UltraCore® 712C is Lincoln Electric's mild-steel, all-position gas-shielded flux-cored (FCAW-G) wire classified AWS A5.20 / A5.20M E71T-12C-JH8 and, under the combined specification, AWS A5.36 E71T1-C1A4-CS2-H8. It is designed for welding with 100% CO₂ and is capable of producing weld deposits with impact toughness exceeding 27 J (20 ft·lbf) at −40 °C (−40 °F). The reason it appears on bridge, pressure vessel, and ASME-related procedures rather than general fabrication work is the E71T-12 classification itself: it carries a capped tensile range and controlled manganese, which is what code work needs from a 70 ksi flux-cored wire. WeldingMart is an authorized Lincoln Electric distributor; every spool ships factory-sealed in Lincoln packaging.
This page is the family hub for the UltraCore 712C line. Lincoln publishes it in 0.045 in (1.1 mm), 0.052 in (1.3 mm), and 1/16 in (1.6 mm) across 15 lb plastic spools, 60 lb master cartons, 33 lb spools, 50 lb fiber spools, and the 500 lb Accu-Trak® drum, with Buy America part numbers available in several of those formats. The formats stocked here are listed at the bottom of this page. Browse the wider range in the Welding Wire collection.
| AWS Classification | AWS A5.20 / A5.20M E71T-12C-JH8 (also classified E71T-1C-JH8 and E71T-9C-JH8) |
|---|---|
| AWS A5.36 Classification | E71T1-C1A4-CS2-H8 |
| Wire Type | Mild steel, gas-shielded flux-cored (FCAW-G) |
| Welding Positions | All |
| Shielding Gas | 100% CO₂; flow rate 40–50 CFH |
| Polarity | DC+ (DCEP — DC Electrode Positive) |
| Impact Toughness | Capable of exceeding 27 J (20 ft·lbf) at −40 °C (−40 °F) |
| Diffusible Hydrogen | H8 (8 mL/100 g maximum); 3–8 mL/100 g typical |
| Available Diameters | 0.045 in (1.1 mm), 0.052 in (1.3 mm), 1/16 in (1.6 mm) |
| Package Formats | 15 lb (6.8 kg) plastic spool; 60 lb (27.2 kg) master carton; 33 lb (15 kg) spool (plastic or fiber); 50 lb (22.7 kg) fiber spool; 500 lb (227 kg) Accu-Trak® drum |
| Domestic Preference Options | Buy America part numbers published in several diameter/package combinations |
| Packaging Protection | ProTech® foil bag packaging |
| Brand / Manufacturer | Lincoln Electric |
Source: Lincoln Electric UltraCore 712C datasheet (Publication C3.12.9), supported by the Lincoln FCAW-G classification guide for 71T-1, -9 and -12 wires.
- Toughness at −40 °C: Capable of producing weld deposits with impact toughness exceeding 27 J (20 ft·lbf) at −40 °C (−40 °F), with published typical Charpy values well above that figure.
- Single-gas simplicity: Designed for 100% CO₂ — no mixed-gas inventory required.
- Premium arc performance and bead appearance: Lincoln lists both as key features. On visible structural and bridge work, bead appearance is not cosmetic — it is what the inspector looks at first.
- Triple classification: Classified E71T-1C-JH8, E71T-9C-JH8, and E71T-12C-JH8, which gives procedure writers latitude to reference whichever classification their code recognises.
- Broad classification-society approval: ABS, Lloyd's Register, DNV, and CWB approvals in addition to AWS and ASME (full list below).
- Tolerant of imperfect surfaces: Lincoln's classification guide for this wire family notes the ability to weld over light rust, mill scale, and primer — a real advantage on bridge and structural steel that has been sitting outside.
- ProTech® foil bag packaging: Moisture barrier protecting the H8 hydrogen rating in storage.
- Bridge fabrication: Lincoln's first-listed application. Bridge codes are where the E71T-12 capped tensile range and controlled chemistry pay off.
- Pressure vessels: Lincoln's classification guide notes that E71T-12 meets ASME Section IX A-1 group manganese limits, which is what allows a flux-cored wire into pressure work at all.
- Shipbuilding: ABS 3YSA H10, Lloyd's 3YS H10, and DNV III YMS H10 approvals support classification-society hull and structural welding.
- Offshore fabrication: All-position high-deposition welding with certified low-temperature impact performance.
- ASME-related applications: Named directly by Lincoln as a typical application area.
- Heavy equipment and general structural steel: The classification guide lists heavy equipment manufacturers among the typical users of this wire family alongside bridge, offshore, and pressure vessel fabricators.
UltraCore 712C runs DC+ (DCEP) with 100% CO₂ at 40–50 CFH. It is gas-shielded and will not produce sound weld metal run open-arc.
