Effect of Austempering Temperature on High Cycle Fatigue Behavior of an Austempered Ductile Iron (ADI)
Ductile irons with chemical compositions of Fe-3.6%C-2.6%Si-0.50%Cu-0.51%Ni were cast into standard keel blocks. Austenitizing heat treatment was carried out on test pieces at 875°C followed by austempering at 320, 365 and 400°C for times within the austempering processing window in a salt bath furnace. Rotating bending fatigue tests were performed with Roell Amsler UBM 200™ equipment at 3500 rpm at room temperature. Metallography and X-ray diffraction techniques were used to evaluate the fatigue life. Results indicate an increase of 10, 20 and 24% in fatigue life for specimens austempered at temperatures of 320, 365 and 400°C respectively, compared to that of as cast samples. According to the XRD test results; there is an increase in volume fraction of high carbon austenite by increasing the austempering temperature.
Adel Nofal and Mohamed Waly
S. Yazdani et al., "Effect of Austempering Temperature on High Cycle Fatigue Behavior of an Austempered Ductile Iron (ADI)", Key Engineering Materials, Vol. 457, pp. 493-498, 2011