ERNiCrMo-3 vs ERNiFeCr-2 Nickel Alloy Filler Wire Comparison

Among nickel‑based alloy welding consumables, ERNiCrMo‑3 and ERNiFeCr‑2 are two of the most frequently ordered AWS A5.14 grades. Despite similar appearances and overlapping nominal nickel content, their alloy design, strengthening mechanisms, and application windows are fundamentally different.

Incorrect selection between them may lead to premature weld failure, reduced service life, or even catastrophic fracture. This article provides a systematic technical comparison to support correct material selection and procurement decisions.

ERNiCrMo‑3 is a nickel‑chromium‑molybdenum solid‑solution strengthened filler metal. It contains a minimum of 58% nickel, 20–23% chromium, 8–10% molybdenum, and 3.15–4.15% niobium (plus tantalum). It is designed primarily for outstanding resistance to pitting, crevice corrosion, and stress‑corrosion cracking in aggressive chloride‑containing and acidic environments. 

The weld deposit achieves its mechanical properties through solid‑solution strengthening without requiring post‑weld heat treatment (PWHT). Typical applications include welding Inconel 625, Incoloy 825, 25‑6Mo super‑austenitic stainless steels, and various dissimilar joints between nickel alloys and stainless or carbon steels.

ERNiFeCr‑2 is a nickel‑iron‑chromium precipitation‑hardenable filler metal. It contains 50–55% nickel, 17–21% chromium, about 20% iron (balance), 4.75–5.5% niobium, 2.8–3.3% molybdenum, and minor additions of titanium and aluminium. Its high strength derives from a controlled precipitation of γ″ and γ′ phases during a mandatory post‑weld solution anneal and double‑aging heat treatment.

Without this heat treatment, the as‑welded strength is only about 600 MPa, far below its potential of 1200–1300 MPa. Typical applications include welding Inconel 718, 706, and X‑750 alloys, used in aircraft engine components, gas turbine rotors, and nuclear reactor internals where high mechanical strength and creep resistance up to 700°C are required.

• Molybdenum: The 8–10% Mo in ERNiCrMo‑3 provides excellent resistance to localized corrosion in seawater, sour gas, and acid environments. The 3% Mo in ERNiFeCr‑2 is insufficient for such aggressive media. Pitting and crevice corrosion will initiate much earlier.
• Niobium: Higher Nb in ERNiFeCr‑2 enables precipitation hardening, but also promotes Laves phase formation and segregation during solidification. Consequently, ERNiFeCr‑2 is more sensitive to weld solidification cracking. Low heat input and strict interpass temperature control are mandatory.
• Iron: The higher iron content makes ERNiFeCr‑2 noticeably less expensive than ERNiCrMo‑3, since nickel is far more costly than iron. However, using ERNiFeCr‑2 in place of ERNiCrMo‑3 purely for cost saving is a downgrade that compromises corrosion performance.

Note: Because the two filler metals look almost identical, incoming material inspection should include positive material identification (PMI) using portable XRF or OES to verify molybdenum content (≥8% for ERNiCrMo‑3, ≤4% for ERNiFeCr‑2).

Corrosion‑Dominated Applications

• Chemical reactors, offshore platform equipment, FGD systems, and pulp bleaching plants.
• Medium‑to‑low temperatures, chloride or sulphide‑containing media.
• Recommended choice: ERNiCrMo‑3. Its superior pitting and SCC resistance outlasts ERNiFeCr‑2 by a significant margin, and no PWHT is needed.

Strength‑ and Creep‑Dominated Applications

• Aircraft engine casings, turbine discs, fasteners, and high‑pressure rotating parts.
• Service temperatures between 500°C and 700°C with high cyclic or sustained loads.
• Recommended choice: ERNiFeCr‑2, but only if the user has the capability to perform the full solution‑and‑aging heat treatment. Without that, the strength advantage is lost.

