AWS Class E2594-16 Welding Electrodes
Super Duplex Steel E2594-16 Welding Electrode Supplier in Mumbai, India
Nicorex Alloys is a specialist supplier and stockist of E2594-16 super duplex stainless steel welding electrodes, operating from our Mumbai, India, warehouse. We are ISO 9001 and ISO 14001 certified, with batch-tested inventory ready for dispatch.
E2594-16 welding electrodes make super duplex stainless steel with a PREN greater than 40 by fusing 25% chromium, 10% nickel, 4% molybdenum, and 0.25% nitrogen. This electrode has been specifically engineered for the welding of UNS S32750 (2507), S32760 (Zeron 100), S31260, S32550, and A890 castings, with the addition of 2-3% nickel over-alloying for controlling ferrite content between FN 35-50. The mechanical properties indicate that the minimum tensile strength for the weld metal is 760 MPa (110 KSI) with a minimum elongation of 15%. The wire sizes available for the E2594-16 electrode are 2.4mm (3/32″), 3.2 mm (1/8″), and 4.0 mm (5/32″). This product can be used for all positions (F, V, OH, H) with DCEP.
This welding rod meets the requirements of AWS A5.4, ASME SFA 5.4, and EN ISO 3581-A (E 25 9 4 N L R 3 2) and is classified as ASME IX F-5 / A-8. Key sectors served: offshore oil and gas, subsea, desalination, chemical processing, and marine infrastructure. Every batch ships with MTC 3.1 per EN 10204 and all-weld-metal test reports. It ensures that high PREN values translate into maximum structural integrity and long-term resistance against localised corrosion in extreme environments.
E2594-16 Coated Electrode Specifications
The following are the full technical specifications for the E2594-16 super duplex stainless steel welding electrode per AWS A5.4:
| AWS Classification | E2594-16 |
|---|---|
| ASME SFA Specification | SFA 5.4 |
| EN ISO Equivalent | EN ISO 3581-A: E 25 9 4 N L R 3 2 |
| Welding Process | SMAW (Shielded Metal Arc Welding) |
| Coating Type | Rutile (TiO₂-based) |
| Current / Polarity | DCEP or AC |
| Welding Positions | All positions (F, V, OH, H) |
| ASME Section IX F-Number | F-5 |
| ASME Section IX A-Number | A-8 |
| Available Diameters | 2.4, 3.2, 4.0 mm (3/32″, 1/8″, 5/32″) |
| Electrode Length | 300-350 mm (12″-14″) |
| Ferrite Number (FN) | 35-50 (as-welded) |
| Service Temperature | Up to 300°C (572°F) continuous |
| PREN (Weld Deposit) | ≥40 |
| NACE MR0175 / ISO 15156 | Compliant |
| Deposition Efficiency | ~60-65% |
Overview of E2594-16 AWS A5.4 Classification
The E2594-16 classification identifies this consumable’s alloy chemistry, process suitability, and coating type in a single alphanumeric code under AWS A5.4.
| Symbol | Meaning |
|---|---|
| E | Electrode; designed for SMAW (shielded metal arc welding) |
| 25 | Nominal 25% chromium in the weld deposit (super duplex range) |
| 9 | Nominal 9-10% nickel; over-alloyed vs base metal for ferrite balance |
| 4 | Nominal 4% molybdenum in the weld deposit |
| -16 | Rutile (TiO₂) coating; AC or DCEP, all-position, operator-friendly |
“2594” matches the super duplex composition: 25Cr-9Ni-4Mo. Compared to “2209” (22Cr-9Ni-3Mo), greater Cr, Mo, and N concentrations raise PREN from ~35 to ≥40. The “4” in 2594 denotes that the molybdenum concentration is double that of E2209, causing stronger pitting resistance.
A “-15” basic-coated variant (E2594-15) also exists, offering improved low-temperature Charpy toughness but requiring DCEP polarity only. Both -16 and -15 variants deposit identical weld metal chemistry. The coating type affects arc behaviour and operability, not the deposited metal composition.
Weld Deposit Chemical Composition of E2594-16 (%)
The chemical composition of E2594-16 weld deposit per AWS A5.4 is engineered to exceed PREN 40, the threshold that defines super duplex corrosion performance.
| Element | Carbon (C) | Chromium (Cr) | Nickel (Ni) | Molybdenum (Mo) | Nitrogen (N) | Manganese (Mn) | Silicon (Si) | Copper (Cu) | Phosphorus (P) | Sulfur (S) | Iron (Fe) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| AWS A5.4 Spec Range (wt%) | 0.04 max | 24.0-27.0 | 8.0-10.5 | 3.5-4.5 | 0.20-0.30 | 0.5-2.0 | 1.00 max | 0.75 max | 0.04 max | 0.03 max | Balance |
| Typical Deposit | 0.03 | 25.5 | 10.0 | 4.0 | 0.25 | 0.7 | 0.6 | — | — | — | Balance |
PREN calculation: %Cr + 3.3×%Mo + 16×%N = ~42.7, exceeding the ≥40 criterion. Nitrogen at 0.20-0.30% (vs. 0.08-0.20% for E2209) drives the higher PREN and stabilises austenite against excessive ferrite. Nickel is purposefully over-alloyed (8.0-10.5% vs 7.0-8.0% in wrought S32750) to compensate for welding nitrogen loss.
