AWS Class E9015-B9 / E9018-B9 Welding Electrodes
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AWS Class E9015-B9 / E9018-B9 Welding Electrodes Supplier in Mumbai, India
Nicorex Alloys is an ISO 9001 / ISO 14001 certified supplier and stockist of E9018-B9 welding electrodes, based in Mumbai, India. We provide these electrodes classified under AWS A5.5 / ASME SFA 5.5.
E9018-B9 (also known as E9018-B91) is a special, low‑hydrogen welding rod with a basic coating, used for stick welding (SMAW) of strong, high‑temperature 9Cr‑1Mo‑V‑Nb steels. Its weld deposit contains 8.0-10.0% Cr, 0.85-1.20% Mo, with critical additions of 0.15-0.25% V, 0.03-0.07% Nb, and 0.02-0.07% N. These elements form MX-type (V, Nb)(C, N) carbonitride precipitates during PWHT, the sole mechanism behind Grade 91 creep rupture strength. After postweld heat treatment (PWHT) at 760°C for 2 hours, the weld metal typically achieves an ultimate tensile strength (UTS) of at least 620 MPa (90 ksi), a minimum elongation of 17%, and a Charpy V‑Notch impact energy (CVN) of at least 27 J at +20°C. A similar electrode, E9015-B9, has a sodium-based coating and operates only on DCEP. It produces essentially the same weld metal chemistry as E9018-B9 but is often chosen for critical pipe welding because it usually contains lower levels of residual (trace) elements.
Available diameters are 2.5, 3.15, 4.0, and 5.0 mm in lengths of 350-450 mm, packed in hermetically sealed cans (2.5 kg, 5.0 kg). Polarity is DCEP or AC; E9015-B9 operates on DCEP only. Base metals fall under ASME P-No. 15E Group 1: A335 P91, A213 T91, A182 F91, A387 Gr.91, A217 C12A, and A234 WP91. Industries served by these electrodes include power generation, petrochemical processing, HRSG systems, and nuclear applications.
E9018-B9 Electrode Specifications & Technical Data
The specifications of E9018-B9, along with its AWS classification, polarity and diameters, are mentioned in the table below:
| AWS Classification | E9018-B9 (also E9018-B91) E9015-B9 (also E9015-B91) |
|---|---|
| Specification | AWS A5.5 / ASME SFA 5.5 |
| Coating Type | Low-hydrogen, potassium silicate + iron powder E9015-B9: Sodium silicate — no iron powder |
| Current / Polarity | E9018-B9: DCEP or AC E9015-B9: DCEP only |
| Welding Positions | All positions (F, V-up, OH, H) |
| Diameters | 2.5, 3.15, 4.0, 5.0 mm |
| Deposition Efficiency | E9018-B9: ~110-120% E9015-B9: ~95-105% |
E9015-B9 is preferred for critical P91 piping because lower iron powder keeps the X-Factor below 15. E9018-B9 suits fill/cap passes where productivity and AC capability matter.
Understanding the AWS E9018-B9 / E9015-B9 Electrode Designation
The table below explains the designation of the E9018-B9/ E9015-B9 electrode with its meaning:
| Designaton | Meaning |
|---|---|
| E | Electrode for SMAW (stick welding) |
| 90 | Minimum tensile strength: 90,000 psi (620 MPa) |
| 1 | All-position welding capability |
| 5 | Low-hydrogen sodium coating |
| 8 | Low-hydrogen potassium silicate + iron powder coating — DCEP and AC |
| B9 | 9Cr-1Mo modified with V + Nb + N (9Cr-1Mo-V-Nb) |
AWS introduced “B91” to prevent confusion with “B8” (standard 9Cr-1Mo without V, Nb, or N). Both designations remain valid. Using E8018-B8 on P91 steel is a critical procurement error that produces a joint lacking creep-strength precipitates.
Chemical Composition of E9018-B9 / E9015-B9 Weld Deposit (%)
The chemical composition of the E9018-B9 weld deposit, along with its proportion in percentage, is listed below in the table:
| Material / Element | Carbon (C) | Manganese (Mn) | Silicon (Si) | Chromium (Cr) | Molybdenum (Mo) | Vanadium (V) | Niobium (Nb) | Nickel (Ni) | Nitrogen (N) | Phosphorus (P) | Sulphur (S) | Copper (Cu) | Aluminium (Al) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| AWS A5.5 Range | 0.08-0.12% | 0.40-0.75% | 0.30% max | 8.00-10.00% | 0.85-1.20% | 0.15-0.25% | 0.03-0.07% | 0.20-0.40% | 0.02-0.07% | 0.010% max | 0.010% max | 0.25% max | 0.04% max |
V, Nb, and N form MX-type nano-precipitates during PWHT at 760°C, providing creep rupture strength up to 600°C for 100,000+ hour design lifetimes. P and S limits are 3× stricter than B8 due to CSEF temper embrittlement susceptibility.
Mechanical Properties of E9018-B9 / E9015-B9 All-Weld-Metal
The mechanical properties of E9018-B9/ E9015-B9, including tensile strength, hardness and elongation, are mentioned in the table below:
| Property | UTS | YS (0.2%) | Elongation | Hardness |
|---|---|---|---|---|
| AWS A5.5 Min. | ≥620 MPa (90 ksi) | Not specified | ≥17% | Per code |
| As-Welded (Typical) | 758 MPa (110 ksi) | 690 MPa (100 ksi) | 18% | >400 HV |
| After PWHT (Typical) | 620-690 MPa | 520-580 MPa | 20-24% | ≤275 HV |
PWHT is mandatory at 730-770°C (typically 760°C) for a minimum of 2 hours. PWHT must never exceed Ac1 (~800-810°C); exceeding Ac1 destroys the MX precipitate structure irreversibly.
