What Exactly Is 2.4602 (NiCr21Mo14W)?
The designation 2.4602 originates from the European DIN/EN material numbering system, specifically DIN 17744 and EN 10269. It refers to a wrought nickel alloy whose full compositional name — NiCr21Mo14W — directly encodes its principal alloying elements: nickel base, approximately 21% chromium, 14% molybdenum, and tungsten. The same alloy composition is produced under various proprietary trade names by different alloy manufacturers worldwide.
What distinguishes 2.4602 from other premium nickel alloys is its exceptionally high chromium content of 20–22.5%. This gives it a decisive corrosion resistance advantage in oxidizing acid environments (hot concentrated nitric acid, mixed HNO₃/H₂SO₄), while the 12.5–14.5% molybdenum and 2.5–3.0% tungsten simultaneously ensure outstanding performance in reducing acid environments (HCl, H₂SO₄). The result is the most versatile corrosion-resistant wrought nickel forging alloy for mixed acid service currently available.
- DIN/EN Designation
2.4602- Full Compositional Name
NiCr21Mo14W- PREN Value (min. spec.)
- ≥ 56
- Density
- 8.50 g/cm³
- Melting Range
- 1325–1370 °C
- Governing Standards
- DIN 17744 / EN 10269 / ASTM B564
How to read the compositional name "NiCr21Mo14W"
European compositional naming follows the pattern: base metal (Ni) + principal alloying additions with nominal percentage. "NiCr21Mo14W" = nickel base, ~21% Cr, ~14% Mo, tungsten present (no percentage suffix means W is present at specification minimum). This system identifies the alloy family and key elements at a glance — without consulting a datasheet.
Full Chemical Composition and Role of Each Element
Understanding what each alloying element contributes is critical when specifying 2.4602 for a particular service environment. The table below lists the full composition per DIN 17744 alongside the specific metallurgical function of each element.
| Element | Specification Range | Nominal % | Primary Metallurgical Function |
|---|---|---|---|
| Nickel (Ni) | Balance (~55–58%) | ~57% | Austenitic FCC matrix; primary resistance to chloride-induced stress corrosion cracking (SCC) |
| Chromium (Cr) | 20.00–22.50% | 21% | Forms passive Cr₂O₃ oxide film; primary contributor to oxidizing acid resistance (HNO₃); high-temperature oxidation resistance |
| Molybdenum (Mo) | 12.50–14.50% | 14% | Inhibits pit initiation in chloride media; critical for reducing acid resistance (HCl, H₂SO₄); contributes 3.3× weight to PREN calculation |
| Tungsten (W) | 2.50–3.00% | 2.75% | Synergistic with Mo to suppress crevice corrosion; stabilizes passive film repassivation in mixed acid environments |
| Iron (Fe) | ≤ 3.00% | ~1.5% | Controlled at low levels; excess Fe above 3% degrades oxidizing acid resistance |
| Carbon (C) | ≤ 0.010% | <0.01% | Ultra-low carbon prevents intergranular sensitization — Cr carbide precipitation at grain boundaries during heat treatment or welding |
| Silicon (Si) | ≤ 0.080% | <0.05% | Deoxidizer; restricted to minimize TCP phase precipitation during high-temperature processing |
| Copper (Cu) | ≤ 0.50% | <0.3% | Minor beneficial effect in dilute H₂SO₄; tightly controlled to prevent galvanic corrosion issues |
Ultra-Low Carbon (≤ 0.010%) Is Non-Negotiable — Always Verify on the MTC
Carbon above 0.015% can precipitate Cr₂₃C₆ carbides at grain boundaries during heat treatment or welding — called sensitization — depleting chromium from the matrix and creating pathways for intergranular corrosion. Always verify the actual carbon content on the mill test certificate (MTC) of every production heat before accepting material.
Understanding the PREN Value of 2.4602
The Pitting Resistance Equivalent Number (PREN) ranks alloys by resistance to chloride-induced pitting corrosion. The formula for nickel alloys is:
For 2.4602, using nominal composition (21% Cr, 14% Mo, N ≈ 0): PREN ≈ 21 + (3.3 × 14) = 67.2. The specification minimum of ≥ 56 is a conservative lower bound. Material produced at the higher end of composition ranges typically achieves PREN 65–68. Importantly, PREN does not capture oxidizing acid resistance — 2.4602's high chromium content gives it a practical advantage in mixed acid service that the PREN formula does not fully reflect.
