TOKO 2535Nb NiCr Alloy Welding Rods (Nb Stabilized)
Premium nickel-chromium electrodes with niobium addition, delivering exceptional resistance to oxidation, sulfidation, and carburization at continuous elevated temperatures. The weld metal retains strength and ductility even after prolonged thermal exposure.
Key Advantages
- Niobium stabilization — prevents chromium carbide precipitation, maintains corrosion resistance in HAZ.
- Exceptional high-T strength — reliable service up to 1000°C (1832°F) in oxidizing and carburizing atmospheres.
- Oxidation & sulfidation resistant — ideal for aggressive petrochemical environments.
- All-position usability — flat, horizontal, and vertical-up (for diameters ≤3.2mm).
- Self-detaching slag — minimal post-weld cleaning, smooth bead appearance.
- Available diameters: 2.5mm (0.098"), 3.2mm (0.125"), 4.0mm (0.157").
Performance Benefits for Critical High-Temperature Assets
- Arc Stability: Smooth, stable arc with fine droplet transfer.
- Creep Resistance: Nb refines grain structure, improves long-term creep strength.
- Carburization Resistance: High Ni/Cr ratio minimizes carbon absorption.
- PWHT flexibility: Can be used as-welded or solution annealed.
- Dissimilar joints: Excellent for welding Ni-alloys to stainless or heat-resistant steels.
Primary Industrial Applications
Trusted in critical high-temperature processes worldwide.
Furnace & Heat Treat
Radiant tubes, muffles, annealing covers, and furnace rollers – resists thermal fatigue.
Petrochemical Reformers
Catalyst tubes, outlet manifolds, pigtails – withstands carburization and thermal cycling.
Power Generation
Boiler superheaters, reheaters, coal-fired plant components – oxidation resistance up to 1000°C.
Waste Incineration
Grates, liners, and flue gas handling – resists sulfidation and chlorine attack.
Additional Applications & Industries
- Heat exchanger tubing for high-temp processes
- Aerospace thermal processing equipment
- Ammonia reformer assemblies
- Ceramic-lined pipe attachments
- Repair welding of HP-modified alloys
- Fluidized bed combustors
- Glass manufacturing electrodes
Technical Specifications (Typical)
Chemical Composition (wt.%, AWS A5.11 type ENiCrFe-2/3)
| Element | Typical (2535Nb) | Requirement |
|---|---|---|
| Nickel (Ni) | 55–60% | ≥55% (balance) |
| Chromium (Cr) | 23–27% | 20–28% |
| Niobium (Nb) | 2.0–3.5% | 1.5–4.0% |
| Manganese (Mn) | 2.0–3.5% | ≤4.0% |
| Iron (Fe) | ≤8.0% | ≤10% |
| Silicon (Si) / Carbon (C) | 0.3 / 0.03 | ≤0.5 / ≤0.08 |
Mechanical Properties (as-welded / after PWHT)
| Property | Value (RT) | At 900°C |
|---|---|---|
| Tensile Strength (MPa) | 620–700 | ≥180 (creep rupture) |
| Yield Strength (MPa) | 400–460 | — |
| Elongation (%) | 32–40 | — |
| Hardness (HB) | 170–210 | — |
| Oxidation scaling temp | Continuous: 1000°C / intermittent: 1150°C |
Recommended Welding Parameters (SMAW, AC/DC+)
| Diameter (mm) | Current (A) | Voltage (V) | Interpass °C |
|---|---|---|---|
| 2.5 mm | 60–90 | 22–25 | 150 max |
| 3.2 mm | 90–130 | 23–27 | 150 max |
| 4.0 mm | 130–170 | 25–28 | 200 max |
* Preheat only if base metal requires (typically 150-250°C for thick sections). Post-weld heat treatment optional, usually 900-1050°C solution anneal if needed.
Certifications, Safety & Storage
- Classification: Meets AWS A5.11 (ENiCrFe-2/3) and similar ISO 14172.
- Safety: Use adequate fume extraction – nickel/chromium compounds. Wear proper PPE.
- Storage: Keep in original sealed packaging; re-dry at 300°C/1h if exposed >4h.
Batch-specific MTCs traceable to EN 10204 3.1.
Why Choose TOKO 2535Nb?
- 🔬 Niobium stabilized — prevents intergranular corrosion after high-T service.
- ⚡ Reliable arc characteristics — even in positional welding.
- 🧪 Proven in reformer tubes — extensive field history in ethylene furnaces.
- 📦 Globally stocked — rapid delivery for maintenance turnarounds.