ERCOCR-A Filler Wire | ERCOCR-A Filler Wire CO6
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ERCoCr-A Filler Wire (Stellite® 6 / CO6 Cobalt Hardfacing Wire) Supplier in India
Nicorex Alloys is an ISO 9001 and ISO 14001 certified importer, stockist, and supplier of Stellite 6 hardfacing filler wire based in Mumbai, India. We stock this filler wire as classified under AWS A5.21 and ASME SFA 5.21.
Stellite 6 welding wire is a Co-Cr-W surfacing consumable for GTAW (TIG), OAW (oxy-acetylene), PTA and GMAW (MIG) hardfacing. The Co6 hardfacing rod deposits a CoCr matrix reinforced by M₇C₃ chromium carbides, producing HRC 38-45 on a two-layer undiluted overlay. The alloy contains 28-32% chromium, 4-6% tungsten, and 0.9-1.4% carbon with cobalt balance. This gives the cobalt alloy 6 TIG rod balanced galling resistance, impact toughness, cavitation erosion resistance and machinability with carbide tooling. No other Stellite grade matches that versatility. ERCoCr-A filler wire gives a hard, wear-resistant Co-Cr surface with HRC 38-45 in two layers and offers excellent galling, impact, cavitation and corrosion resistance while still being machinable. It is used for applying wear-resistant coatings on valve seats, pump internals, turbine parts and saw tips and is supplied with full test certificates.
Available forms include Stellite 6 bare rods (1.6-4.8 mm × 1000 mm) for TIG and OAW, continuous MIG/PTA wire spools (0.9-1.6 mm), and OAW cast rods up to 8.0 mm. Polarity is DCEN for GTAW with 100% argon. Every batch ships with MTC 3.1 per EN 10204, hardness reports and chemical analysis.
ERCoCr-A Cobalt 6 Filler Wire Technical Specifications
The table below details technical specifications for Stellite 6 hardfacing filler wire (ERCoCr-A bare rod and ERCCoCr-A continuous wire).
| AWS Classification |
Bare Rod: ERCoCr-A per AWS A5.21 Continuous Wire: ERCCoCr-A per AWS A5.21 Coated Electrode: ECoCr-A per AWS A5.13 |
|---|---|
| ASME SFA Specification | SFA 5.21 (rod/wire), SFA 5.13 (electrode) |
| UNS Number (rod/castings) | R30006 (rod/castings) / W73006 (electrode) / W73036 (wire) |
| AMS Specification | AMS 5788 (rod/wire), AMS 5387 & 5373 (castings) |
| Welding Processes | GTAW (TIG), OAW (oxy-acetylene), PTA, GMAW (MIG) |
| Polarity (GTAW) | DCEN (DC Electrode Negative) |
| Shielding Gas | 100% Argon (GTAW, GMAW, PTA); N/A for OAW |
| Welding Position | Primarily flat (1G/PA); vertical/overhead possible with reduced parameters |
| TIG Rod / OAW Rod Diameters | 1.6, 2.0, 2.4, 3.2, 4.0, 4.8 mm (1/16″ to 3/16″) |
| TIG/OAW Rod Length | 1000 mm standard (36″ in North America) |
| MIG/PTA Wire Diameters | 0.9, 1.0, 1.2, 1.6 mm |
| OAW Cast Rod Diameters | 3.2, 4.0, 4.8, 6.4, 8.0 mm |
AWS Classification Explained: ERCoCr-A
The AWS classification ERCoCr-A is explained below, showing what each letter and suffix means in the electrode designation.
| AWS Prefix | Detail | Description |
|---|---|---|
| ER | Bare Rod | Used for GTAW (TIG) and OAW (Gas/Oxy-Acetylene) welding. |
| Co | Cobalt-Base | The matrix provides excellent high-temperature strength. |
| Cr | Chromium | Provides both corrosion resistance and hard carbides. |
| -A (Suffix) | Stellite 6 / Co6 | The specific chemistry group (26–32% Cr, 3–6% W, 0.9–1.4% C). |
Chemical Composition of ERCoCr-A Weld Deposit (%)
Stellite 6 (ERCoCr-A) weld deposits follow the chemical composition limits defined in AWS A5.21. The table below lists standard composition ranges and typical undiluted deposit chemistry for cobalt-chromium hardfacing overlays.
