ESAB Welding & Cutting Products has introduced Shield-Bright NiCrMo-3, a 625-type electrode for manual and automatic flux cored wide-weave welding of 9% nickel steel in the vertical-up (3G) position and using 75% argon/25% CO2 shielding gas.
“We specifically developed Shield-Bright NiCrMo-3 for a U.S. LNG tank fabricator that had shifted from a 1/8 in. (3mm) vs. 5/32 in. (4 mm) root gap using a ceramic backer,” says David Hamilton, Director of Sales, Stoody, an ESAB brand. “Wider gaps are challenging for high-nickel wires because the puddle tends to be sluggish and have a high crown, but Shield-Bright NiCrMo-3 creates an extremely flat bead profile with excellent tie-in at the toes of the weld. It almost runs like mild steel wire, reducing concerns related to hot cracking susceptibility and stress concentrations.”
The wire is classified as AWS A5.34/5.34M:2018 ENiCrMo3T1-4 wire and has a tensile strength >100 ksi (690 MPa) and a Charpy impact toughness of >52 ft lb. (70 J) at -320oF (-196oC). Shield-Bright NiCrMo-3, delivers mechanical properties that exceed customer requirements because ESAB carefully controls weld metal composition.
During development, ESAB engineers used a weld data analysis system to prove that the wire welds with excellent arc stability and amperage control. Lab tests in the 3G position showed a deposition rate of 5.25 lbs/hr (2.4 kg/hr) using a 0.045-in. (1.2 mm) wire. The slag released easily to reduce risk of slag inclusions and lower-post weld cleaning time and costs.
Last year, ESAB introduced Cryo-Shield Ni9, a NiCrMo alloy flux cored wire used for all-position welding of 9% Ni steel LNG fuel and storage tanks with 100% CO2 shielding gas. This modified 625-type wire offers excellent crack resistance and is superior to conventional NiCrMo-3 wires. Mechanical properties are similar to Hastelloy ENiMo-13 flux cored wires. Typical as-welded mechanical properties are a yield strength of 440 MPa, tensile strength of 730 MPa, elongation of 44% and an impact value of 65 J at -196 oC.
“We developed Cyro-Shield Ni9 in response to ship propulsion systems shifting from heavy fuel oil to LNG fuel to reduce oxide emissions,” says Neil Farrow, Global Product Manager – Cored Wires, ESAB. “This wire also meets the needs of LNG storage tank fabricators and other 9% Ni steel applications. In benchmark tests against leading 625-alloy wires, Cryo-Shield Ni9 provided superior crack-resistance tolerance, which is especially critical for root welding. Customer field tests with 100% CO2 shielding gas also confirmed better tolerance to porosity formation, wet-out for a flatter bead crown and slag release compared to conventional 625-alloy wires. In addition, the slag system supports all-position welding, including over-head.”
Further, because it uses 100% CO2 shielding gas instead of an argon blend, it lowers operating cost. The wire carries approvals from the ABS, BV, DNV GL, KR, LR and CCS classification societies.
