influence of deformation technology on fatigue properties of titanium

The influence of commercially pure Titanium microstructure on fatigue properties and their improvement or deterioration is analyzed in the presented contribution. One tested material was after cold drawing the other after severe plastic deformation by Equal Channel Angular Pressing (ECAP). Intense plastic deformation (ECAP) resulted in yield point 100 % higher and UTS 97% higher than obtained by traditional cold drawing. The ductility was 57% lower than for cold drawing. However, the fatigue properties namely the degradation of fatigue properties were influenced by sever plastic deformation in a way not consistent with the usually counted influence on mechanical properties and more, the fatigue limit was lower for high numbers of fatigue cycles. For N = 5,5. 10⁵ the fatigue limits in torsion τ_C for Ti after ECAP and after cold drawing were identical. For N < 5,5. 10⁵ cycles the τ_C for Ti after ECAP was higher, but for N > 5,5. 10⁵ cycles it was lower.