| Specification | Carbon (C) | Chromium (Cr) | Tungsten (W) | Nickel (Ni) | Iron (Fe) | Molybdenum (Mo) | Silicon (Si) | Manganese (Mn) | Cobalt (Co) | Others total |
|---|---|---|---|---|---|---|---|---|---|---|
| AWS A5.21 Range (%) | 0.90–1.40 | 26.0–32.0 | 3.0–6.0 | 3.0 max | 3.0 max | 1.0 max | 2.0 max | 1.0 max | Balance | 0.50 max |
| Typical Deposit (%) | 1.30 | 30.6 | 5.5 | 1.0 | 1.0 | 0.1 | 1.3 | 0.09 | Balance (~59%) | — |
These values describe the chemistry of an undiluted, multi-layer Stellite 6 deposit as per AWS A5.21. The first layer picks up more iron because 15-40% of it mixes with the base metal. At least two layers are needed to reach the standard cobalt 6 composition.
Deposit Hardness and Mechanical Properties of Stellite 6 (ERCoCr-A)
ERCoCr-A is a hardfacing consumable. Performance is measured by deposit hardness, not tensile properties. Overlay hardness depends on layers, process and dilution.
| Specification | Hardness, 2-layer (GTAW) | Hardness, 2-layer (OAW) | Hardness, Single Layer | Hot Hardness @ 500°C | Tensile Strength | Compressive Strength | Elongation | Charpy Impact |
|---|---|---|---|---|---|---|---|---|
| Typical Value | HRC 38–45 (390–490 HV) | HRC 36–42 (380–450 HV) | HRC 28–38 (dilution-dependent) | ~HRC 30 (HV 300–320) | ~690 MPa (100 ksi) | ~1450 MPa (210 ksi) | <1% (brittle hardfacing) | Not applicable to overlay |
On carbon steel, the first layer is HRC 28–35 because it is highly diluted. The second layer reaches about HRC 36-42. A third layer can give HRC 40-45. Valve seats normally need at least two layers. OAW deposits are 2-4 HRC softer than GTAW. PTA can reach HRC 42-47.
Base Metal Compatibility for Stellite 6 (ERCoCr-A) Hardfacing Overlay
Stellite 6 cobalt hardfacing wire bonds with virtually all weldable ferrous and many non-ferrous substrates.
| Substrate Base Metal | ASME P-No. | Typical Preheat (°C) | Notes |
|---|---|---|---|
| Carbon steel (SA516 Gr.70, SA105, A36) | P-1 | 150–300 | Most common; 2-layer minimum |
| Low-alloy Cr-Mo (SA387 Gr.11, Gr.22) | P-4, P-5A | 250–350 | PWHT per base metal code |
| 9Cr-1Mo-V (Grade 91/P91) | P-15E | 250–300 | Butter layer may be needed |
| Austenitic SS (304, 316, 321, 347) | P-8 | None | Direct overlay; minimal dilution |
| Martensitic SS (410, CA6NM) | P-6 | 200–300 | Very common for valve bodies |
| Ferritic SS (405, 409) | P-7 | 150–200 | Less common |
| Duplex SS (2205) | P-10H | ≤80–150 | Control heat input; avoid sigma |
| Inconel 600/625 | P-43 | None | Direct overlay feasible |
| Monel 400 | P-42 | None | Direct overlay feasible |
ERCoCr-A hardfacing overlay is qualified per ASME Section IX QW-216 with F-Number F-71. WPS qualification requires chemical analysis and hardness testing per QW-453.
