Mo alloyed austempered ductile irons

Measurements of the austempering kinetics and mechanical properties of irons containing 3.5% C, 2.7% Si, 0.25% Cu, 0.25% Mn and Mo contents of 0.12%, 0.25% and 0.45% after austenitising at T-gamma = 870 degrees C and austempering at T-A = 285, 320, 375 and 400 degrees C are presented. They show the Mo does not delay the stage I and stage II austempering reactions significantly. Consequently the processing window remains open for all the irons and conditions studied and the mechanical properties satisfy the ASTM standard. This behaviour is shown to differ from that of Mn.