AWS Class ER312 MIG & TIG
ER312 Welding Wire Importer in Mumbai, India
Nicorex Alloys is an ISO 9001 and ISO 14001 certified Mumbai-based supplier and stockist of ER312 welding wire. We provide these wires classified under AWS A5.9 / ASME SFA-5.9 with the EN ISO 14343-A.
ER312 is a high-chromium, moderate-nickel austenitic-ferritic (duplex) stainless steel solid wire with 28-32% Cr and 8-10.5% Ni. The weld deposit solidifies with roughly 25-40% ferrite in an austenite matrix, giving ER312 the best resistance to solidification cracking of any standard AWS A5.9 filler metal. Tensile strength reaches 724 MPa (105 ksi) in the as-deposited condition, the highest of any standard stainless steel filler wire. ER312, also called W 29 9 (G 29 9), was first made for welding 29Cr-9Ni cast alloys. Today, it’s mainly used as a reliable filler metal for steels that crack easily or have an unknown composition. When other fillers crack, ER312 usually does not.
Available as TIG rods in 1.6, 2.4, 3.2 mm and MIG spools in 0.8, 0.9, 1.2, 1.6 mm. Welding processes cover GTAW (DCEN, 100% Argon), GMAW (DCEP, Ar+2%O₂), and SAW. The maximum service temperature is 420°C (800°F); above this, the high-ferrite deposit transforms to sigma phase, causing severe embrittlement. Compatible base metals include 29Cr-9Ni castings, dissimilar joints (carbon steel to stainless steel), tool steels (D2, H13, S7), armour plate, manganese steels, and steels of unknown composition. Nicorex Alloys ships every lot with MTC 3.1 per EN 10204.
ER312 Welding Wire Specifications
ER312 welding wire specifications, including welding process, shielding gas, diameter and lengths are listed in the table below:
| Welding Processes | GTAW (TIG), GMAW (MIG), SAW |
|---|---|
| Polarity – GTAW / GMAW | DCEN / DCEP |
| Welding Positions | All positions |
| Shielding Gas – | GTAW: 100% Argon GMAW: Ar+2%O₂ |
| TIG Rod Diameters | 1.6, 2.4, 3.2 mm |
| MIG Wire Diameters | 0.8, 0.9, 1.2, 1.6 mm |
| TIG Rod Length | 1000 mm (36″) |
| Spool Sizes | D200 (12.5 kg), D300 (15 kg) |
AWS Classification Explained: What Does ER312 Mean?
The table below explains the meaning of common welding filler metal designators and the alloy characteristics associated with each classification.
| Designator | Meaning |
|---|---|
| ER | Stands for Electrode/Rod, indicating a bare solid welding wire used in processes such as GTAW or GMAW. |
| 312 | Refers to the alloy composition type: approximately 29% Chromium and 9% Nickel. The weld deposit forms a duplex microstructure with about 25–40% ferrite, giving excellent crack resistance. |
Chemical Composition of ER312 Weld Deposit (%)
The weld deposit chemistry of ER312, along with typical deposited values, is mentioned in the table below.
| Property | Carbon (C) | Chromium (Cr) | Nickel (Ni) | Molybdenum (Mo) | Manganese (Mn) | Silicon (Si) | Phosphorus (P) | Sulphur (S) | Copper (Cu) |
|---|---|---|---|---|---|---|---|---|---|
| AWS A5.9 | 0.15% max | 28.0–32.0% | 8.0–10.5% | 0.75% max | 1.0–2.5% | 0.30–0.65% | 0.03% max | 0.03% max | 0.75% max |
| Typical | 0.11% | 29.00% | 9.25% | 0.15% | 1.60% | 0.40% | 0.013% | 0.013% | – |
Cr at 28-32% with Ni at 8-10.5% yields 25-40% delta ferrite in the weld metal. Carbon up to 0.15% is permitted because ER312 is selected for crack resistance, not aqueous corrosion service.