For reference: E2209-16 deposits a PREN of ~35 versus E2594-16 at ~42. This 20% improvement corresponds to a critical pitting temperature (CPT) that is approximately 40°C higher. Actual deposit chemistry depends on welding parameters, dilution, and base metal composition.
All-Weld-Metal Mechanical Properties of E2594-16
The E2594-16 super duplex weld deposit achieves higher minimum tensile strength than standard duplex (E2209) electrodes, reflecting the increased alloy content.
| Property | Ultimate Tensile Strength | Yield Strength (0.2%) | Elongation | Charpy Impact (+20°C) | Charpy Impact (-40°C) | Hardness | Ferrite Number (FN) |
|---|---|---|---|---|---|---|---|
| AWS A5.4 Minimum | 760 MPa (110 ksi) | — | 15% | — | — | — | — |
| Typical Values | 800-850 MPa | 650-700 MPa | 18-22% | 80-100 J | 50-70 J | ≤30 HRC | 35-50 |
UTS minimum of 760 MPa is 10% higher than E2209 (690 MPa), permitting thinner super duplex pressure equipment walls. 18-22% elongation is suitable for most code applications, compared to 20% for E2209. Project-specific chart impact testing at -20°C and -46°C occurs offshore.
Base Metal Compatibility & P-Number Matrix for E2594-16
E2594-16 is specifically formulated for welding super duplex stainless steels and related high-alloy grades. Its overmatched PREN keeps the weld deposit from becoming the weakest link in the joint.
Primary Base Metals (Similar Joints)
| Base Metal | UNS | Common Name | ASME P-No. |
|---|---|---|---|
| 2507 | S32750 | Super Duplex 2507 | P-10H Group 1 |
| Zeron 100 | S32760 / J93380 | Super Duplex | P-10H Group 1 |
| DP-3 | S31260 | Duplex DP-3 | P-10H Group 1 |
| Ferralium 255 | S32550 | Super Duplex | P-10H Group 1 |
| Cast Super Duplex | ASTM A890 | Pump/Valve Castings | P-10H |
Dissimilar Metal Joints:
| Joint Combination | Application |
|---|---|
| Super Duplex to Carbon Steel (P-1) | Transition joints, flange-to-pipe |
| Super Duplex to Duplex 2205 (P-10H) | Mixed-grade piping systems |
| Super Duplex to 316L Austenitic (P-8) | Process equipment tie-ins |
| Root runs on UNS S32205 & J92250 | When PREN ≥40 is specified for root |
ASME IX: F-5, A-8. When connecting UNS S32550, J93370, or J03372, consult a corrosion engineer before using E2594-16 in sulphurous or sulfuric acid service. PREN ≥35 is adequate for conventional duplex 2205 joints, making E2209-16 more cost-effective.
Welding Parameters & Procedure Guidance for E2594-16
Standard duplex welding requires looser parameter control than super duplex. To avoid excessive ferrite and harmful intermetallic phases, heat input must be balanced.
| Diameter (mm/in) | Flat (A) | V/OH (A) | Voltage (V) | Polarity |
|---|---|---|---|---|
| 2.4 mm (3/32″) | 65-90 | 60-80 | 24-28 | DCEP or AC |
| 3.2 mm (1/8″) | 80-115 | 75-95 | 26-30 | DCEP or AC |
| 4.0 mm (5/32″) | 110-150 | 100-125 | 27-32 | DCEP or AC |
Welding requires no preheat, but interpass temperatures must not exceed 150°C. Use stringer beads with widths under 2.5× electrode diameter to maintain heat input between 0.5 and 2.5 kJ/mm. Reduce the amperage by 10-20% for out-of-position work. Don’t do PWHT to stop sigma phase embrittlement; if it’s necessary, heat treat at 1050-1120°C and then cool quickly in water.
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Critical-Service Welding Applications of E2594-16 Welding Rod
The following are the primary applications of E2594-16 Welding Rod in various industries
E2209-16 duplex electrodes provide vital welding performance where high strength and corrosion resistance are simultaneously required.
- We supply E2594-16 for super duplex manifolds, Christmas tree components, and flowline tie-ins in subsea sour gas wells exceeding 1,000-metre depths.
- E2594-16 welds facilitate 2507 RO membrane housings and seawater intake pipes, providing critical pitting resistance for saltwater desalination evaporators and condensers up to 80°C.
- E2594-16 is commonly specified for chloride reactors, shafts, scrubbers, and phosphoric acid equipment; E2209 electrodes can induce premature pitting in super duplex welding applications.
