CLADDING TECHNOLOGY SHANXI CO., LTDNickel-Based Superalloy Cladding Electrode Application on Width-Control Press Module Study Note
Literature Overview and Technical Background
Width-control press modules (定宽压力机模块) in steel rolling mills are subjected to extreme conditions including high contact pressure (up to 4 GPa), elevated temperatures (up to 600°C), and severe abrasive wear from hot steel strip. Conventional tool steels and high-speed steels used for these modules typically have limited service life, requiring frequent replacement and causing significant production downtime. This study investigates the application of a novel nickel-based superalloy cladding electrode for extending the service life of width-control press modules, evaluating both the cladding process and the resulting tribological performance.
Core Technical Content
Nickel-Based Superalloy Electrode Characteristics
The novel electrode is designed based on the IN625 (UNS N06625) superalloy system with modifications for weldability and cladding performance:
| Component | Electrode Composition (wt%) | Pure IN625 Reference |
|---|---|---|
| Ni | Balance (≥55%) | Balance |
| Cr | 18–22% | 20–23% |
| Mo | 8–10% | 8.0–10.0% |
| Nb | 4–6% | 4.0–5.5% |
| Fe | 4–6% | ≤5.0% |
| C | ≤0.10% | ≤0.10% |
| Al | 0.2–0.5% | 0.2–0.7% |
| Ti | 0.5–1.0% | ≤1.15% |
Cladding Process Parameters
| Parameter | Specification | Rationale |
|---|---|---|
| Preheat temperature | 150–200°C | Reduce thermal gradient, prevent cracking |
| Interpass temperature | ≤ 250°C | Maintain microstructure integrity |
| Welding current (GTAW) | 150–220 A | Adequate penetration without excessive dilution |
| Welding speed | 80–150 mm/min | Balance deposition rate and quality |
| Shielding gas | Ar 98% / He 2% | Enhance arc stability and penetration |
| Layer thickness per pass | 1.5–2.5 mm | Ensure proper fusion without cracking |
| Total overlay thickness | 5–10 mm | Provide adequate machining allowance |
Microstructure and Properties of Cladding Layer
The nickel-based superalloy overlay exhibits the following characteristics:
- Microstructure: Equiaxed γ matrix with γ' (Ni₃(Al,Ti)) precipitates and carbides (NbC, MoC) at grain boundaries. The average grain size is 50–150 μm in the as-welded condition.
- Hardness: HV 280–350 in as-welded condition; HV 320–380 after aging treatment (980°C/4h + 720°C/8h + 620°C/8h).
- Impact toughness: Charpy impact energy of 45–65 J at room temperature, significantly better than conventional tool steels under similar hardness.
- Thermal stability: Hardness retention above 90% after 100 hours at 600°C, demonstrating excellent thermal stability.
- Wear resistance: Pin-on-disc testing shows 2–3 times the wear life of H13 tool steel under simulated press module conditions.
Engineering Application and Performance
Service Performance Comparison
| Performance Metric | H13 Tool Steel Module | Ni-Superalloy Clad Module | Improvement |
|---|---|---|---|
| Service life (strip tons) | 8,000–12,000 | 25,000–35,000 | 200–250% |
| Replacement frequency (per year) | 8–12 times | 2–3 times | 70–75% reduction |
| Surface roughness after service | Ra 3.5–5.0 μm | Ra 1.5–2.5 μm | 50% improvement |
| Galling resistance | Poor | Excellent | Qualitative improvement |
| Thermal fatigue resistance | Moderate | Excellent | Significant improvement |
Critical Manufacturing Considerations
- Substrate preparation: The base module material (typically H13 or similar hot-work tool steel) must be ground to remove surface decarburization and contamination. A roughness of Ra 6.3–12.5 μm is optimal for mechanical interlocking.
- Dilution management: Despite the high melting point of the nickel alloy, dilution from the steel substrate can still affect the first 0.5–1.0 mm of the overlay. A minimum of 3 mm overlay thickness is recommended to ensure the functional surface is fully within the nickel alloy composition range.
- Cracking prevention: Nickel-based superalloys are susceptible to solidification cracking due to their narrow solidification range. The following measures are essential:
- Add 0.2–0.5% sulfur to promote grain boundary sliding
- Use a slightly higher nickel content to widen the solidification range
- Maintain interpass temperature below 250°C
- Avoid excessive heat input per pass
- Post-weld machining: The overlay must be machined to precise dimensional tolerances (typically ±0.05 mm for press modules). The nickel alloy's work-hardening tendency requires careful selection of cutting parameters: low cutting speed (30–50 m/min), high feed rate, and abundant coolant.
Study Insights and Practical Implications
The most impactful finding from this study is the dramatic improvement in module service life achieved through nickel-based superalloy cladding—approximately 200–250% longer than conventional H13 tool steel modules. When considering the high cost of production downtime in continuous rolling mills, this improvement translates to substantial economic benefits, with estimated ROI periods of less than 12 months for high-volume mills.
A particularly valuable insight is the galling resistance demonstrated by the nickel-based overlay. In width-control press applications, galling (adhesive wear) between the module surface and the hot steel strip is a major failure mode. The nickel-chromium-molybdenum alloying system provides an effective diffusion barrier that prevents iron-nickel intermetallic compound formation at the contact interface, fundamentally changing the wear mechanism from adhesive to abrasive.
From a process development perspective, the study highlights the importance of the aging treatment in maximizing the cladding layer properties. While the as-welded overlay already provides significant improvement over the base material, the full aging treatment (980°C/4h + 720°C/8h + 620°C/8h) optimizes the γ' precipitate distribution, improving both hardness and thermal stability. However, this treatment must be carefully controlled to avoid excessive grain growth at the overlay-substrate interface, which could compromise bond strength.