The Effects of Residual Stress and Fretting Bridge Geometry on the Fretting Fatigue

摘要

Surface residual stresses in Ti-6Al-4V formed by shot peening, carbon or nitrogen ion implantation, and various combinations thereof, are compared with fretting fatigue life measurements on test coupons. In general, fretting fatigue life increases with an increase in residual compressive stress level. However, the results of the investigation suggest that other factors, such as surface hardness and the presence of brittle phases in surface layers, may also play an important role. It is found that nitrogen ion implantation decreases the surface residual compressive stress level of as-machined and shot peened test pieces, while carbon ion implantation has no significant effect. The effect of fretting bridge geometry — square-edge or round-edge bridges — is also reported.