Fatigue Crack Initiation In Surface Ground Ti-6a1-4v

Author:  Cammett, III, John
Source:  Metcut Research Assoc.
Doc ID:  1953001
Year of Publication:  1953
Abstract:  
An experimental study was conducted to determine the effects of surface grinding practice on fatigue of Ti-6A1-4V. Variations in fatigue strength as great as 5:1 were experienced as a result of changing grinding parameters over the range typically employed in industry. Extensive microstructural alteration and damage occurred at and near the specimen surfaces as a result of abusive grinding practices involving high metal removal rates. Examination of ground surfaces by optical microscopy, replica transmission electron microscopy, and scanning electron microscopy showed that abusive grinding produced extensive microcracking and smearing of specimen surfaces. Subsequent examination of specimens during the course of fatigue revealed that the low observed fatigue strength obtained with abusively ground surfaces resulted primarily from premature initiation and propagation of fatigue cracks from grinding microcracks.