AWS Class ERZR-4 MIG & TIG
ERZr-4 TIG Filler Rod & MIG Wire Supplier in India
Nicorex Alloysis an ISO 9001 and ISO 14001 certified Mumbai-based stockist, importer, and supplier of ERZr-4 zirconium alloy welding wire, classified under AWS A5.24 / ASME SFA-5.24.
ERZr-4 is a zirconium-based welding filler metal used for joining zirconium alloys, providing exceptional corrosion resistance in highly acidic environments. The 2.0-3.0% Nb addition provides solid-solution strengthening, stabilises the beta (BCC) phase below ~920°C (1688°F) to form a two-phase alpha-beta microstructure, and improves hydrogen absorption resistance by promoting uniform hydride distribution. Oxygen tolerance is high at 0.18% max, adding further strength. Stress relief at 580-620°C (1076-1148°F) must be completed within 14 days of welding per ASME Code. This requirement is not optional. Higher ASME Code design stress allowables, which allow thinner vessel walls at equivalent design pressures, reduce material cost for zirconium pressure vessel fabrication. It delivers approximately 45% high tensile strength for around 552 MPa (80 ksi) tensile and 379 MPa (55 ksi) yield, while preserving zirconium’s excellent corrosion resistance in reducing acids like HCl and H₂SO₄.
ERZr-4 wire is available in TIG rod diameters of 1.6, 2.0, 2.4, and 3.2 mm and MIG spool diameters of 0.8, 1.2, and 1.6 mm. This alloy is commonly used in ASME pressure vessels that handle corrosive chemicals, in pressure tubes for CANDU nuclear reactors, in equipment for high-pressure acid processing, in injection wells, and in parts for geothermal energy. Every supply is backed by EN 10204/3.1B certificates from mill tests and interstitial analysis.
ERZr-4 Zirconium Alloy Welding Wire Specifications
The table below lists ERZr-4 specifications, including classification, processes, shielding gas, diameters, and other requirements.
| AWS Classification | A5.24 ERZr-4 per AWS A5.24 |
|---|---|
| UNS Designation | R60705 |
| Welding Processes | GTAW, GMAW, PAW |
| Shielding Gas | 100% Argon (99.995% purity) |
| TIG Rod Diameters | 1.6, 2.0, 2.4, 3.2 mm (0.063, 0.079, 0.094, 0.126 in) |
| MIG Wire Diameters | 0.8, 1.2, 1.6 mm (0.030, 0.047, 0.063 in) |
| Rod Length | 914 mm or 1000 mm |
AWS Classification Explained: ERZr-4 (TIG/MIG Wire)
Refer to the following table for a detailed breakdown of the AWS classification and technical designations for ERZr-4 filler metal.
| Designator | Meaning |
|---|---|
| E | Electrode |
| R | Rod |
| Zr | Zirconium-base alloy |
| 4 | Grade 4: Zr-2.5Nb alloy (UNS R60705) |
ERZr4 denotes a Zirconium-base alloy electrode/rod. Specifically, Grade 4 (UNS R60705) is a Zr-2.5Nb alloy, offering higher tensile strength than Grade 2. Engineers specify this filler for superior corrosion resistance in high-pressure, aggressive chemical processing environments.
Chemical Composition of ERZr-4 Weld Deposit (%)
Consult the following table for the standard chemical composition and elemental limits for the ERZr-4 all-weld metal deposit.
| Specification | Zirconium + Hafnium (Zr+Hf) | Hafnium (Hf) | Niobium (Nb) | Iron + Chromium (Fe+Cr) | Hydrogen (H) | Nitrogen (N) | Carbon (C) | Oxygen (O) |
|---|---|---|---|---|---|---|---|---|
| AWS A5.24 Req. (%) | 95.5 min | 4.5 max | 2.0–3.0 | 0.20 max | 0.005 max | 0.025 max | 0.050 max | 0.18 max |
Niobium (2.0-3.0%) stabilises the beta phase, creating a stronger alpha-beta microstructure. The 0.005% H limit is critical: hydrogen above this level causes zirconium hydride embrittlement in service.
