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<p>Cobalt-based composite coatings with varying TiC content (0 ~ 30 wt.%) were fabricated on M2 high-speed steel (HSS) substrates via laser cladding. Microstructural evolution, phase composition, microhardness, and tribological behavior were systematically characterized. Results indicate that TiC addition alters the phase constitution of the coating. With increasing TiC content, the relative contribution of the γ-Co phase decreases, while <i>β</i>-Co-related phases and Ti-containing carbides become increasingly prominent. Concurrently, Ti-related complex carbides formed through metallurgical reactions between TiC and alloying elements from the substrate. The microstructure evolved from relatively coarse dendritic regions to a more refined and heterogeneous morphology with increasing TiC content. Grain refinement was significantly enhanced after TiC addition, and the average grain size decreased from 21.19 to 12.10&#xa0;<i>μ</i>m at 20 wt.% TiC. The coating microhardness increases linearly with TiC content, peaking at 695.69&#xa0;HV<sub>0.3</sub> (36.6% higher than TiC-free coating) at 30 wt.% TiC addition, attributed to dispersion strengthening by unmelted TiC particles and in situ precipitated secondary carbides. Optimal wear resistance is achieved at 20 wt.% TiC addition, exhibiting a 57.1% reduction in volume wear rate due to enhanced microstructural homogeneity. However, higher-TiC content (30 wt.%) induces brittle spalling and increases friction coefficients from ceramic phase inhomogeneity. This study confirms that 20 wt.% TiC optimally balances hardness, wear resistance, and structural integrity for HSS tool applications.</p>

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Effect of TiC on Microstructure and Properties of Laser-Cladded Cobalt-Based Ceramic Coatings on High-Speed Steel

  • 期刊论文

  • 发表日期：

    2026年7月28日

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  • Zhenze Xia,
  • Shouqian Gong,
  • Xianhua Tian,
  • Qingbo Zhou,
  • Qingqing Wang

摘要

Cobalt-based composite coatings with varying TiC content (0 ~ 30 wt.%) were fabricated on M2 high-speed steel (HSS) substrates via laser cladding. Microstructural evolution, phase composition, microhardness, and tribological behavior were systematically characterized. Results indicate that TiC addition alters the phase constitution of the coating. With increasing TiC content, the relative contribution of the γ-Co phase decreases, while β-Co-related phases and Ti-containing carbides become increasingly prominent. Concurrently, Ti-related complex carbides formed through metallurgical reactions between TiC and alloying elements from the substrate. The microstructure evolved from relatively coarse dendritic regions to a more refined and heterogeneous morphology with increasing TiC content. Grain refinement was significantly enhanced after TiC addition, and the average grain size decreased from 21.19 to 12.10 μm at 20 wt.% TiC. The coating microhardness increases linearly with TiC content, peaking at 695.69 HV0.3 (36.6% higher than TiC-free coating) at 30 wt.% TiC addition, attributed to dispersion strengthening by unmelted TiC particles and in situ precipitated secondary carbides. Optimal wear resistance is achieved at 20 wt.% TiC addition, exhibiting a 57.1% reduction in volume wear rate due to enhanced microstructural homogeneity. However, higher-TiC content (30 wt.%) induces brittle spalling and increases friction coefficients from ceramic phase inhomogeneity. This study confirms that 20 wt.% TiC optimally balances hardness, wear resistance, and structural integrity for HSS tool applications.