AbstractUltimate tensile strength, 0·2% proof strength, elongation, and impact energy measurements are reported for an alloyed ductile iron of composition (wt-%) Fe–3·49C–2·33Si–0·42Mn–0·25Cu–0·23Mo–0·035Mg for austempering temperatures of 400, 375, and 350°C and a range of austempering times after austenitising at 920°C for 120 min. The ADI ASTM A897M:1990 standard is satisfied for an austempering temperature of 350°C but not at 375 or 400°C. This behaviour is discussed in terms of the influence of the unreacted austenite volume from the stage I austenitising reaction and the carbide product of the stage II austenitising reaction on the ductility. The present findings are predicted by the processing windows determined from the austempering kinetics.MST/3393