FIGURE 2 Surface topography of specimen (Measuring dimensions: 0.353×0.265mm):
Loading frequency shows no effect on fatigue life of TC17 at R = -1, 0.1, 0.5 and 0.7.28 Therefore, USF-2000 ultrasonic tensile fatigue test system with a load ratio of R = -1is used because of its high efficiency and low energy consumption.29 A cooling system is adopted to keep the testing environment at room temperature (20) to avoid the material behavior affected by the internal heat generation. The minimum stress amplitude is 600 MPa, increasing interval is 15 MPa in this experiment. Characteristic of the fatigue fracture morphology was observed by SEM.
TABLE 1 Data of width and depth (μm)