- E2594-16 is mandatory for 2507 firewater systems, riser clamps, and splash zone brackets, requiring DNV, ABS, Lloyd’s Register, or BV class approvals.
- This electrode is used to weld super duplex pipes that deal with slurries in tough conditions and pipes in acid leach plants that carry sulphuric/hydrochloric acid and chloride ions.
Storage, Handling & Moisture Control for E2594-16 Electrodes
Super duplex E2594-16 coated electrodes are a premium consumable. Proper storage and handling maximise weld quality and minimise costly waste.
Seal the cans at 15 to 25°C with relative humidity less than 50%. The oven holds the opened cans at 100 to 150°C. Re-bake rutile at 300 to 350°C for 2 hours according to the E2594-16 procedure, or the simple procedure of E2594-15 at 370 to 400°C for 1 hour, a maximum of twice. Avoid exposure for 4 hours, or 2 hours under humid conditions.
Nicorex Alloys supplies hermetically sealed metal cans (2.5 kg, 5.0 kg) and vacuum-sealed cartons. Individual labels include AWS classifications, batch numbers, diameters, and heat numbers.
How to Order E2594-16 Super Duplex Electrode from Nicorex Alloys
To request a quotation for E2594-16 super duplex stainless steel electrodes, iprovide following details:
- AWS Classification - E2594-16 rutile or E2594-15 basic
- Diameter(s) Required - Diameter(s) required
- Quantity - Quantity in kg
- Required Approvals - DNV, ABS, BV, LR, TUV
- ASTM G48 / Ferrite Requirements - ASTM G48 or ferrite measurement requirements
- Packaging Preference - Hermetic can, vacuum-sealed
- Test Certificate Scope - Standard MTC 3.1 or extended with PREN/G48
- Delivery Destination - Delivery destination
Super duplex stick electrodes are specialist items; buy early for manufacturer clearance. Standard stock takes 3-7 business days; special manufacturer/approval combinations take 2-4 weeks.
Frequently Asked Questions
What is the Price of E2594-16 Super Duplex Electrode per Kg in India?
Diameter, order volume, coating type (-16 rutile vs. -15 basic), and third-party approvals (DNV, ABS) are all variables in the cost of E2594-16. Super duplex electrodes are more costly than E2209-16 owing to the alloy content. Nicorex Alloys is the source of competitive batch-tested stock based in Mumbai. Report your price needs.
Can E2594-16 Electrode be Used for Welding Standard Duplex 2205?
E2594-16 rivals duplex 2205 joints. However, it costs substantially more than E2209-16. Use E2594-16 on 2205 only when PREN ≥40 weld deposit is needed or when root passes on duplex 2205 meet super duplex corrosion standards. For standard 2205 fabrication, E2209-16 is best and cheapest.
What is the Ferrite Number Range for E2594-16 Weld Deposit?
FN 35-50 is typical as-welded ferrite. NORSOK M-601 and most project standards recommend FN 35-65 for corrosion resistance and toughness. AWS A4.2 measures ferrite magnetically or chemically using the WRC-1992 diagram. Every Nicorex Alloys MTC 3.1 measures ferrite.
What is the Typical Lead Time for E2594-16 Super Duplex Electrodes?
Nicorex Alloys ships its normal stock from Mumbai in 3-7 days. Specific manufacturer or permission requirements (e.g., DNV GL certificates from listed manufacturers) take 2-4 weeks. Super duplex consumables are a speciality with a few manufacturers; project-critical volumes should be ordered early.
What is the Difference Between E2594-16 and E2209-16 Duplex Electrodes?
E2594-16 super duplex deposits 25Cr-10Ni-4Mo-0.25N at ≥40 PREN and 760 MPa UTS. For UNS S32750, S32760, and Ferralium 255, E2209-16 deposits 22Cr-9Ni-3Mo-0.17N with PREN ≥35 and UTS min 690 MPa for S31803/S32205 and S32304. E2594 shows ~20% more PREN, double Mo (4% vs 3%), and higher N (0.25% vs 0.17%). Match electrode PREN to base metal PREN.
When Not to Use E2594-16 Super Duplex Electrode?
E2594-16 should not be used in 5 situations:
- Do not use for standard duplex 2205 (S31803/S32205) when the service PREN requirement is ≤35. E2209-16 is sufficient and significantly more cost-effective.
- Do not use for austenitic stainless joints (304, 316L). The high ferrite content (~45-55 FN) is incompatible with fully austenitic base metals. Use E308L-16 or E316L-16.
- Do not use UNS S32550, J93370, or J03372 in sulphurous or sulphuric acid service. This application is explicitly excluded in published manufacturer datasheets.
- Avoid 300°C continuous use. Rapid sigma-chi phase formation weakens toughness and corrosion resistance. High-temperature consumables should be austenitic (E347-16) or nickel alloy.
- Do not use without strict heat input control (0.5-2.5 kJ/mm). Shops that cannot monitor welding parameters will produce out-of-spec ferrite content.