CLADDING TECHNOLOGY SHANXI CO., LTDResearch and Application of Cladding Materials for Rolling Guide Plates
Literature Overview
This study, published in Powder Metallurgy Industry in 2009 by Wang Fengping, Li Gang, and Li Guoping from Laiwu Vocational and Technical College and Laiyang District Science and Technology Bureau, addresses a critical industrial challenge in steel rolling mill operations. Rolling guide plates (also called roll guides or guide shoes) are consumable components positioned between the rolls and the workpiece to control the lateral position and shape of the rolled strip. These components endure extreme conditions including high temperatures, abrasive contact with hot steel, mechanical impact, and thermal cycling. The original carbon steel or low-alloy steel guide plates suffer from rapid wear, requiring frequent replacement, which leads to production downtime and increased operational costs.
The research focuses on developing and applying appropriate cladding materials to extend the service life of rolling guide plates through weld overlay technology. This is a classic case of surface engineering applied to heavy industrial equipment, where the goal is to combine the toughness and strength of the base material with the wear resistance and heat resistance of the overlay layer.
Core Technical Content
Selection of Cladding Materials
The selection of cladding materials for rolling guide plates requires balancing multiple competing properties. The overlay material must exhibit:
- High hardness at elevated operating temperatures (typically 800-1200 °C for hot rolling)
- Excellent abrasive wear resistance against hot steel strip
- Thermal shock resistance to withstand rapid temperature changes
- Good bonding strength to the base material
- Resistance to thermal fatigue cracking
Common candidate materials for this application include:
| Material Category | Typical Grades | Key Properties | Application Suitability |
|---|---|---|---|
| High-speed steel | W6Mo5Cr4V2, W12Cr4V | High red hardness, wear resistance | Moderate temperature service |
| Stellite-type alloys | Stellite 6, Stellite 21 | Excellent hot wear resistance, thermal shock tolerance | High-temperature hot rolling |
| Iron-based composite | WC-Co, Cr3C2-Ni-Cr | High hardness, abrasion resistance | Cold rolling, moderate temperature |
| Nickel-based alloys | Inconel 601, Hastelloy X | Superior thermal stability, corrosion resistance | Extreme thermal cycling |
| Cr-Mo-V steels | 5CrMoV, 4Cr5MoSiV | Cost-effective, good hot hardness | Warm rolling operations |
Welding Process Selection
For rolling guide plate cladding, the following processes are most commonly considered:
- Submerged Arc Welding (SAW) Overlay — High deposition rate, suitable for thick overlay layers (3-8 mm), good for large plates. Requires preheating and interpass temperature control.
- Gas Metal Arc Welding (GMAW) Overlay — Moderate deposition rate, good process control, suitable for repair and moderate-thickness overlay (1-5 mm).
- Flux-Cored Arc Welding (FCAW) Overlay — High deposition rate with self-shielded flux cored wire, suitable for field repair conditions.
- Plasma Transferred Arc (PTA) Cladding — Excellent dilution control (typically 10-20%), good microstructure refinement, suitable for high-alloy overlay layers.
- Hot-Wire TIG Cladding — Precise deposition control, low heat input, suitable for thin, high-quality overlay layers.
Typical Process Parameters
For a typical hot rolling guide plate cladding application using Stellite-type materials:
| Parameter | Range | Rationale |
|---|---|---|
| Base material preheat | 200-350 °C | Reduce residual stress, prevent cracking |
| Interpass temperature | 250-400 °C | Maintain ductility, prevent cold cracking |
| Welding current (GMAW) | 200-350 A | Adequate penetration, controlled dilution |
| Welding speed | 200-400 mm/min | Balance deposition rate and cooling rate |
| Wire feed speed | 3.0-6.0 m/min | Match with travel speed for uniform bead |
| Number of passes | 2-4 | Achieve target overlay thickness |
| Post-weld heat treatment | 650-750 °C × 2h | Relieve stress, refine microstructure |
Engineering Practice Considerations
Defect Analysis and Countermeasures
The following table summarizes common defects encountered during guide plate cladding and their countermeasures:
| Defect Type | Root Cause | Countermeasure |
|---|---|---|
| Cracking at fusion line | High dilution, high cooling rate | Preheat base material, use lower dilution process, add dilution buffer layer |
| Porosity | Flux contamination, moisture | Dry flux, clean surfaces, proper gas shielding |
| Spalling/delamination | Poor bonding, thermal stress | Optimize interpass temperature, ensure surface preparation |
| Excessive dilution | High heat input, thick base | Use PTA, hot-wire TIG, or reduce current |
| Microcracking in overlay | Segregation, high carbon content | Post-weld stress relief, select appropriate composition |
Quality Control Requirements
Non-destructive testing (NDT) for guide plate cladding typically includes:
- Magnetic Particle Testing (MT) — Detection of surface and near-surface cracks in each pass
- Ultrasonic Testing (UT) — Detection of internal defects, bonding quality
- Hardness Testing — Verification of overlay hardness profile (typically HV 400-600 for wear-resistant overlays)
- Macrographic Examination — Verification of overlay thickness uniformity, dilution control
Case Study: Application in Hot Strip Mill
In a hot strip mill application, the original carbon steel guide plates had a service life of approximately 4-6 hours before requiring replacement due to wear. After applying a two-pass Stellite 6 overlay using GMAW process with a dilution buffer layer of nickel-based alloy:
- Service life increased to 18-24 hours (4-5 times improvement)
- Overlay thickness maintained at 4-5 mm after service
- No spalling or cracking observed during service
- Overall maintenance cost reduced by approximately 60%
Study Insights and Reflections
This research represents an important contribution to the practical application of surface engineering in the steel industry. The key insight is that material selection must be driven by the specific operating conditions rather than simply maximizing hardness. In hot rolling applications, thermal shock resistance is often more critical than room-temperature hardness, which is why Stellite-type alloys outperform high-carbon cementation-type materials.
The study also highlights the importance of process optimization in achieving reliable cladding results. The dilution rate between the base material and overlay significantly affects the final properties. In practice, achieving a dilution rate below 20% for nickel-based overlays on carbon steel bases requires careful process selection and parameter control. The use of a transition layer or buffer layer is often necessary when the composition difference between base and overlay is large.
From a manufacturing perspective, the economic evaluation of cladding must consider not only the material and welding costs but also the reduction in production downtime. For high-throughput rolling mills, the cost of guide plate replacement and associated downtime often far exceeds the cost of the cladding operation itself, making this a highly economical surface engineering solution.
The 2009 publication date of this study is notable, as it reflects the growing maturity of surface engineering practices in China's steel industry during that period. Subsequent developments in hot-wire TIG and laser cladding technologies have further improved the quality and reliability of guide plate cladding, but the fundamental principles established in this research remain highly relevant to current engineering practice.