## 3 Results and Discussion
### Tribological Behavior
Figure 12 shows the SEM images and energy spectra of the wear surfaces of CS_QAT and CS_IQAT at different frequencies. Furrows, flaking, oxidation, and adhesion were observed on the wear surfaces of CS_QAT and CS_IQAT, indicating that abrasive and adhesive wear occurred. In addition, the main wear mechanism of the CS_IQAT specimens changed from adhesive wear to abrasive wear with increasing frequency. The revelation of this mechanism is of great significance for the optimization of process parameters and improvement of part design. Overall, the wear surface of CS_IQAT specimens is flatter compared to CS_QAT specimens at the same frequency. This can be attributed to the finer and more uniform organization of Fe3 C in CS_IQAT, as well as the higher hardness and yield stress. The fine and uniform organization effectively prevents crack propagation; the high hardness helps reduce wear on the material surface and the high yield stress helps maintain the shape and integrity of the material surface. These factors work together to make CS_IQAT specimens exhibit greater wear resistance under the same operating conditions. When the frequency is 2 Hz, traces of flaking and plowing are observed on the surface of CS_QAT and CS_IQAT specimens, where the flaking phenomenon is more serious in CS_QAT. When the frequency is increased to 3 Hz, obvious traces of adhesion and furrowing can be observed on the wear surfaces of both, which leads to an increase in the roughness of the wear surfaces and an increase in the loss of material. The microstructures of both CS_QAT and CS_IQAT are composed of soft ferrite and hard Fe3C particles. During the wear process, the load application deforms the ferrite and part of the material is transferred to the friction surface or the surface of the corresponding GCr15 ball. At the same time, the hard Fe3C particles are exposed on the friction surface and act as abrasive particles. When the frequency is increased to 4 Hz, the relative sliding is further increased, generating a larger friction force, which leads to more frictional heat and increased adhesion. The energy spectrum results show that oxygen elements are present on the wear surfaces of both, indicating that some high-temperature oxidation reaction occurs during the adhesive wear process. The CS_QAT specimens have a higher oxygen content and more severe surface adhesion. Finally, when the frequency is increased to 5 Hz, the adhesion phenomenon of both is reduced, while the furrow phenomenon becomes obvious. This may be due to the fact that at high frequencies, the oxidation process is more intense and the generated oxide layer is able to partially alleviate the adhesive wear, thus reducing the adhesion phenomenon. However, the furrowing phenomenon becomes more significant due to the presence of oxide particles and exposed Fe3C particles. Figure 11: Three-dimensional morphology of CS_QAT and CS_IQAT wear at different frequencies: (a) CS_QAT; (b) CS_IQAT. Figure 12: SEM images and energy spectra of CS_QAT and CS_IQAT on the worn surface at different frequencies: (**a,b**) 2 Hz; (**c,d**) 3 Hz; (**e,f**) 4 Hz; (**g,h**) 5 Hz; (**E**) 4 Hz CS_QAT energy spectrum; (**F**) 4 Hz CS_IQAT energy spectrum.