All the published typical results below were established with 100% CO₂. Because the classification carries the "C" gas designator, substituting an argon mix is a procedure change, not a settings change. On outdoor bridge and structural sites, CO₂ shielding is more sensitive to wind than argon mixes at equal flow — screen the joint rather than simply increasing flow, because over-flowing the nozzle induces turbulence and pulls air into the shielding stream.
| Requirement — yield strength | 400 MPa (58 ksi) minimum |
|---|---|
| Requirement — tensile strength, E71T-1C-JH8 / E71T-9C-JH8 | 480–655 MPa (70–95 ksi) |
| Requirement — tensile strength, E71T-12C-JH8 | 480–620 MPa (70–90 ksi) — the narrower capped range |
| Requirement — elongation | 22% minimum |
| Requirement — Charpy V-notch | 27 J (20 ft·lbf) minimum |
| Typical as-welded (100% CO₂) — yield | 485–535 MPa (70–77 ksi) |
| Typical as-welded — tensile | 540–585 MPa (78–84 ksi) |
| Typical as-welded — elongation | 25–28% |
| Typical as-welded — CVN at −18 °C (0 °F) | 135–193 J (100–143 ft·lbf) |
| Typical as-welded — CVN at −29 °C (−20 °F) | 91–164 J (67–121 ft·lbf) |
| Typical as-welded — CVN at −40 °C (−40 °F) | 57–133 J (42–98 ft·lbf) |
Typical values are Lincoln Electric published all-weld-metal test results, not lot guarantees. The capped 480–620 MPa (70–90 ksi) tensile range of the E71T-12 classification is the technical reason this wire is used on code work: it constrains over-strength weld metal, which matters for weld-to-base-metal compatibility in pressure and bridge applications.
| Carbon (C) | 0.03% |
|---|---|
| Manganese (Mn) | 1.34–1.49% |
| Silicon (Si) | 0.26–0.32% |
| Nickel (Ni) | 0.33–0.41% |
| Diffusible hydrogen | 3–8 mL/100 g |
The controlled manganese level is the point of interest for code users: Lincoln's classification guide notes that E71T-12 wires meet the ASME Section IX A-1 group manganese limits, which E71T-1 wires at the top of their range may not.
- AWS A5.20 / A5.20M: E71T-1C-JH8, E71T-9C-JH8, E71T-12C-JH8
- AWS A5.36 / A5.36M: E71T1-C1A4-CS2-H8
- ASME SFA-A5.20
- ABS: 3YSA H10
- Lloyd's Register: 3YS H10
- DNV: III YMS H10
- CWB (Canadian Welding Bureau): E491T-12J H8, E491T-9J H8
- EN ISO 17632-B: T494T12-1CA-K-H10
Approvals can be diameter- and package-specific, and Buy America status applies only to designated part numbers. Verify the exact part number against the project's approved consumable list before ordering.
| 0.045 in (1.1 mm) | The most controllable diameter out of position and the choice where heat input is capped or sections are thinner. Published across the 15 lb plastic spool, 33 lb spool, 50 lb fiber spool, and 500 lb Accu-Trak® drum formats. |
|---|---|
| 0.052 in (1.3 mm) | The general-purpose production diameter, published at 85–88% deposition efficiency on 100% CO₂. Stocked here as the 33 lb spool, part number ED031673. |
| 1/16 in (1.6 mm) | Highest deposition of the three; requires a feeder, liner, and gun rated for 1/16 in cored wire and is normally run flat and horizontal on heavy plate. Stocked here as the 50 lb spool, part number ED034421. |
Format notes. The 15 lb plastic spool suits portable and light industrial feeders; 33 lb and 50 lb spools are the standard shop formats; the 500 lb Accu-Trak® drum is a bulk format for high-duty-cycle and automated cells and requires the matching payoff and conduit hardware. Lincoln notes that the 33 lb spool may be supplied as plastic or fiber.
- What does E71T-12C-JH8 mean?
- Under AWS A5.20: "E" electrode, "7" 70 ksi tensile class, "1" all positions, "T-12" a tubular wire meeting the T-12 requirements — the same rutile flux family as T-1 but with a capped tensile range and tighter chemistry — "C" 100% CO₂ shielding, "J" improved impact toughness at a lower test temperature, and "H8" diffusible hydrogen not exceeding 8 mL per 100 g of deposited metal.
- Why choose E71T-12 over E71T-1?
- The tensile cap and the chemistry. E71T-1 permits 480–655 MPa (70–95 ksi) tensile; E71T-12 narrows that to 480–620 MPa (70–90 ksi), and Lincoln's classification guide notes E71T-12 meets ASME Section IX A-1 group manganese limits. On pressure vessel and bridge work, over-strength weld metal and uncontrolled manganese are both problems, which is why code procedures reach for T-12.
- What shielding gas and flow?
- 100% CO₂ at 40–50 CFH, DC+ polarity. Do not substitute an argon mix without requalifying — the classification and all published data are tied to CO₂.
- Can it be welded over mill scale or primer?
- Lincoln's classification guide for the 71T-1/-9/-12 family notes the ability to weld over light rust, mill scale, and primer. That is a tolerance, not a licence: heavy scale, thick primer, oil, or moisture will still cause porosity and should be removed.
- What impact values can I expect at −40 °F?
- The classification requirement is 27 J (20 ft·lbf) minimum. Lincoln's published typical results as-welded with 100% CO₂ are 57–133 J (42–98 ft·lbf) at −40 °C (−40 °F), 91–164 J at −29 °C, and 135–193 J at −18 °C.
- Is a Buy America version available?
- Lincoln publishes Buy America part numbers for several diameter and package combinations of this wire. Because the designation is part-number specific, confirm the exact part number against the project requirement rather than assuming the product line qualifies.
- How is 712C different from the UltraCore 80 ksi wires?
- 712C is a mild-steel 70 ksi class wire. UltraCore 81K2C-H Plus and 81Ni1C-H Plus are low-alloy 80 ksi class wires with nickel additions and H4 hydrogen ratings, designed for −60 °F toughness. Different strength class, different alloy content, different hydrogen band — they are not substitutes for one another.
The formats stocked here have their own listings: 0.052 in, 33 lb spool (ED031673) | 1/16 in, 50 lb spool (ED034421) | All Welding Wire
— signed: SEO Silo-chat