TiC-VC Based Abrasion-Resistant Overlay Electrode: Composition Design and Performance Evaluation

Literature Overview

The study by Yang Shanglei, Lv Xueqin, Zou Zengda, and Lou Songnian (2004), published in Materials in Mechanical Engineering (Vol. 28, No. 6, pp. 20-22), presents a systematic investigation into the development of a novel abrasion-resistant overlay welding electrode utilizing TiC-VC carbide reinforcement. Conducted at the Welding Institute of Shanghai Jiao Tong University and the School of Materials Science and Engineering of Shandong University, this work addresses the critical challenge of balancing hardness, crack resistance, and weldability in hardfacing consumables. The authors employed iron titanate, iron vanadate, graphite, and synthetic rutile as flux components, leveraging high-temperature arc metallurgical reactions to in-situ generate TiC and VC carbides within the weld metal. This approach eliminates the need for externally added hard carbide particles, which often cause porosity and poor fusion in conventional hardfacing electrodes.

Core Technical Findings

The experimental design focused on systematically varying the proportions of iron titanate (FeTi), iron vanadate (FeV), and graphite in the electrode coating composition. The resulting overlay layers were characterized using scanning electron microscopy (SEM), welding process performance tests, and abrasive wear testing. The key findings can be summarized as follows:

The microstructural analysis revealed that the overlay weld metal consists of a low-carbon martensitic matrix with fine, uniformly distributed TiC and VC carbide particles. These carbides act as effective wear-resistant phases, providing both mechanical reinforcement through dispersion strengthening and microstructural stability under abrasive loading. The low carbon content in the martensite matrix is crucial, as it limits the formation of brittle cementite (Fe3C) networks while maintaining adequate toughness to resist cracking during cooling and service.

Process Performance and Metallurgical Analysis

The trade-off between hardness and weldability represents the central engineering challenge in hardfacing consumable design. As the proportion of carbide-forming elements increases, the weld pool becomes more refractory, leading to increased spatter, poor slag fluidity, and reduced penetration. The authors found that the synthetic rutile flux component plays a critical role in stabilizing the arc and promoting slag detachment, which partially mitigates the process degradation caused by higher carbide content. The in-situ carbide formation mechanism involves the reduction of titanium and vanadium oxides by carbon in the arc zone, followed by precipitation of TiC and VC during solidification.

The crack resistance performance of the developed electrode exceeded that of both D618 and D667, which are widely used hardfacing electrodes in industrial applications. This superior crack resistance can be attributed to the lower carbon content in the matrix, which reduces the driving force for brittle phase formation, and the uniform distribution of TiC and VC particles, which do not create the severe stress concentrations associated with large externally added carbide particles.

Engineering Practice Implications

For engineers working in the field of hardfacing applications, this study provides valuable guidance on the selection and design of abrasion-resistant overlay consumables. The TiC-VC approach is particularly suitable for applications involving high-velocity solid particle erosion, such as pneumatic conveying systems, sand and gravel handling equipment, and mineral processing components. The 8-fold improvement in wear resistance over D667 represents a significant economic advantage, as it extends component service life and reduces maintenance frequency. However, the degradation in welding process performance requires careful consideration during production, including the use of appropriate preheating temperatures, controlled deposition rates, and potentially multi-pass welding strategies to manage thermal input and residual stresses.

Study Insights and Reflections

The in-situ generation of carbide phases through arc metallurgy represents an elegant solution to the porosity and fusion problems associated with externally added hard particles. This approach is particularly relevant for field repair applications where consumable flexibility and ease of use are paramount. The study also highlights the importance of systematic composition optimization, as the optimal balance between wear resistance and weldability requires careful experimentation rather than simple component addition. Future work could explore the effects of post-weld heat treatment on the microstructure and residual stress state of TiC-VC overlays, as well as the long-term wear behavior under cyclic loading conditions.