Influence of molybdenum on austempering behaviour of ductile iron - Part 4- Austempering behaviour of ductile iron containing 0.45%Mo

Austempering kinetic measurements and mechanical property measurements are presented for a ductile iron of composition Fe-3.56C-2.77Si-0.25Mn-0.45Mo-0 .43Cu-0.04Mg (wt-%) after austempering at 870 degrees C and austempering at 400, 375, 320, and 285 degrees C. The austempering kinetic measurements sh ow that increasing the Mo content of the iron, for example, to increase har denability, does not delay the austempering reaction significantly and the processing window is open for all the austempering temperatures studied. Th e mechanical properties determined for austempering temperatures of 400 and 375 degrees C show that the higher ductility grades of the austempered duc tile iron standards carl be satisfied as predicted by the open processing w indows. The ductility of the 0.45%Mo austempered iron is reduced compared w ith that measured in 0.13%Mo and 0.25%Mo irons austempered under the same c onditions. This is attributed to an increased amount and continuity of inte rcellular carbide as the Mo content increases. MST/4120.