All-Weld-Metal Mechanical Properties of ER312
Mechanical properties of ER312, along with tensile strength, elongation and yield strength, are listed in the table below:
| Property | Tensile Strength | Yield Strength (0.2%) | Elongation | Reduction of Area |
|---|---|---|---|---|
| WeldWire (MIG, Ar+2%O₂) | 724 MPa (105,000 psi) | 517 MPa (75,000 psi) | 25% | 30% |
| MFG Shop | 755 MPa (109,500 psi) | 541 MPa (78,500 psi) | 25–45% | – |
Base Metal Compatibility and “Problem Steel” Applications for ER312
The base metal and its compatibility, along with the grade and ASME number, are listed in the table below:
| Base Metal | Grade | ASME No. | Notes |
|---|---|---|---|
| Cast alloys | 29Cr-9Ni | P-8 (approx.) | Limit to 2–3 layers |
| Carbon steel to stainless steel | P-1 to P-8 | F-5, A-No. 10 | Resists fusion-line cracking |
| Nickel alloys to stainless steel | P-43 to P-8 | F-5, A-No. 10 | Handles dilution from both sides |
| High-carbon steels | >0.30% C | P-1 / P-3 | Reduces solidification cracking |
| Tool steels | D2, H13, S7, A2 | P-5 / P-6 | Crack-resistant HAZ |
| Spring steels | High C-Mn | P-1 / P-3 | Tolerates high dilution |
| Armour / ballistic plate | Hardened steel | P-1 | Crack-resistant joining |
| Manganese steels | Hadfield | P-1 | Handles Mn dilution |
| Unknown steels | Unidentified | — | Safe general-purpose filler |
ER312 is preferred for crack-sensitive and dissimilar welding rather than matching compositions. It is unsuitable for corrosion-critical environments; 316L or nickel fillers are better. Service temperature should remain below 420°C to prevent sigma phase embrittlement and loss of toughness.
Recommended Welding Parameters for ER312 TIG & MIG Wire
Below are practical ER312 TIG and MIG welding parameters to help you select safe, reliable settings:
GMAW Parameters (Ar+2%O₂, DCEP)
| Transfer | Diameter | Amps | Volts | Gas Flow |
|---|---|---|---|---|
| Short Arc | 0.8 mm (0.030″) | 40–120 | 16–20 | 25 CFH |
| Short Arc | 0.9 mm (0.035″) | 60–140 | 16–22 | 25 CFH |
| Spray Arc | 0.9 mm (0.035″) | 140–220 | 24–29 | 38 CFH |
| Spray Arc | 1.2 mm (0.045″) | 160–260 | 25–30 | 38 CFH |
| Spray Arc | 1.6 mm (1/16″) | 230–350 | 27–31 | 38 CFH |
GTAW Parameters (100% Argon, DCEN)
| Diameter | Amps | Volts |
|---|---|---|
| 1.6 mm (1/16″) | 80–130 | 12–16 |
| 2.4 mm (3/32″) | 120–175 | 14–18 |
| 3.2 mm (1/8″) | 150–220 | 15–20 |
Preheat is not required for stainless base metals. For tool steels, preheat to 150-260°C (300-500°F). Use short beads, peen between passes, and allow slow cooling.
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Industrial Welding Applications of ER312 Filler Wire
ER312 filler wire is used in demanding industrial welding jobs where high crack resistance, mixed metals, and tough repair conditions occur:
- Maintenance and repair work: Used as a universal repair filler for mixed-metal and unknown steel grades.
- Tool and die industry: Ideal for repairing D2, H13, S7, and A2 tool steels.
- Dissimilar metal fabrication: Joins carbon steel to stainless steel, nickel alloys to stainless steel, and ferritic to austenitic stainless steels.
- 29Cr-9Ni cast alloy repair: Serves as the original matching filler for repairing 29Cr‑9Ni and similar heat‑resistant casting grades.
- Spring steel repair: Used to weld and rebuild valve springs, suspension parts, and agricultural springs.