All-Weld-Metal Mechanical Properties of ERZr-4 (Zircadyne 705)
The table below shows the mechanical property parameters and tensile strength norms for ERZr-4 all-weld metal.
| Specification | Tensile Strength | Yield Strength (0.2% Offset) | Elongation |
|---|---|---|---|
| AWS A5.24 Minimum | 552 MPa (80,000 psi) | 379 MPa (55,000 psi) | 16% |
Tensile exceeds ERZr-2 all-weld values by approximately 45% (80 ksi vs 55 ksi) and yield by approximately 83% (55 ksi vs 30 ksi). Higher ASME allowables reduce wall thickness in code-stamped zirconium pressure vessels.
Base Metal Compatibility for ERZr-4
Refer to the following table for ERZr-4 base metal compatibility and matching zirconium grades.
| Base Metal | UNS | P-Number | Notes |
|---|---|---|---|
| Zircadyne 705 (Zr 705) | R60705 | P-62 | Matching filler |
| Zircadyne 702 (Zr 702) | R60702 | P-61 | Over-matched – with engineering approval only |
Zirconium cannot be fusion welded to steel, titanium, nickel, or copper alloys. Explosive bonding is required for dissimilar metal transition joints.
Recommended Welding Parameters for ERZr-4 MIG & TIG Filler Metal
Consult the following table for the optimal amperage, voltage, and gas settings required for ERZr-4 applications.
| Diameter | Current (A) | Shielding Gas Requirements | Equipment Notes |
|---|---|---|---|
| 1.6 mm | 60–120 | 100% High-Purity Argon | Requires back purge and trailing shield. |
| 2.4 mm | 100–180 | 100% High-Purity Argon | Mandatory back purge is required. |
| 3.2 mm | 140–250 | 100% High-Purity Argon | Glove box preferred for critical joints. |
ERZr-4 welding requires 99.995% pure Argon; any oxygen or nitrogen contamination will ruin the weld. Buyers should ensure operators have trailing shields or glove boxes to maintain the strict gas coverage needed for zirconium.
Stress relief within 14 days of welding is mandatory at 580-620°C. Reject any bead darker than light gold on colour inspection.
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Industrial Applications of ERZr-4 Zirconium Alloy Welding Wire
ERZr-4 is widely applicable in the following industries:
- ASME Pressure Vessels: Used to build corrosive acid reactors, columns, and heat exchangers. Because this alloy offers higher design stress limits, engineers can specify thinner vessel walls, significantly reducing both total material weight and cost.
- Nuclear Industry: Setting the global standard for CANDU heavy-water reactor pressure tubes. They need this filler to produce and repair these parts because its chemical nature prevents hydrogen absorption in radiation-heavy areas.
- High-Pressure Acid Equipment: It is used in piping and heat exchanger applications where concentrated sulfuric and hydrochloric acids are used. It is preferred over other materials where greater mechanical strength is required to withstand extreme pressure and pulsating conditions.
- Injection and Deep Well Disposal: Used in special wells that get rid of dangerous, corrosive waste fluids. It is specified for its ability to maintain structural integrity while exposed to aggressive chemicals at elevated underground pressures.
- Geothermal Energy Equipment: Found in components exposed to hot, mineral-rich geothermal brines. It is chosen because its corrosion resistance outperforms both titanium and nickel alloys in these specific high-temperature, salt-heavy environments.
Storage & Handling of ERZr-4 Welding Wire
ERZr-4 storage follows ERZr-2 protocol with one critical addition: stress relief within 14 days of welding is mandatory.
