Browsing by Author "Obiukwu, O. O."

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    The effect of surface finish on the low cycle fatigue of medium carbon steel
    (Federal University of Technology, Owerri, 2024-10) Obiukwu, O. O.; Nwafor, O. M. I.; Okafor, B.; Osueke, G.
    As fatigue cracks initiate predominantly at the free surface of a material, the condition of the surface can be assumed to be critical with regards to fatigue strength. The features of a mechanically prepared surface which are considered to be major factors affecting fatigue strength fatigue are stress concentration (a shape factor), dimension (a scale factor), and surface finish (a technological factor). This paper investigates the effect of surface finish on the fatigue life of AISI/ SAE 1040 (medium carbon steels). A compositional analysis was performed to ascertain the percentage of carbon in the materials. The specimens were machined to a precise gauge length and diameter and exposed to various surface finishes mainly; polishing and grinding machining surface conditions. A fatigue test was performed with the use of Avery Dennison and bending stress was obtained using the curve supplied with the machine. The results from the machine were converted to Mega Pascal (MPa) and the values used to plot S-N curves. The fatigue resistance for the specimens at various surface finishes of the different carbon steels was thus established. The results show that the polished surface with surface roughness (Ra = 0.20microns) has the longest fatigue life.