Influence of nodular graphite on microstructure, mechanical properties, and wear behavior of austempered ductile iron

• Increasing graphite nodule count refines nodule size and improves nodularity, enhancing mechanical properties. • G-400 (415±10 mm-2) achieves optimal tensile strength (897 MPa) and elongation (9.8%), with 5.3% and 44.1% improvements over G-200. • At high load (25 N), G-400 shows superior wear resistance, reducing worn volume by 42% compared to G-200. • Wear mechanisms identified include microcutting-dominated abrasive wear, adhesive wear, and fatigue wear.