The effect of roughness and residual stresses on fatigue life time of an alloy of titanium

The quality of titanium alloy parts in the aeronautical field demands great reliability, especially in fatigue resistance. This is mainly determined by surface integrity, which is in turn defined by geometrical, mechanical and metallurgical parameters. The present article provides a study of the influence that surface integrity has on the fatigue life of Ti6Al4V. Milling plans of procedure generating widely varying surface integrities were performed on fatigue test coupons. Four-point bending tests were then conducted. No influence of the geometric and metallurgical parameters was observed. Only the mechanical parameter seems to have a preponderant influence on fatigue life.