High cycle fatigue fracture and microstructure of TC11 titanium alloy at room temperature.
The microstructure of TC11 titanium alloy was observed and analyzed by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM).The results show that the fatigue fracture of TC11 titanium alloy under different loads is composed of three parts: fatigue source area, crack growth area and transient fracture area, and there are a large number of secondary cracks in the crack growth area perpendicular to the fatigue crack growth direction.With the increase of load, the number of secondary cracks increased, and the width of fatigue striations increased from 0. 6 m(475 MPa) to 1. 0 m(525 MPa).Under the action of alternating load, a large number of dislocation substructures were generated in the titanium alloy, and the dislocation was mostly accumulated at the/phase boundary, resulting in stress concentration, resulting in interface cracking and crack source formation, thus reducing the fatigue life.
The effect of solution temperature and cooling rate on microstructure and brinell hardness of TC11 titanium alloy rings was analyzed.The results showed that the volume fraction of the primary phase was mainly determined by the solid solution temperature. The content of the primary phase did not change significantly with the increase of the temperature within the range of the lower solid solution temperature. When the solid solution temperature was close to the phase transition point, the content of the primary phase decreased rapidly.The cooling rate had a significant effect on the morphology of the secondary phase.The hardness of the alloy increases with the increase of solution temperature and cooling speed.