Mechanical components subjected to dynamic loading require materials that combine adequate strength with effective vibration-damping capability. Austempered ductile iron (ADI) is a promising candidate for such applications because of its ausferritic matrix, which provides a useful combination of strength, toughness, wear resistance, and energy dissipation. However, the damping behaviour of manganese-alloyed ADI and its dependence on austempering parameters have not been sufficiently clarified. In this study, ductile iron containing 0.3, 0.6, and 0.9 wt% Mn was austempered at 320, 370, and 420 °C for 1, 1.5, and 2 h using a full-factorial experimental design. The damping response was evaluated through impact hammer-based experimental modal analysis and correlated with hardness, ausferritic morphology, and the volume fraction of carbon-enriched/high-carbon austenite. The results showed that manganese content and austempering temperature significantly influenced the loss factor, whereas austempering time had only a minor effect within the selected range. The highest damping performance was obtained for the alloy containing 0.6 wt% Mn austempered at 370 °C, where a favourable balance was achieved between stabilized high-carbon austenite, refined ausferritic morphology, ferrite/austenite interface density, and controlled matrix hardness. At 320 °C, limited austenite stabilization restricted damping improvement, while at 420 °C, ausferritic coarsening reduced the effective interface-related energy dissipation. ANOVA confirmed manganese content and austempering temperature as the dominant factors, contributing approximately 59% and 39%, respectively, to the variation in loss factor. The regression model showed strong predictive capability within the investigated process window. Overall, the study demonstrates that damping behaviour in manganese-alloyed ADI can be effectively tailored through controlled alloy chemistry and austempering temperature, supporting its potential use in vibration-sensitive engineering components.
Poojary et al. (Sat,) studied this question.