Experimental and theoretical investigations of short fatigue crack growth in laser hardened medium carbon steel

摘要

Short fatigue crack growth has been studied on the surfaces of a normalised medium-carbon steel in the non-laser treated, partially laser treated and fully laser treated conditions. Tests were conducted at room temperature, on specimens subjected to reversed cyclic torsion at a frequency of 5 Hz. Experimental and predicted lives are well compared over a decade range in lifetime using a theory based on LEFM and invoking the stochastic nature of the fatigue process. Finally, transmission electron microscopy is used to record differences in short fatigue crack locations and crack paths on the differently treated specimen surfaces.