Fatigue Behavior and Fracture Features of Ti-15Mo Alloy in β-, (α + β)-, and Ultrafine-Grained Two-Phase States

The influence of the ultrafine-grained structure formed by equal-channel angular pressing via “Conform” scheme on fatigue behavior metastable β-alloy Ti-15Mo has been studied. It is shown that alloy with a two-phase achieved best mechanical properties and enhanced endurance limit (up to 710 MPa basis 107 cycles) due total contribution grain boundary, dislocation, phase strengthening mechanisms. A fractographic analysis fracture surface samples after tests showed features crack propagation depending type microstructure. general distinctive failure in initial coarse-grained (α + β)-, single-phase β-, β)-states are revealed. In all samples, nucleated propagated downward, i.e., perpendicular direction applied pressures. surfaces had high roughness were characterized presence large number secondary cracks, as compared analogues.