A surface integrity model of TC17 titanium alloy by ultrasonic impact treatment

Ultrasonic impact treatment (UIT) is a mechanical surface treatment. In this study, a surface integrity empirical model of TC17 titanium alloy by UIT was established to study the processing effect of UIT. A surface roughness index function prediction model was established. The relationship between microhardness, residual stress, and depth h was characterized by an exponential function and a decaying cosine function, respectively, and the relationship between the control factor and the process factor was established. The parameters such as feed rate, spindle speed, extrusion depth, and number of impact per unit area were analyzed to evaluate the result of UIT. The minimum roughness after ultrasonic impact treatment is 0.3 μm, and when the feed rate is 0.04 mm, the spindle speed is 50 r/min, the extrusion depth is 0.01 mm, and the number of impacts per unit is about 10,000 times; the microhardness layer is about 120 μm; the residual compressive stress layer is about 200 μm, the microhardness value is as high as 670 HV; and the maximum residual compressive stress value is − 1250 MPa.