Recommended Welding Parameters for ERCoCr-A Cobalt 6 Hardfacing
The following table recommends welding parameters for ERCoCr-A Cobalt 6 for stable weld deposits.
| Rod Diameter (mm) | Amps (DCEN) | Volts | Gas Flow (L/min) | Position |
|---|---|---|---|---|
| 1.6 (1/16″) | 60–90 | 12–16 | 8–12 | Flat |
| 2.4 (3/32″) | 80–120 | 14–20 | 10–15 | Flat |
| 3.2 (1/8″) | 90–140 | 18–24 | 10–15 | Flat |
| 4.0 (5/32″) | 120–160 | 20–26 | 12–18 | Flat |
| 4.8 (3/16″) | 140–180 | 22–28 | 12–18 | Flat |
For OAW, use a neutral to slightly reducing flame and do not use flux. Preheat the part to 300-400°C and for carbon and low-alloy steel to 200-400°C, and keep the interpass temperature below 450°C. Let the part cool slowly under insulation. If a code requires it, perform stress relief at 595-650°C for 1-2 hours. Use stringer beads because wide weaving increases dilution. Small surface check cracks are normal in high-carbon cobalt alloys.
Key Wear and Metallurgical Properties of Stellite 6 (ERCoCr-A) Overlay
Five properties define Stellite 6 as the most specified cobalt hardfacing alloy: galling resistance, balanced abrasion + impact resistance, cavitation erosion resistance, machinability and corrosion resistance.
- Galling resistance: Cobalt’s FCC structure and Cr₂O₃ oxide film give ERCoCr-A outstanding self-mated anti-galling performance.
- Abrasion + impact: Co6 has enough M₇C₃ carbides for good abrasion resistance without crack sensitivity.
- Cavitation erosion: The cobalt matrix absorbs imploding bubble energy better than chromium carbide deposits.
- Machinability: ERCoCr-A deposits can be turned and milled with carbide tooling;
- Corrosion/oxidation: The 28-32% Cr provides oxidation resistance to ~700°C and seawater corrosion resistance (<0.05 mm/year at 22°C).
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Industrial Hardfacing Applications of ERCoCr-A Stellite 6 Filler Wire
ERCoCr-A is one of the most commonly used cobalt hardfacing materials for valves, pumps, and turbines.
- Oil & Gas: Gate valve seats/discs, ball valve seats, choke trim, BOP ram faces, Christmas tree internals and valve trim and wellhead equipment.
- Power Generation - Steam and Gas Turbine Components: Turbine blade erosion shields, shroud interlocks, governor valve seats, feedwater valve trim and boiler feed pump wear rings.
- Pump and Compressor Wear Surfaces: Shaft sleeves, bearing bushings, wear rings, impeller tips and reciprocating pump plungers. Self-mated Co6 surfaces provide exceptional anti-galling.
- Chemical, Petrochemical and Pharmaceutical Processing: Ideal for reactor mixer blades, agitator shafts, plug valve parts, and control valve cages used in processing plants.
- Lumber, Pulp and Paper - Saw Tips and Cutting Tools: Used on circular saw tips, band saw teeth, debarker knives and refiner disc segments for wear protection.
- Nuclear - Reactor Internals and Safety Valves: Used on CRDM wear surfaces, safety valve seats and primary pump wear rings in ASME Section III systems.
- Marine, Desalination and Food Processing: Used on seawater valve components, desalination pump internals, rotary valve seats and homogeniser seats in processing systems.
Storage and Handling of ERCoCr-A Cobalt Hardfacing Wire
ERCoCr-A welding wire is solid, not flux-cored, so you don’t need to worry about flux picking up moisture. The main risk is surface contamination. Even very small amounts of sulphur, lead, zinc, copper or other low-melting-point metals on the wire surface can cause severe hot cracking in nickel alloy welds.
- Store Stellite 6 TIG rods and OAW cast rods in original sealed tubes in a clean, dry environment (15–25°C, <60% RH)
- Store cobalt 6 wire spools in sealed packaging away from oil, grease, dust and grinding debris
- Handle rods with clean, lint-free gloves – fingerprint contamination causes porosity in overlay deposits
- Do not bend or kink cobalt hardfacing bare rods. They are relatively brittle
- Inspect rod/wire surface before use: must be clean, smooth, free of scale and foreign matter
- Keep cobalt alloy rods/wire away from carbon steel storage areas (iron contamination risk from contact or airborne grinding particles)
- Shelf life: Indefinite if stored properly in sealed original packaging
Available Forms, Diameters and Packaging of ERCoCr-A Stellite 6 Filler Wire
The following information outlines the available forms, diameter ranges, and packaging options for ERCoCr-A Stellite 6 filler wire.
