) mechanical properties were obtained in DMS-ADI samples austempered at 350 °C and 300 °C, respectively