Effect of Titanium Carbonitride Addition on Mechanical and Tribological Behaviors of TiCN-M2 High-Speed Steel Matrix Composites

The present work deals with the synthesis and characterization of TiCN-M2 high-speed steel matrix composites (TiCN-M2 HSS MMCs). TiCN with 0, 2, 5, 8 and 10 (wt.%) were dispersed in the matrices by mechanical alloying and sintered at different temperatures in a vacuum atmosphere. The density, phase analysis, microstructure characterization and mechanical properties were investigated. The experimental results showed that the predominant phases in the composites were alpha-Fe and various types of carbides, e.g., M6C, MC and M2C. With increased TiCN content, the hardness and wear resistance were initially enhanced but subsequently decreased. Meanwhile, the presence of coarsely distributed carbides and agglomerated TiCN disrupts the matrix's coherence; the bending strength and impact toughness showed a consistent decrease, and the impact fracture morphology exhibited brittle fracture and transgranular fracture. The friction coefficient displayed an increasing trend, and the wear rate showed an initial decrease followed by an increase. The primary wear mechanisms identified were abrasive wear and contact fatigue wear. With 2 wt.% TiCN, composites obtained peak overall performance, with hardness, bending strength and impact toughness measuring 712 HV, 1117 MPa and 5.5 J/cm2, respectively, yielding the highest wear resistance.