Zhuojin Pipe Fitting Co., LtdTitanium Carbide Ceramic Particle Reinforced Iron-Based Overlay Alloy Layer Microstructure and Wear Resistance
Literature Overview
This paper by Zhu Shuzhi, Jia Hua, Xu Ling, and Yu Jinghang from Dalian Ocean University, published in Ordnance Materials and Engineering (Volume 49, Issue 4, 2026, pages 74-79), investigates the microstructural evolution and tribological performance of iron-based overlay alloy layers reinforced with in-situ synthesized titanium-containing ceramic particles. The research was supported by the 2025 Dalian Ocean University Provincial Student Innovation and Entrepreneurship Training Program, Liaoning Provincial Science and Technology Joint Program, and Liaoning Provincial Department of Education Basic Science Research Project. The study is highly relevant to engineers designing overlay weld cladding for wear-critical components in marine, mining, and material handling applications.
Core Technical Content
The study compares two overlay alloy compositions deposited on Q235 steel substrates by open-arc surfacing (明弧堆焊): a base Fe-Cr-C-B-N composition and a Ti-modified Fe-Cr-C-B-N-Ti composition with 4 mass% titanium addition. The characterization employed metallographic microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), Rockwell hardness testing, and pin-on-disc wear testing.
Microstructural Composition Comparison
| Feature | Fe-Cr-C-B-N (Base) | Fe-Cr-C-B-N-Ti (4% Ti) |
|---|---|---|
| Matrix phase | Lath martensite (M), residual austenite (A) | Lath martensite (M), residual austenite (A) |
| Primary carbides | M₂₃(C,B)₆, M₃(C,B), M₂B | M₂₃(C,B)₆, M₃(C,B), M₂B (reduced quantity) |
| Titanium phases | None | TiC, TiB₂, TiN |
| Eutectic distribution | Continuous network | Interrupted network, more uniform |
| Austenite grain size | Coarser | Refined with internal lath martensite |
| Hardness | 62.7 HRC (calculated) | 66 HRC |
| Wear volume loss | 0.0542 g | 0.0429 g |
| Improvement | Reference | +5.3% hardness, -20.8% wear |
Mechanism of Ti Addition Effect
The addition of 4% titanium produces a multi-mechanism improvement in wear resistance:
- In-situ ceramic particle formation: Ti reacts with C, B, and N during solidification to form TiC, TiB₂, and TiN. These phases are thermodynamically stable with extremely high hardness (TiC: ~2800 HV, TiB₂: ~4000 HV, TiN: ~1300 HV), providing effective resistance to abrasive wear.
- Grain refinement: The presence of titanium carbide particles acts as heterogeneous nucleation sites, refining the primary austenite grain structure. Smaller austenite grains transform to finer lath martensite, improving the overall toughness-hardness balance.
- Eutectic modification: The Ti addition reduces the quantity of M₂₃(C,B)₆, M₃(C,B), and M₂B phases in the eutectic network while improving their distribution uniformity. This prevents the formation of continuous brittle networks that could initiate microcracks under cyclic loading.
- Dispersion strengthening: The fine, irregularly shaped Ti-containing ceramic particles are uniformly dispersed throughout the matrix, creating a composite-like microstructure with enhanced load-bearing capacity.
Engineering Practice Considerations
For engineers specifying overlay weld cladding for wear applications, several practical considerations emerge from this study:
Process Parameter Recommendations
| Parameter | Recommended Range | Rationale |
|---|---|---|
| Ti addition level | 3-5 mass% | Below 3% insufficient ceramic formation; above 5% may cause excessive brittleness |
| Open-arc surfacing current | 200-350 A | Adequate heat input for dilution control and particle formation |
| Travel speed | 200-400 mm/min | Balances deposition rate with cooling rate for fine microstructure |
| Layer thickness | 3-5 mm per pass | Ensures adequate dilution control and uniform composition |
| Number of passes | 3-5 layers | Builds sufficient cladding thickness while maintaining microstructural quality |
Common Defects and Countermeasures
| Defect Type | Root Cause | Countermeasure |
|---|---|---|
| Surface porosity | Inadequate shielding gas coverage | Use of flux-cored wire or improved gas flow pattern |
| Cracking in overlay | Excessive carbon equivalent and rapid cooling | Preheat substrate to 150-200°C; control interpass temperature |
| Non-uniform Ti distribution | Incomplete mixing of Ti powder in wire | Ensure thorough powder blending before wire manufacturing |
| Excessive dilution | High heat input or thin first layer | Use lower current for first pass; increase travel speed |
Study Insights and Independent Reflection
The most significant engineering insight from this study is the demonstration that relatively modest titanium additions (4%) can produce disproportionately large improvements in wear resistance (20.8% reduction in wear loss). This suggests that the Ti-containing ceramic phases act as efficient wear-resistant reinforcements even at relatively low volume fractions. The key is the in-situ formation mechanism—TiC, TiB₂, and TiN form during solidification rather than being added as pre-formed particles, which ensures better bonding to the matrix and eliminates interface-related failure modes.
I note that the open-arc surfacing method used in this study is a practical, cost-effective process suitable for field application. Unlike submerged arc surfacing or plasma transfer arc surfacing, open-arc surfacing requires minimal equipment and can be performed in various orientations. However, the trade-off is reduced shielding effectiveness, which may lead to surface oxidation and porosity. For critical applications, I would recommend supplementing with post-weld grinding or a thin finishing layer to ensure a defect-free surface.
The wear testing methodology (pin-on-disc) provides useful comparative data but should be interpreted cautiously for real-world applications. Actual wear conditions in mining or marine environments involve multi-body abrasion, impact, and corrosion-abrasion synergy that cannot be fully replicated in laboratory tests. Engineers should use this data as a relative ranking tool rather than absolute performance prediction.
Concluding Summary
This study demonstrates a practical approach to enhancing the wear resistance of iron-based overlay weld cladding through in-situ titanium ceramic particle formation. The 4% Ti addition strategy produces a refined, multi-phase microstructure with significantly improved tribological performance while maintaining the process simplicity of open-arc surfacing. For engineers specifying wear-resistant overlay cladding on carbon steel components, this composition represents a viable option that balances performance, cost, and manufacturability. The key to successful implementation lies in controlling dilution, ensuring uniform Ti distribution, and managing residual stresses through appropriate post-weld treatment.