PREN Comparison: 2.4602 vs. Major Competing Alloys
PREN values are estimates based on nominal alloy compositions per published standards. Proprietary alloy trade names are not used above to avoid trademark confusion; the values represent the alloy compositions as standardized under DIN/EN designations.
If you are evaluating 2.4602 for a project and need standard stock dimensions, weight ranges, or available product forms, see our custom 2.4602 open die forgings and rolled rings page for full technical details and lead-time information.
Melting Methods: AM/VR, VIM/VAR, and AM/VAR Explained
The melting process used to produce 2.4602 ingots directly affects internal cleanliness, inclusion content, and microstructural homogeneity. Three primary melting routes are defined in the industry. When sourcing 2.4602 forgings, engineers should specify the required melting method explicitly in their RFQ — the choice of supplier and whether they can provide a specific melting method must be confirmed directly with the manufacturer.
AM/VR — Air Melt + Vacuum Refined
Initial melting in an air-atmosphere electric arc or induction furnace, followed by vacuum degassing and ladle refining. Produces material with acceptable inclusion content for most industrial applications at the most competitive cost.
VIM/VAR — Vacuum Induction Melted + Vacuum Arc Refined
Full vacuum melting throughout: VIM eliminates dissolved oxygen and nitrogen; VAR remelting under vacuum reduces microsegregation and achieves the highest cleanliness levels for heavy-section ingots.
AM/VAR — Air Melt + Vacuum Arc Refined
Air melting for cost efficiency, with VAR remelting to improve ingot homogeneity and reduce macro-segregation in heavy forgings. A practical cost-performance balance for high-pressure service.
Always specify the melting method explicitly on your drawing or RFQ
State the melting method unambiguously: e.g., "2.4602 per DIN 17744, Method B (VIM/VAR), Solution Annealed + Water Quenched, EN10204 3.1 MTC required." Leaving the melting method unspecified allows the manufacturer to supply AM/VR material by default. Confirm with your chosen manufacturer which melting methods they can supply before placing an order.
Heat Treatment: Solution Annealing and Water Quench Requirements
2.4602 is invariably supplied and used in the solution annealed and water quenched condition. This heat treatment dissolves all secondary phases that form during hot working, restoring the material to its optimal single-phase austenitic microstructure with maximum corrosion resistance.
- Solution Anneal Temperature
- 1100–1150 °C (2012–2102 °F)
- Minimum Hold Time (Forgings)
- 1 hr per 25 mm section thickness
- Quench Method
- Rapid water quench — mandatory; air cooling is unacceptable
- Resulting Microstructure
- Single-phase austenite; ASTM grain size ≥ 3
Water quenching immediately from the solution anneal temperature is critical. Slow cooling through the 950–700 °C range allows precipitation of P-phase and μ-phase intermetallic compounds at grain boundaries, which can reduce pitting resistance significantly and embrittle heavy-section forgings.
Minimum Mechanical Properties After Solution Anneal + Water Quench
The high elongation (≥ 45%) reflects the fully recrystallized single-phase austenitic structure. This combination of strength and ductility makes 2.4602 forgings suitable for both static pressure components and dynamically loaded rotating equipment.
Industry Applications: Where 2.4602 Is Specified and Why
The combination of oxidizing acid resistance, reducing acid resistance, chloride tolerance, and mechanical robustness positions 2.4602 as the material of choice in six severe-service industries. Specific end-use compliance requirements (e.g. nuclear qualification, pressure vessel codes) vary by project and country — buyers should confirm applicable requirements with their engineering team and the relevant authority.
Oil & Gas — Sour Service
Wellhead valve bodies, subsea manifold connectors, and production separators in H₂S + CO₂ + chloride brine environments. Sour service components typically require compliance with NACE MR0175 / ISO 15156 — buyers should confirm this requirement with their project specifications.
Nuclear Power Generation
Primary coolant loop components, valve seats, and instrumentation housings. Nuclear applications involve stringent national regulatory requirements and specific qualification processes — always verify applicable codes (ASME, RCC-M, JSME etc.) with your project authority before material selection.
Flue Gas Desulfurization (FGD)
Absorber tower spray nozzle header rings, agitator shaft assemblies, damper frames, and outlet duct expansion joints in mixed H₂SO₃/H₂SO₄/HCl environments at 50–80 °C. One of the globally highest-volume applications for 2.4602 open die forgings.