- Store in sealed packaging, separate from other metals
- Clean wire with acetone before welding; use lint-free gloves only
- Apply pyrophoric fire precautions: zirconium chips and dust are flammable
- Complete stress relief at 580-620°C within 14 days of welding, with no exceptions
- MTC 3.1 per EN 10204 with Nb, Hf, and full interstitial analysis accompanies each shipment
Available Forms, Diameters & Packaging of ERZr-4 Zirconium Alloy Wire
ERZr-4 is supplied in two primary product forms: TIG rods for GTAW/PAW and MIG wire spools for GMAW.
| Form | Diameter | Packaging |
|---|---|---|
| TIG Rod (GTAW) | 1.6, 2.0, 2.4, 3.2 mm | 5 kg sealed tubes, 914 mm or 1000 mm length |
| MIG Wire Spool (GMAW) | 0.8, 1.2, 1.6 mm | 5 kg or 10 kg vacuum-sealed spools |
Surface condition: bright pickled or polished. Custom spool sizes and diameters available on request with applicable lead times.
How to Order ERZr-4 Zirconium Alloy Welding Wire from Nicorex Alloys
Nicorex Alloys stocks ERZr-4 (Zr-2.5Nb / UNS R60705) in Mumbai. To receive a quotation, please provide 10 details:
- AWS Classification: ERZr-2 per AWS A5.24 / ASME SFA-5.24
- Diameter: 1.6 mm / 2.4 mm / 3.2 mm; cut lengths 914 mm / 1000 mm
- Quantity: Specify kg or number of tube packs
- Testing / Certification: MTC EN 10204 3.1/3.2; PMI Report; ASTM B551 compliance; TPI
- Base Metal: Zirconium 702 UNS R60702 / Zr704 / Zr705 - specify grade
- Material Grade: Zr 702; UNS R60702; W.Nr. 3.7701; AWS A5.24: ERZr-2
- Third-Party Approvals: TÜV / BV / DNV (chemical / nuclear / offshore) - specify sector
- Applicable Code: ASME IX; ASME B31.3; ASME Section VIII - specify
- Delivery: Domestic / International - specify port or address
- Remarks: 99.999% pure Ar shielding and back purge mandatory; confirm Zr702 base metal - nuclear or chemical service
Frequently Asked Questions
What is the role of niobium in ERZr-4?
Niobium (2.0-3.0%) provides four benefits:
- solid-solution strengthening, raising tensile strength from 379 MPa to 552 MPa (55 to 80 ksi)
- beta-phase stabilisation creating a stronger alpha-beta microstructure
- improved hydrogen and deuterium absorption resistance through uniform hydride distribution, and
- better formability at equivalent strength compared to oxygen-strengthened CP zirconium.
Is ERZr-4 used in CANDU nuclear reactors?
Yes. Zr-2.5Nb is the standard pressure tube material in CANDU (Canadian Deuterium Uranium) reactors. ERZr-4 is the matching filler for fabrication and re-tubing. Nb improves resistance to deuterium absorption under high neutron flux in the reactor core.
Can ERZr-2 be used instead of ERZr-4 for Zircadyne 705 base metal?
No, not for structural or pressure-retaining joints. ERZr-2 produces an under-matched joint at 55 ksi versus the 80 ksi of Zr 705. This fails ASME Section IX requirements for pressure-retaining welds. ERZr-2 is permitted only for non-structural attachments with explicit engineering approval.
What spool sizes are available for ERZr-4?
TIG rods are supplied in 914 mm or 1000 mm lengths, 5 kg per sealed tube. MIG spools are available in 5 kg and 10 kg vacuum-sealed reels. Every pack ships with EN 10204/3.1B MTC confirming Nb content, Hf content, and full interstitial analysis.
When not to use ERZr-4 Welding Filler Wire?
ERZr-4 welding filler wires should not be used for:
- Nitric acid above 50% concentration (same restriction as ERZr-2)
- Hydrofluoric acid (HF dissolves the protective ZrO₂ layer)
- Fusion welding to steel, titanium, nickel, or copper alloys
- Not without mandatory stress relief within 14 days of welding
- Not where ERZr-2 strength is adequate (avoid unnecessary cost premium)
- Shielding gas containing CO₂, O₂, or N₂
- Not without pyrophoric fire precautions for chips and dust