LOW CYCLE FATIGUE ENHANCEMENT BY ION IMPLANTATION

ION IMPLANTATION IS AN EFFECTIVE PROCESS TO CREATE COMPRESSIVE STRESS IN THE SUBSURFACE REGIONS OF METALLIC COMPONENTS AND THEREBY ENHANCE THEIR RESISTANCE TO FATIGUE INITIATED FAILURES. ION IMPLANTATION OF LIGHT INTERSTITIAL IONS (SUCH AS BORON, CARBON OR NITROGEN) INTO TITANIUM-BASED ALLOYS (OR FERROUS ALLOYS) IS A MICROSCOPIC SHOT PEENING PROCESS THAT CREATES TREMENDOUS COMPRESSIVE STRESS ON THE SURFACE OF TREATED COMPONENTS. THE COMPRESSIVE STRESS IS THE UNDERLYING REASON FOR THE SLOWDOWN IN THE CRACK INITIATION PHASE AND CRACK PROPAGATION MODE. IN ADDITION THE PROCESS HAS BEEN SHOWN TO BE VERY EFFECTIVE TO MINIMIZE GALLING (ESPECIALLY IN TITANIUM BASED ALLOYS) AND NOTCH CREATION IN HANDLING OF TITANIUM ALLOYS THAT CAN GIVE RISE TO FATIGUE FAILURE.