CLADDING TECHNOLOGY SHANXI CO., LTDTiC-VC Based Anti-Abrasive Wear Cladding Electrode
Literature Overview
This 2004 publication in Mechanical Engineering Materials (机械工程材料) by researchers from the Welding Institute of Shanghai Jiao Tong University and the School of Materials Science and Engineering at Shandong University presents the development and characterization of a surfacing electrode reinforced with composite carbides (TiC-VC). The work addresses the critical need for improved abrasive wear resistance in mining, cement, and power industry equipment subjected to severe sliding and impact wear conditions.
Core Technical Points
Design Philosophy of Composite Carbide Reinforcement
The electrode design incorporates a dual-carbide system where TiC provides high hardness (HRC 85–90) and thermal stability, while VC contributes excellent hot hardness and thermal shock resistance. The complementary nature of these two carbides creates a synergistic effect:
- TiC: High melting point (3140°C), excellent chemical stability, and resistance to oxidation at elevated temperatures.
- VC: Superior thermal shock resistance, high red hardness, and effective resistance to adhesive wear.
- Composite effect: The mixed carbide system prevents preferential dissolution of a single carbide type, maintaining a more uniform microstructure during service.
Microstructure and Hardness Distribution
| Region | Phase Composition | Hardness (HRC) | Notes |
|---|---|---|---|
| Surface layer | Primary TiC + VC + martensite matrix | 58–65 | Highest wear resistance |
| Transition zone | Dissolved carbides + retained austenite | 45–55 | Gradient in hardness |
| Interface/HAZ | Softened ferrite + pearlite | 30–40 | Dilution zone |
| Substrate | Original structure | 25–35 | Base material |
The microstructure exhibits a cellular dendritic pattern with carbide particles distributed at dendrite boundaries and within the intercellular regions. The matrix is predominantly martensitic with some retained austenite, providing toughness to prevent catastrophic spalling.
Wear Test Results
Abrasive wear tests conducted against alumina (Al₂O₃) and silica (SiO₂) wear media demonstrate:
- 3–5 times the wear life compared to conventional high-carbon martensitic electrodes (e.g., D266).
- Improved performance in wet and abrasive slurry environments due to the corrosion-resistant carbide network.
- Minimum wear rate achieved at a TiC:VC ratio of approximately 60:40 to 70:30 by weight.
Process Considerations for Electrode Surfacing
| Parameter | Recommended Value | Rationale |
|---|---|---|
| Electrode diameter | φ3.2–φ4.0 mm | Adequate for most field applications |
| Welding current | 80–120 A (DCEN) | Ensures full penetration without excessive dilution |
| Travel speed | 80–150 mm/min | Balances deposition rate and dilution |
| Number of passes | 2–3 | First pass for bonding, subsequent for wear layer |
| Preheating | 150–250°C | Reduces HAZ hardness and prevents cracking |
| Post-weld cooling | Air cool or controlled rate | Avoids rapid quenching that may cause cracking |
Engineering Practice and Defect Analysis
Common defects encountered during field application of TiC-VC composite carbide electrodes include:
- Cracking: Caused by excessive carbon equivalent in the dilution zone. Countermeasure: use low-carbon filler for the first (bonding) pass.
- Porosity: Resulting from moisture in electrode coating or inadequate shielding. Countermeasure: bake electrodes at 350–400°C for 2 hours before use.
- Insufficient fusion: Due to low current or excessive travel speed. Countermeasure: increase current by 10–15% or reduce travel speed.
- Carbide agglomeration: Uneven carbide distribution leading to local soft spots. Countermeasure: ensure proper electrode storage and use within recommended shelf life.
Key Reflections
The TiC-VC composite carbide approach represents a sophisticated materials design strategy that leverages the complementary properties of two different carbide systems. From a practical standpoint, the success of this electrode design depends heavily on proper application technique — the inherent benefits of the composite carbide system cannot be realized if the deposition process introduces excessive dilution or defects. Engineers should pay particular attention to the first-pass bonding layer, which serves as a metallurgical bridge between the substrate and the high-carbon wear layer. The selection of appropriate shielding (flux coating design) and welding parameters is critical for achieving the designed microstructure and wear performance.