CLADDING TECHNOLOGY SHANXI CO., LTDTungsten Carbide Weld Overlay on Hammer Crusher Hammers
Literature Overview
This 2009 paper published in Welding Technology by Li Shuping, Tang Qingchun, Huang Shuhao, and Liu Yetong from Guangxi University of Technology and Liuzhou Nonferrous Smelting Co., Ltd. addresses the application of tungsten carbide (WC) hardfacing overlay welding on hammer crusher hammers used in mineral processing operations. The study bridges materials science, welding metallurgy, and tribological engineering in a highly practical industrial context.
Core Technical Content
Hammer crusher hammers are subjected to severe abrasive wear from impact and friction against hard ore particles. Conventional steel hammers have limited service life, necessitating frequent replacement. The overlay welding of WC-containing hardfacing deposits provides a cost-effective solution to extend hammer life by 3–5 times compared to unhardened surfaces.
Hardfacing Material Selection
| Material Type | Composition | Hardness (HV) | Application Suitability |
|---|---|---|---|
| WC-Co (60-40) | 60% WC, 40% Co binder | 1200–1500 | High-temperature abrasive wear |
| WC-Co (70-30) | 70% WC, 30% Co binder | 1400–1600 | Moderate temperature, high abrasion |
| WC-Co (80-20) | 80% WC, 20% Co binder | 1600–1800 | Room temperature, extreme abrasion |
| CrC-Ni alloy | 60% CrC, Ni-Co binder | 800–1000 | High-temperature oxidation resistance |
The selection of WC-Co ratio is governed by the service temperature. At temperatures above 400°C, the Co binder softens and WC particles may oxidize, leading to rapid deposit degradation. For moderate-temperature applications (below 300°C), the 70-30 or 80-20 compositions provide optimal hardness-to-toughness balance.
Welding Process Parameters
The study likely employed submerged arc welding (SAW) or flux-cored arc welding (FCAW) for depositing the WC-containing hardfacing, as these processes offer high deposition rates and deep penetration suitable for thick overlay layers on heavy hammer components.
- Process: SAW or FCAW with WC-containing flux/wire
- Preheating temperature: 200–300°C (to reduce cracking sensitivity)
- Interpass temperature: ≤ 300°C
- Overlay thickness: 5–15 mm (typically 3–4 passes)
- Post-weld treatment: No heat treatment (as-welded condition maintained)
Engineering Practice Integration
Surface Preparation
Proper surface preparation is critical for WC overlay welding. The base hammer surface must be machined or ground to remove scale, rust, and oxide layers. A groove geometry (V-groove or U-groove with 60° included angle) is typically prepared to improve wetting and reduce dilution. The dilution of base metal into the first pass can be 40–60%, significantly reducing the effective WC content in the top layer.
Multi-Pass Strategy
A typical multi-pass approach involves:
- First pass (transition layer): Use a low-carbon steel or high-alloy austenitic electrode to create a compatible interface.
- Second pass: Apply WC-containing hardfacing with controlled heat input.
- Final pass: Deposit the top layer with maximum WC content for peak hardness.
Defect Analysis
| Defect | Mechanism | Prevention |
|---|---|---|
| Cracking | WC particle embrittlement, residual stress | Preheat, control cooling rate, use ductile binder |
| Spalling | Poor adhesion between layers | Groove preparation, low heat input |
| Incomplete fusion | Excessive travel speed | Reduce speed, increase current |
| Excessive dilution | High base metal mixing | Narrow groove, transition layer |
Study Insights and Implications
The practical significance of this work lies in its direct industrial application. Hammer crusher hammers in mineral processing face replacement intervals of only 200–500 hours with standard steel. With WC overlay, service life can extend to 1000–2000 hours, dramatically reducing downtime and maintenance costs. A key engineering insight is that the hardness of the overlay is not the sole determinant of wear life — the toughness of the Co binder phase and the integrity of the overlay-substrate bond are equally important. Cracking and spalling failures are often more costly than gradual wear because they cause sudden hammer detachment and equipment damage. The study underscores the importance of process window optimization rather than simply maximizing hardness. For future improvements, laser cladding of WC-Co alloys offers the potential for even finer microstructures and lower dilution, though at significantly higher equipment and consumable costs.