EFFECT OF NICKEL ON THE MICROSTRUCTURE, MECHANICAL AND TRIBOLOGICAL PROPERTIES OF AUSTEMPERED DUCTILE CAST IRON FOR STEERING KNUCKLE APPLICATIONS.

The research article address, the mechanical properties such as fatigue, impact strength and tribological properties of Austempered ductile iron (ADI) has been investigated. The samples of ADI iron were austenitized at 927°C for 2 hrs and later it was under austempering process for 2 hrs at a temperature range of 240°C to 400°C. Experiments under axial loading has been carried out on three different compositions (without Ni(X), 0.22 wt % Ni (X₁), 0.34 wt. % Ni (X₂). Fabricated test bars were converted in to as per ASTM standard samples for different tests. In order to study the influence of chunky nickel morphology studies on fatigue life and impact strength were carried out on a second set of specimens without any microstructural defect. Metallurgical analyses were performed on all the samples of heat treated samples (AF - Ausferrite, MB - Mixed bainite, M - Martensite, RA - Retained Austenite and N-Nodule) were found and compared. It was found that a mean content of 22% of chunky nickel in the microstructure (with respect to total Ni content) influence considerably the fatigue and impact strength properties of the cast iron. Moreover tribological properties of the specimens were also studied under dry sliding conditions at various sliding speed and load. The wear resistance and coefficient of friction were found to increase with increase in load and sliding speed. [ABSTRACT FROM AUTHOR]