- Railway maintenance: Applied for repairing rail crossings, switch points, and high‑manganese frog castings.
- Overlay and surfacing: Provides a crack‑resistant duplex overlay on carbon steel.
- Agricultural machinery: Repairs plough shares, cultivator points, and other hardened farm implements.
Storage and Handling of ER312 Welding Wire
Store sealed, clean, and dry at 15-30°C. Keep separated from carbon steel to prevent contamination. Clean TIG rods with acetone before use. Shelf life is indefinite in sealed packaging.
Available Forms, Diameters and Packaging of ER312 Filler Wire
ER312 welding wire is available in multiple forms, diameters, and packagings as listed below in the table:
| Form | Diameters | Packaging |
|---|---|---|
| TIG Rod | 1.6, 2.4, 3.2 mm | 5 kg tubes, 1000 mm lengths |
| MIG Spool | 0.8, 0.9, 1.2, 1.6 mm | D200 (12.5 kg), D300 (15 kg) |
| SAW Wire | 2.4, 3.2, 4.0 mm | 25 kg coils |
How to Order ER312 Welding Wire from Nicorex Alloys
To order ER312 welding wire, follow these 10 important details:
- Wire Type: GTAW / GMAW; AWS A5.9 / ASME SFA-5.9: ER312
- Size: GTAW: 1.6, 2.4, 3.2 mm cut lengths; GMAW: 0.9, 1.0, 1.2 mm spools
- Current Type: GTAW: DCEN; GMAW: DCEP, 100% Ar or Ar/CO₂ shielding gas
- Welding Position: All positions (1G, 2G, 3G, 4G, 6G)
- Material Grade: 312; UNS S31200; W.Nr. 1.4457; EN ISO 14343-A: W 29 9
- Quantity: GTAW: 5 kg packs; GMAW: 15 kg spools
- Standard: AWS A5.9 / ASME SFA-5.9; EN ISO 14343; ASME Section IX
- Documentation: MTC EN 10204 3.1/3.2; FN Report; TPI certificate
- Packaging: GTAW- rigid plastic tubes/cardboard box; GMAW- vacuum-sealed foil bag with silica gel; ISPM 15 export cartons
- Delivery Destination: Domestic
Frequently Asked Questions
What is the Price of ER312 stainless steel welding wire per kg in India?
Pricing of ER312 stainless steel welding wire depends on diameter, form, and order volume. Due to the high chromium content (28-32%), ER312 typically costs more than ER308L or ER309L per kg. Contact Nicorex Alloys for a current quotation.
Why is ER312 called a Problem Solver Filler Metal?
ER312 deposits a duplex weld metal with 25-40% ferrite, the highest of any standard stainless filler. This ferrite content arrests solidification cracking even on tool steels, spring steels, armour plate, and steels of unknown composition.
Can ER312 be used for welding tool steels like D2, H13, and S7?
Yes. ER312 is one of the most commonly specified fillers for tool steel repair. Preheat to 150-260°C (300-500°F), use short beads, peen between passes, and allow slow cooling. The weld will be softer than the base metal but will hold without cracking.
Why should ER312 welds be limited to 2-3 Layers on Similar Cast Alloys?
Each successive layer reheats previous passes. In deposits with 25-40% ferrite, repeated thermal cycling promotes sigma phase nucleation. Limiting to 2-3 layers keeps heat exposure within safe limits.
What are the F-Number and A-Number for ER312 Per ASME Section IX?
ER310 has 0.08-0.15% carbon; ER310H has 0.35-0.45%. Both share the same Cr/Ni balance. ER310H is for severe carburising service (pyrolysis tubes). ER310 covers general high-temperature oxidation.
When should ER312 not be used?
Do not use ER312 above 420°C (800°F) due to sigma phase embrittlement. Do not use it for corrosion-critical chemical service where 316L or nickel alloy fillers perform better. Avoid PWHT above 500°C, as it accelerates sigma phase.