CLADDING TECHNOLOGY SHANXI CO., LTDCurrent Status and Development Trends of Roll Cladding
Literature Overview
Published in 2010 in the journal Electric Welder, this review article by Zhang Yingyue, Bao Yefeng, Jiang Yongfeng, and Yang Ke from Hohai University provides a comprehensive survey of the state of the art and emerging trends in roll cladding technology. Roll cladding is a critical manufacturing process in the steel, aluminum, mining, and paper industries, where cylindrical rolls require periodic resurfacing to restore dimensional accuracy and surface hardness after wear or damage. The paper examines conventional welding methods, advanced cladding techniques, and the evolving requirements driven by higher production speeds and more aggressive operating conditions.
Classification of Roll Cladding Methods
The authors categorize roll cladding techniques into several major groups, each with distinct process characteristics and applicability ranges:
| Method | Typical Hardness (HV) | Dilution Rate | Cycle Time | Key Limitation |
|---|---|---|---|---|
| Submerged Arc Welding (SAW) | 250–400 | 15–25% | Moderate | Requires extensive post-weld machining |
| Gas Metal Arc Welding (GMAW) | 300–500 | 20–35% | Fast | Higher dilution, limited alloy retention |
| Flux-Cored Arc Welding (FCAW) | 350–600 | 10–20% | Moderate | Flux handling complexity |
| Plasma Transferred Arc (PTA) | 600–1200 | 2–8% | Moderate | High equipment cost |
| Laser Cladding | 800–1500 | 1–5% | Fast per pass | Limited build-up thickness per pass |
| TIG Overlay | 400–700 | 5–15% | Slow | Low deposition rate |
Technical Challenges and Industry Trends
The review identifies several persistent challenges in roll cladding:
- Dilution control — maintaining alloy composition in the cladding layer is essential for achieving target hardness and wear resistance. High dilution rates in conventional arc welding methods can reduce the effective alloy content below the threshold needed for hard phase formation.
- Residual stress management — the large thermal gradients inherent in roll cladding generate significant residual stresses that can lead to distortion, cracking, or premature failure during grinding and service.
- Surface finish requirements — after cladding, rolls must be ground to tight surface roughness (typically Ra 0.2–0.8 μm) and dimensional tolerances (IT7 or better), which requires adequate material build-up and limits the achievable deposition rate.
The development trends discussed include:
- Transition to laser cladding and PTA — these methods offer superior dilution control and higher hard phase retention, making them increasingly attractive for high-performance roll applications such as hot-strip mill rolls and mining crushing rolls.
- Development of new cladding alloys — advanced Ni-based, Co-based, and Fe-Cr-C-B alloy systems are being developed to meet the demands of higher-temperature and more abrasive service conditions.
- Integration of preheating and post-weld heat treatment — controlled thermal cycling before and after cladding is becoming standard practice to minimize residual stresses and improve microstructural uniformity.
- Online monitoring and process optimization — the use of arc voltage/current monitoring, thermal imaging, and in-situ hardness measurement is emerging as a means to ensure consistent cladding quality.
Engineering Practice Considerations
For engineers responsible for roll refurbishment programs, several practical guidelines emerge from this review:
- Base material assessment — prior to cladding, the base roll steel must be evaluated for weldability, hydrogen cracking susceptibility, and residual stress state. Preheating temperatures of 200–400°C are typically required for medium and high carbon steels.
- Layer thickness planning — the total cladding thickness should account for both the required functional layer and the material to be removed during post-weld grinding. A typical allowance of 1–3 mm per pass for grinding stock is necessary.
- Crack prevention — the use of low-hydrogen electrodes or consumables, controlled interpass temperatures, and post-weld stress relief treatments are essential for preventing both hot cracking and cold cracking in the cladding layer.
- Acceptance criteria — the cladding layer should be verified through hardness mapping, visual and magnetic particle inspection for surface defects, and ultrasonic testing for subsurface cracks or lack of fusion.
Study Insights and Reflections
This review effectively captures the transition in roll cladding technology from conventional arc welding methods toward advanced thermal spray and laser-based processes. The emphasis on dilution control as a primary quality determinant is well-founded and should guide process selection in any roll refurbishment program. The practical challenge that persists is the cost-benefit trade-off: while laser cladding and PTA offer superior metallurgical outcomes, their equipment and consumable costs remain significantly higher than conventional methods.
The most valuable insight for practicing engineers is that process selection must be driven by the specific service requirements of the roll — hardness, wear mechanism, operating temperature, and dimensional tolerance — rather than by a one-size-fits-all approach. A systematic evaluation framework that considers the full lifecycle cost, including cladding, grinding, and service life, is essential for making informed technology choices.