Abstract:
In this study, the effects of different annealing temperatures (200, 250, 300 and 350 ℃) on the microstructure, mechanical properties and friction and wear properties of TU2 oxygen-free copper were analyzed using OM, SEM/EDS, 3D/CLM, tensile testing machine, and friction and wear testing machine. The results show that with an increase in annealing temperature, the grain sizes of copper alloy gradually increased, and the number of annealing twins increased; the wear resistance exhibited a trend of increasing first and then decreasing. TU2 oxygen-free copper exhibited the highest yield strength (295.3 MPa), tensile strength (303 MPa), and the Vickers hardness (94.7 HV) at an annealing temperature of 200 ℃, demonstrating a superior balance between strength and plasticity. This was primarily attributed to the inhibition of dislocation movement by fine-grain strengthening, dislocation strengthening, and the presence of annealing twin boundaries. Regarding wear resistance, the sample annealed at 250 ℃ exhibited the best wear resistance, with a wear volume of only 30.73×10
-3 mm
3/(N·m), attributed to the retention of an appropriately work-hardened microstructure. Although a stable oxide film formed on the surface of the sample annealed at 350 ℃ (reducing the coefficient of friction to 0.414), its wear volume increased significantly compared to the 250 ℃ annealed sample. This degradation in performance was mainly due to the insufficient load-bearing capacity of the matrix, which weakened its resistance to ploughing and plastic deformation.