UltraCore® 81K2C-H Plus is Lincoln Electric's low-alloy, all-positions gas-shielded flux-cored (FCAW-G) wire classified AWS A5.29 E81T1-K2C-JH4 and, under the combined specification, AWS A5.36 E81T1-C1A6-K2-H4 and E81T1-C1P4-K2-H4. It is built around one hard requirement: producing weld metal with superior toughness at −60 °F (−51 °C) both as-welded and after stress relief, while holding an H4 diffusible hydrogen level. That combination is why it appears on offshore, low-temperature storage tank, and shipbuilding procedures. WeldingMart is an authorized Lincoln Electric distributor; every spool ships in its original factory-sealed Lincoln packaging.
This page is the family hub for the 81K2C-H Plus line. Lincoln publishes it in 0.045 in (1.1 mm), 0.052 in (1.3 mm), and 1/16 in (1.6 mm) on the 33 lb (15 kg) spool — part numbers ED034864, ED034865, and ED034866 respectively. All three are stocked here as individual listings, linked at the bottom of this page. See the wider range in the Welding Wire collection.
| AWS Classification | AWS A5.29 E81T1-K2C-JH4 |
|---|---|
| AWS A5.36 Classification | E81T1-C1A6-K2-H4; E81T1-C1P4-K2-H4 |
| ASME | ASME SFA-5.29 |
| Wire Type | Low alloy, gas-shielded flux-cored (FCAW-G) |
| Welding Positions | All |
| Shielding Gas | 100% CO₂; flow rate 40–50 CFH |
| Polarity | DC+ (DCEP — DC Electrode Positive) |
| Diffusible Hydrogen | H4 (4 mL/100 g maximum); 2–4 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 | 33 lb (15 kg) spool, ProTech® foil bag packaging |
| Part Numbers | ED034864 (0.045 in), ED034865 (0.052 in), ED034866 (1/16 in) |
| Lot Documentation | Q2 Lot® — certificate showing actual deposit chemistry and mechanical properties per lot, available online |
| Brand / Manufacturer | Lincoln Electric |
Source: Lincoln Electric UltraCore 81K2C-H Plus product page and the published UltraCore 81K2C-H Plus datasheet.
- Toughness at −60 °F in both conditions: Lincoln states the wire is capable of superior toughness at −60 °F (−51 °C) as-welded and stress-relieved. Many low-alloy flux-cored wires meet one condition but lose impact values after PWHT; this one is qualified in both.
- H4 diffusible hydrogen: Typical measured hydrogen is 2–4 mL/100 g, keeping the deposit inside the H4 band that hydrogen-cracking-sensitive procedures demand.
- Single-gas simplicity: Designed for welding with 100% CO₂ — no mixed-gas inventory, and CO₂ is the cheapest shielding option on the shop floor.
- Q2 Lot® certification: Actual deposit chemistry and mechanical properties are published per lot and retrievable online, which is what auditors and class societies ask for.
- ProTech® foil bag packaging: Moisture-barrier packaging protects the hydrogen level of the wire between manufacture and the arc — the H4 rating means nothing if the spool has absorbed moisture in storage.
- All-position operability: Rutile T1 flux system, so vertical-up and overhead passes are practical rather than theoretical.
- Offshore drilling rigs: Named by Lincoln as a typical application. Offshore structural work combines low service temperature, heavy sections, and inspection regimes that will not tolerate hydrogen cracking.
- Low-temperature storage tanks: The −60 °F toughness requirement, in both as-welded and stress-relieved condition, is exactly the cryogenic-adjacent tank case.
- Shipbuilding: Hull and structural weldments where an all-position flux-cored wire with certified impact values is preferred to solid wire for deposition rate reasons.
- Construction and heavy structural steel: High-deposition all-position welding on plate where 80 ksi class strength is specified.
- Pressure and stress-relieved fabrication: Because Lincoln publishes stress-relieved properties (1 hour at 621 °C / 1150 °F), the wire can be used where PWHT is mandatory without guessing at post-PWHT toughness.
UltraCore 81K2C-H Plus runs on DC+ (DCEP) with 100% CO₂ at 40–50 CFH. This is a gas-shielded wire: it is not self-shielded and will not produce sound weld metal without gas coverage.
Two practical notes. First, the published properties in the tables below were established on 100% CO₂ — substituting an argon/CO₂ mix changes the deposit chemistry recovery and invalidates the published values for procedure purposes. Second, CO₂ is more sensitive to draught than argon mixes at the same flow; on windy structural sites, screen the joint rather than simply increasing flow, because excessive flow induces turbulence and aspirates air into the shielding stream.
