Abstract Studies have been conducted on the effect of overstressing in rotary bending fatigue on the fatigue properties of an annealed and austempered ductile iron containing 1.5 Ni–0.3 Mo. For various R ratios S–N curves were determined and the fatigue limit estimated. It was found that the fatigue limit was a function of the level of overstressing and cycle ratio. In the case of austempered samples a beneficial effect of overstressing was observed at a certain level of overstressing. This was related to the work hardening behaviour of the austenite phase. In annealed samples, a reduction in the fatigue limit was observed at all levels of overstressing. Copyright © 1995, Wiley Blackwell. All rights reserved
(EFFECT OF OVERSTRESSING ON FATIGUE BEHAVIOUR OF AUSTEMPERED DUCTILE IRON) Prasad Rao, P.; Padmaprabha
1995
Rotating bending fatigue tests were carried out on austempered ductile iron containing 1.5 wt% nickel and 0.3 wt% molybdenum. The ductile iron was austenitized at 900 or 1050 °C and then austempered at 280 or 400 °C for different lengths of time to obtain different microstructures. The fatigue strength was correlated with the amount of retained austenite and its carbon content, which were both determined by X-ray diffraction technique. While the tensile strength decreased with increasing retained austenite content, the fatigue strength was found to increase. Carbide precipitation was found to be detrimental to fatigue strength. Lower austenitizing temperature resulted in better fatigue strength. © 1994 Chapman & Hall.
(Kluwer Academic Publishers, Effect of microstructure on the fatigue strength of an austempered ductile iron) Shanmugam, P.; Prasad Rao, P.; Rajendra Udupa, K.; Venkataraman, N.
1994

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