| Product Form | Diameters (mm) | Length / Size | Packaging |
|---|---|---|---|
| Stellite 6 TIG Bare Rod (GTAW) | 1.6, 2.0, 2.4, 3.2, 4.0, 4.8 | 1000 mm (36″) | 2.5 kg, 5.0 kg tubes |
| OAW Cast Rod | 3.2, 4.0, 4.8, 6.4, 8.0 | 1000 mm (36″) | 5.0 kg tubes |
| Co6 MIG/PTA Wire (ERCoCr-A) | 0.9, 1.0, 1.2, 1.6 | Spools: D200, D300 | 5 kg, 12.5 kg, 15 kg |
| Bulk PTA/SAW Wire | 1.2, 1.6 | Drums | 25 kg, 50 kg drums |
How to Order ERCoCr-A Cobalt 6 Filler Wire from Nicorex Alloys
To ERCoCr-A cobalt wire, provide these details for a quotation:
- AWS Classification — ERCoCr-A per AWS A5.21 / ASME SFA-5.21
- Product Form — Specify one or more
- Diameter(s) Required — Cast rod typically 3.2, 4.0, 4.8 mm; wire typically 0.9, 1.2, 1.6 mm
- Quantity In kg
- Welding Process Intended — GTAW / OAW / GMAW / PTA / SMAW
- Target Deposit Hardness — Confirm ~38–44 HRC expected for ERCoCr-A (one layer on steel)
- Testing Requirements — Deposit hardness test, chemical analysis, PMI
- Certification — MTC 3.1 per EN 10204 (standard from Nicorex Alloys)
- Packaging Preference — Specify requirement
- Delivery — Address and timeline
Frequently Asked Questions
What is the price of ERCoCr-A (Stellite 6 / Co6) Cobalt Filler Wire per Kg in India?
ERCoCr-A is a high-value consumable. Price varies with size, product form, order quantity and cobalt market conditions. Please contact Nicorex Alloys for current prices and delivery times.
How many overlay layers of Stellite 6 are needed to reach full hardness with ERCoCr-A?
Use at least two layers. The first layer mixes with the base metal and gives about HRC 28–35. The second layer reaches about HRC 38–45. For very critical valve seats, you may specify three layers.
What is the difference between ERCoCr-A (Stellite 6) and ERCoCr-B (Stellite 12) Filler Wire?
ERCoCr-A (Stellite 6) is HRC 36-45 with lower carbon and tungsten, giving better impact resistance and allowing machining with carbide tools. ERCoCr-B (Stellite 12) is harder at HRC 45-51, with higher carbon and tungsten for stronger abrasion resistance, but it must be ground, not machined.
Can an ERCoCr-A bare rod be used for MIG (GMAW) Hardfacing?
No. Use ERCoCr-A only for manual TIG (GTAW) and oxy-acetylene (OAW) welding. For MIG (GMAW) and PTA, use ERCoCr-A (with a double C) as per AWS A5.21. Always weld with 100% argon, never with CO₂ gas mixtures.
What preheat is required before depositing ERCoCr-A Hardfacing on Carbon Steel?
Preheat carbon steels to 200-300°C, Cr-Mo steels to 250-350°C and martensitic stainless steels to 200-300°C. Austenitic stainless steels need no preheat. After welding, let the parts cool slowly under insulation.
Is ERCoCr-A Cobalt Hardfacing suitable for Sour Gas (NACE MR0175) valve service?
ERCoCr-A is generally accepted under NACE MR0175/ISO 15156. This makes it suitable for sour gas valve service.
Does Nicorex Alloys stock ERCoCr-A in both TIG Rod and PTA wire Forms?
Yes. Nicorex Alloys stocks ERCoCr-A TIG rods (1.6-4.8 mm) and ERCCoCr-A wire (0.9-1.6 mm), all batch-tested with MTC 3.1. Matching ECoCr-A electrodes and Stellite 6 powder are also available from stock.
When not to use ERCoCr-A (Stellite 6) Cobalt Filler wire?
Avoid ERCoCr-A for severe low-angle abrasion. Don’t use ERCoCr-A above 500°C, as it softens above about 500 °C. Avoid using ERCoCr-A where cobalt-60 activation is an issue. Do not use ERCoCr-A for structural welds.