Enhancing Fatigue Life through Ultrasonic Nanocrystal Surface Modification
Advancements in surface treatments have provided the opportunity to utilize alloys at higher stresses during fatigue loading. Ultrasonic Nanocrystal Surface Modification (UNSM) as patented by Sun-Moon University in South Korea provides shot peening at a frequency of 40 kHz, greatly increasing the shots per square mm. A gearing alloy, 9310 steel, was experimentally studied with four surface treatments: case carburizing, induction heat-treating, case carburizing and traditional shot peening and case carburizing and UNSM. Fatigue experiments, SEM analysis, white light interferometry and Vickers hardness testing were performed in order to compare the material characteristics after each treatment. UNSM raised the endurance limit 15.5% more than the traditional shot peening.