Research on the chip formation mechanism of orthogonal cutting in particulate reinforced titanium matrix composites

Particle-reinforced titanium matrix composites (PTMCs) have recently become popular in the field of metal matrix composite research because of their outstanding mechanical properties. However, the diffuse distribution of strong reinforcing phases within a material influences chip formation, resulting in tool wear and lower cutting performance during machining. Examining the chip formation mechanism in PTMCs is crucial for enhancing machining performance. This paper explored how particles affect the chip formation process during the orthogonal cutting of PTMCs by utilizing both experimental and numerical methods for analysis. After characterizing the microstructure of PTMCs via image recognition technology, a finite element cutting model was established. Based on the dislocation theory, the effects of reinforcing phase damage and reinforcing phase content on the chip formation of PTMCs were analyzed. The results suggested that the chips exhibited a serrated shape with brittle cracks sprouting and expanding from the free surface. With a higher content of the reinforcing phase, the chip morphology of the PTMCs increases in terms of the degree of serration, and the chip formation process is influenced more by the particles. Furthermore, the chip formation results from a combination of thermoplastic shear instability, periodic fracture, and particle damage. As the cutting speed gradually increases, the PTMCs are more affected by the thermal softening effects, and the main cutting force generated during cutting gradually decreases from 625 to 589 N. Both the values and trends of the experimental results can verify the accuracy of the simulation.