Abstract
An investigation was carried out to examine the influence of notch sensitivity on fatigue behaviour of austempered ductile iron (ADI). Samples were made of ductile iron with a chemical composition of 3.55% C, 2.18% Si, 0.35% Mn, 0.022 P, 0.008 S and 0.045% Mg. The samples were heat treated by austenitizing at 900℃ for 1 h and then rapidly quenched into two different salt baths at 350 and 400℃ for 1 h each. This work aims at studying the capability of mechanical stress analysis software (ANSYS 12.0), as a nondestructive tool, to characterize and quantify the fatigue strength of the notched ADI samples with different radii (from 1 to 3 mm). In addition, experimental testing was performed using rotary bending fatigue machine on notched samples with radii of 1, 1.5 and 2-mm to verify the theoretical data obtained by ANSYS-12. The results show that the predicted fatigue strength estimated by ANSYS-12 is very close to the experimental one. Therefore, fatigue performance of the rotating parts made of ADI can be estimated theoreticcally using ANSYS 12.0. The fatigue strength of these parts can also be improved by increasing the formed filled radius due to decreasing the notch sensitivity factor.
Highlights
An investigation was carried out to examine the influence of notch sensitivity on fatigue behaviour of austempered ductile iron (ADI)
Experimental testing was performed using rotary bending fatigue machine on notched samples with radii of 1, 1.5 and 2-mm to verify the theoretical data obtained by ANSYS-12
The results show that the predicted fatigue strength estimated by ANSYS-12 is very close to the experimental one
Summary
Austempered ductile iron (ADI) is widely used in Industry because it offers a combination of low cost, design flexibility, high strength-to-weight ratio, good toughness, wear resistance, and fatigue strength [1,2,3]. ADI alloys possess mechanical properties that are superior to conventional ductile iron and comparable to heat treated forged steels [4,5]. These attractive properties of ADI are related to its unique microstructure that consists of ferrite and high carbon austenite which is often referred to as ausferrite [6]. Reduction in fatigue limits due to notch effect will be firstly determined analytically using mechanical stress analysis software (ANSYS 12.0) and verified by conducting experimental tests on a rotary bending fatigue machine
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