| Requirement — yield strength | 470 MPa (68 ksi) minimum |
|---|---|
| Requirement — tensile strength | 550–690 MPa (80–100 ksi) |
| Requirement — elongation | 19% minimum |
| Requirement — Charpy V-notch | 27 J (20 ft·lbf) minimum |
| Typical as-welded — yield | 491–531 MPa (71–77 ksi) |
| Typical as-welded — tensile | 576–604 MPa (84–88 ksi) |
| Typical as-welded — elongation | 24–26% |
| Typical as-welded — CVN at −40 °C (−40 °F) | 107–117 J (79–86 ft·lbf) |
| Typical as-welded — CVN at −51 °C (−60 °F) | 119–135 J (88–100 ft·lbf) |
| Typical stress-relieved (1 hr at 621 °C / 1150 °F) — yield | 477–488 MPa (69–71 ksi) |
| Typical stress-relieved — tensile | 575–580 MPa (83–84 ksi) |
| Typical stress-relieved — elongation | 27% |
| Typical stress-relieved — CVN | 120–147 J (89–108 ft·lbf) |
Typical values are Lincoln Electric published test results and are not lot guarantees. For code work, pull the Q2 Lot® certificate for the specific spool.
| Carbon (C) | 0.05% |
|---|---|
| Manganese (Mn) | 1.39–1.56% |
| Silicon (Si) | 0.30–0.36% |
| Nickel (Ni) | 1.54–1.72% |
| Diffusible hydrogen | 2–4 mL/100 g |
The nickel content is the toughness mechanism here — it is what carries the impact values down to −60 °F — and it is also the reason this wire is not interchangeable with a mild-steel E71T-1 in a procedure that limits alloy content.
Lincoln's published optimum settings, 100% CO₂, DC+:
| 0.045 in (1.1 mm) | Optimum 420 in/min wire feed speed, 27 volts, approximately 200 amps. Published deposition range across the operating window is 1.5–4.4 kg/hr at 85–88% efficiency. |
|---|---|
| 0.052 in (1.3 mm) | Optimum 300 in/min wire feed speed, 26 volts, approximately 210 amps. |
| 1/16 in (1.6 mm) | Optimum 300 in/min wire feed speed, 26 volts, approximately 280 amps. |
These are the manufacturer's published optimum points inside a wider operating range, not a substitute for a qualified procedure. Deposition efficiency of 85–88% is normal for a gas-shielded flux-cored wire and should be used when converting a solid-wire deposition estimate to this consumable.
| 0.045 in (1.1 mm) — ED034864 | The most controllable diameter of the three and the usual choice for out-of-position work, thinner sections, and root/fill passes where heat input is capped. Optimum around 200 A. |
|---|---|
| 0.052 in (1.3 mm) — ED034865 | The middle ground: more deposition than 0.045 in while still practical vertical-up. Optimum around 210 A at 300 in/min. |
| 1/16 in (1.6 mm) — ED034866 | Highest deposition. Optimum around 280 A. Needs a feeder, liner, and gun rated for 1/16 in cored wire, and is normally used on heavy plate in the flat and horizontal positions. |
- What does E81T1-K2C-JH4 mean?
- Reading the AWS A5.29 classification: "E" electrode, "8" 80 ksi tensile strength class, "1" all positions, "T1" tubular rutile flux with spray transfer, "K2" the low-alloy nickel-bearing chemistry group, "C" 100% CO₂ shielding, "J" improved impact toughness at a lower test temperature, and "H4" a diffusible hydrogen limit of 4 mL per 100 g of deposited metal.
- What shielding gas does it need?
- 100% CO₂ at 40–50 CFH. Lincoln designed and tested the wire on CO₂; the published mechanical properties correspond to that gas.
- Does it keep its toughness after stress relief?
- Yes — that is one of its published design points. Lincoln reports typical Charpy V-notch of 120–147 J (89–108 ft·lbf) after 1 hour at 621 °C (1150 °F), alongside 477–488 MPa yield and 575–580 MPa tensile.
- What is Q2 Lot®?
- Lincoln's lot-level certification programme: a certificate showing the actual deposit chemistry and mechanical properties for the specific lot, available online. Use it when a class society, code, or customer requires certified rather than typical values.
- Why does the packaging matter for an H4 wire?
- Diffusible hydrogen in the deposit comes largely from moisture. The ProTech® foil bag is a moisture barrier that keeps the wire at its rated hydrogen level in storage. Once opened, store the spool in a dry, conditioned environment — an H4 designation describes wire that has been handled correctly.
- Is this the same as UltraCore 81Ni1C-H Plus?
- No. Both are 80 ksi class, all-position, 100% CO₂, H4 flux-cored wires, but they are different chemistry groups: 81K2C-H Plus is the K2 group with 1.54–1.72% typical nickel, while 81Ni1C-H Plus is the Ni1 group formulated to accommodate specifications that cap nickel at 1%. If your procedure limits nickel content, that distinction decides the choice.
- Which diameter should I order?
- 0.045 in (ED034864) for out-of-position and controlled-heat-input work, 0.052 in (ED034865) as a general production compromise, and 1/16 in (ED034866) for maximum deposition on heavy plate in flat and horizontal positions. All three ship on the 33 lb spool.
All three published diameters are stocked as individual listings: 0.045 in, 33 lb spool (ED034864) | 0.052 in, 33 lb spool (ED034865) | 1/16 in, 33 lb spool (ED034866) | All Welding Wire
— signed: SEO Silo-chat