Base Metal Compatibility & P-Number Matrix for E9018-B9
The table below shows the base metal, its compatibility, and the corresponding grade and ASME number:
| Base Metal | Grade | ASME P-No. | Notes |
|---|---|---|---|
| 9Cr-1Mo-V Steel | A335 P91 | P-15E Gr.1 | Seamless pipe |
| 9Cr-1Mo-V Steel | A213 T91 | P-15E Gr.1 | Boiler/superheater tube |
| 9Cr-1Mo-V Steel | A182 F91 | P-15E Gr.1 | Forged fittings and flanges |
| 9Cr-1Mo-V Steel | A387 Gr.91 Cl.2 | P-15E Gr.1 | Pressure vessel plate |
| 9Cr-1Mo-V Steel | A217 C12A | P-15E Gr.1 | Castings |
| 9Cr-1Mo-V Steel | A234 WP91 / A369 FP91 / A336 F91 | P-15E Gr.1 | Fittings and heavy forgings |
P-15E Gr.1 materials are upgraded 9Cr-1Mo steels designed to work safely at high temperatures for long periods. They are widely used in power plants and refineries because they are strong, resist rust and oxidation, and remain stable over long service times at elevated temperatures.
Recommended Welding Parameters for AWS Class E9015-B9
The following table lists recommended welding parameters for AWS Class E9015-B9 electrodes, including diameter, current range, and compatibility details:
| Dia. (mm) | Length (mm) | Current (A) | AC | E9015-B9 (A) |
|---|---|---|---|---|
| 2.5 | 350 | 60-90 | Yes | 70-110 |
| 3.15 | 350 | 80-130 | Yes | 80-140 |
| 4.0 | 350/450 | 130-170 | Yes | 100-180 |
| 5.0 | 450 | 170-230 | Yes | 140-240 |
Preheat joints to 200-300°C, using 250-300°C for sections thicker than 25 mm, and keep interpass temperatures under 300°C. After welding, cool to 80-100°C for 1 hour before PWHT at 730-770°C for 2 hours per 25 mm. Final hardness must not exceed 275 HV.
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Industrial Welding Applications of E9018-B9 Coated Electrode
E9018-B9 coated electrode is used to withstand tough operating conditions in these high-performing industries:
- Power Generation: Main steam piping (A335 P91), headers, superheater tube welding (A213 T91) and header fabrication.
- Petrochemical Processing: Ethylene cracker outlet headers, FCCU regenerator piping, and hydrocracker effluent systems.
- HRSG & Combined Cycle: Used in HP superheater sections in combined-cycle plants and header-to-tube socket welds.
- Nuclear & Advanced Energy: P91 structural components for Generation IV reactor concepts and concentrated solar power receiver tubing.
Storage, Handling & Re-Drying Procedures for E9018-B9
Keep electrodes in factory-sealed containers until use. After opening, transfer to a holding oven at 120-175°C. If exposed >1 hour, re-bake at 300-400°C for 1 hour. Maximum 2 re-baking cycles; discard after. Issue in heated quivers; 2-hour exposure limit. Keep diffusible hydrogen at 4 ml or less per 100 g of weld metal (H4).
How to Order E9018-B9, E9015-B9 Electrodes from Nicorex Alloys
To order the E9018-B9/ E9015-B9 electrode from Nicorex Alloys, provide these 10 important details:
- Electrode Type: SMAW AWS A5.5 E9018-B9 / E9015-B9
- Size: 2.5mm, 3.2mm, 4.0mm electrodes
- Current Type: DCEP
- Welding Position: All except vertical down
- Material Grade: P91 / UNS W50411 / E9018-B9 / 1.4903 / ISO 3580-A
- Quantity: 5kg cans / 20kg cartons
- Standard: AWS A5.5 / ASME SFA 5.5 / ISO 3580
- Documentation: MTC EN 10204 3.1, TPI report
- Packaging: Hermetically sealed can
- Delivery Destination: Domestic
Frequently Asked Questions
What is the difference between E9018-B9 and E9015-B9 Welding Electrodes?
Both deposit identical 9Cr-1Mo-V-Nb weld metal. E9015-B9 uses sodium silicate (DCEP only, ~95-105% efficiency, lower tramp elements); E9018-B9 uses potassium silicate with iron powder (DCEP/AC, ~110-120%). E9015-B9 is preferred for critical P91 work due to the lower X-Factor.
Can E8018-B8 be used to weld P91 (9Cr-1Mo-V-Nb) Steel?
No. E8018-B8 deposits standard 9Cr-1Mo without V, Nb, or N. The weld joint lacks MX precipitates, with creep strength 50-70% below P91 base metal at 600°C. Every P91 WPS must specify B9 (or B91) consumables.
Why is E9015-B9 generally preferred over E9018-B9 for P91 Pipe Welding?
Lower iron powder in E9015-B9 yields deposits with reduced P, Sn, Sb, and As, keeping the X-Factor below 15 for temper embrittlement resistance over 100,000+ hours at 550-600°C. Most EPRI-aligned specifications mandate E9015-B9.
What PWHT is required for E9018-B9 Weld Deposits on P91?
730-770°C (typically 760°C) for a minimum of 2 hours per 25 mm thickness. Never exceed Ac1 (~800-810°C); exceeding Ac1 destroys the MX precipitate structure irreversibly. Post-PWHT hardness: ≤275 HV (≤253 HB).
When should you not use E9018-B9 Welding Electrode?
Do not use E9018-B9 welding electrode on standard 9Cr-1Mo (P9/T9), use E8018-B8. Do not use on P92 or P122; use E9015-B92. Do not apply PWHT above 800°C (Ac1). Do not use for root passes; use ER90S-B9 GTAW. Always cool to 80-100°C for martensite transformation before PWHT.