Dissimilar Metal Welds (Nickel Alloy to Stainless or Carbon Steel)

• Expansion coefficient mismatch and dilution are major concerns.
• Recommended choice: ERNiCrMo‑3, because of its higher plasticity, tolerance to dilution, and lack of PWHT requirement. Dissimilar assemblies often cannot be heat treated as a whole.

For ERNiCrMo‑3

• Preheating is generally not required. For heavy sections or high restraint, 100°C preheat may be applied.
• Interpass temperature should be kept ≤150°C to minimize excessive heat accumulation and reduce the risk of detrimental phases such as Laves phase.
• Shielding: argon or argon‑helium mixtures.
• Post-weld heat treatment is generally not required, and welded components can normally be placed directly into service. Special heat treatments may be applied for specific requirements but can alter weld microstructure and mechanical properties.

For ERNiFeCr‑2

• Heat input should be carefully controlled ≤ 1.5 kJ/mm for critical applications to minimize Nb segregation, Laves phase formation, and hot cracking susceptibility.
• Preheating is generally not required. For thick or highly restrained components, low-temperature preheat may be considered.
• Interpass temperature should typically be maintained below 150–200°C depending on welding procedure requirements.
• PWHT is required when precipitation-hardening properties comparable to Alloy 718 base metal are needed. A typical aging treatment may include solution treatment followed by aging at 720°C/620°C stages. Without proper aging, the weld metal cannot achieve its full precipitation-strengthened condition, and residual stress may increase the risk of strain-age cracking.

1. What is the main difference between ERNiCrMo-3 and ERNiFeCr-2?

ERNiCrMo-3 is a Ni-Cr-Mo filler wire strengthened by solid solution strengthening, providing excellent resistance to pitting, crevice corrosion, and stress corrosion cracking. ERNiFeCr-2 is a precipitation-hardenable filler wire that achieves high strength through solution treatment and aging.

The key difference is that ERNiCrMo-3 is optimized for corrosion resistance, while ERNiFeCr-2 is designed for high mechanical strength and creep resistance.

2. What is ERNiCrMo-3 filler wire used for?

ERNiCrMo-3 filler wire is mainly used for welding Inconel 625 and other nickel-based alloys requiring excellent corrosion resistance. Common applications include chemical processing, offshore equipment, marine systems, sour gas service, and dissimilar welding between nickel alloys and stainless steels.

3. Can ERNiCrMo‑3 be used to weld Inconel 718 base material?

No. ERNiCrMo‑3 lacks the titanium and aluminium needed to form strengthening precipitates in the 718 base metal. The joint strength will be only 50–60% of the base metal, and creep life is severely reduced.

4. Can ERNiFeCr‑2 be used to weld Inconel 625 base material?

Not recommended. Besides the corrosion resistance loss, the higher niobium in ERNiFeCr‑2 reacts unfavourably with molybdenum in the 625 base, increasing hot cracking susceptibility by an estimated 40% or more.

5. How can ERNiCrMo-3 and ERNiFeCr-2 filler wires be identified?

Visual inspection is not reliable because both filler wires have a similar appearance. Identification should be based on material certificates or PMI testing such as XRF or OES, with molybdenum content being one of the key differences.

6. Are ERNiCrMo-3 and ERNiFeCr-2 suitable for the same welding processes?

Both filler wires can be used for GTAW and GMAW processes. However, ERNiFeCr-2 requires stricter heat input control and post-weld heat treatment, while ERNiCrMo-3 can usually be used in the as-welded condition.

Choosing the correct nickel alloy filler wire depends on the base material, service environment, operating temperature, mechanical requirements, and welding procedure.

If you are unsure whether ERNiCrMo-3 or ERNiFeCr-2 is suitable for your application, send us your material grade, welding process, required diameter, and application details. Our technical team can help recommend the appropriate filler wire and provide a quotation based on your requirements.

We supply AWS 5.14 ERNiCrMo-3 and ERNiFeCr-2 filler wires with complete material documentation, including chemical composition certificates and inspection reports. Contact us for technical consultation or a customized quotation.

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