Seawater Desalination
MED and MSF evaporator tube sheets, brine heater heads, and high-pressure pump bodies exposed to concentrated seawater chlorides and elevated temperatures. 2.4602 offers a viable alternative to titanium for cost-sensitive large-diameter ring applications.
Pharmaceutical & Fine Chemical
API synthesis reactor vessels, agitator assemblies, and heat exchanger heads where GMP purity standards restrict metal ion contamination and where mixed HNO₃/H₂SO₄ or HCl media are used in synthesis steps.
Waste Incineration & Flue Gas Cleaning
Wet electrostatic precipitator internals, flue gas scrubber spray rings, and quench chamber liners in HCl + SO₂ + HF + moisture environments at 100–250 °C — one of the most demanding combined acid-halide service conditions.
All six application categories above are supported by our manufacturing capability. For product-specific information — including available sizes, weights, and order requirements for each application — visit the 2.4602 forging parts for FGD, oil & gas, and desalination product page.
2.4602 vs. C276-Grade, C22-Grade, and 625-Grade Alloys
Engineers evaluating 2.4602 typically compare it against three common alternatives. The table below compares these alloy compositions and corrosion performance based on published standard specifications. All proprietary trade names refer to compositions standardized under the DIN/EN/UNS designations shown — see trademark disclaimer below.
| Property | 2.4602 (NiCr21Mo14W) | C276-grade (2.4819) | C22-grade alloy | 625-grade (2.4856) |
|---|---|---|---|---|
| Chromium Content | 20–22.5% | 14.5–16.5% | 20–22.5% | 20–23% |
| Molybdenum Content | 12.5–14.5% | 15–17% | 12.5–14.5% | 8–10% |
| Tungsten Content | 2.5–3.0% | 3–4.5% | 2.5–3.5% | — |
| Calculated PREN (nominal) | ≥56 / ≈67 (nominal) | ≈ 71 | ≈ 61 | ≈ 51 |
| Oxidizing acid (HNO₃) | Excellent | Good | Excellent | Moderate |
| Reducing acid (HCl, H₂SO₄) | Excellent | Excellent | Excellent | Good |
| Mixed acid / FGD environments | Excellent | Very Good | Excellent | Moderate |
| Chloride pitting & crevice | Very Good | Excellent | Excellent | Good |
| High-temp strength (>600 °C) | Moderate | Moderate | Moderate | Excellent |
| Relative material cost | Medium–High | High | High | Medium |
Ratings are relative within this alloy group and based on published corrosion engineering literature. Environment-specific coupon corrosion testing is always recommended before final material selection for critical applications.
Decision Framework: When to Specify 2.4602 vs. Its Alternatives
Choose 2.4602 when…
- Process involves oxidizing acids (HNO₃) or mixed oxidizing/reducing media such as FGD absorbers
- Service combines chlorides with acids at temperatures up to 300 °C
- Best balance of oxidizing and reducing acid resistance is needed in one alloy
- Budget is constrained vs. C276-grade but mixed acid performance is required
Consider alternatives when…
- Pure reducing acid only (HCl, H₂SO₄ with no oxidizer) → C276-grade (higher Mo content)
- Structural service above 600 °C → 625-grade (superior creep resistance)
- Seawater without acid → Super Duplex 2507 or Ti Grade 2 for cost
- Weld overlay cladding → C22-grade alloys (better weldability)
Applicable Standards and Documentation Requirements
When procuring 2.4602 NiCr21Mo14W forging parts, specifying the correct standard and documentation level is as important as the material designation itself. The table below summarises the standards most commonly referenced across engineering, inspection, and procurement functions.
Material Composition Standards
Product Form Standards (Forgings)
Inspection and Documentation
| Document / Test | What It Is | Typical Use |
|---|---|---|
| EN10204 Type 3.1 MTC | Mill test certificate issued and signed by the manufacturer's own authorized quality department | Standard commercial orders — most industrial applications |
| EN10204 Type 3.2 MTC | Mill test certificate co-signed by the manufacturer AND an independent third-party inspection body (TÜV, Bureau Veritas, Lloyds, SGS, or equivalent). Note: the manufacturer does not issue the 3.2 certificate alone — it requires a third party. | Pressure-critical, offshore, or nuclear applications where buyer's specification requires independent witness |
| Positive Material Identification (PMI) | XRF testing of finished forgings at delivery to confirm alloy composition | High-alloy critical service; typically required by EPCs and major owner operators |
| Ultrasonic Testing (UT) | Volumetric inspection per ASTM A388 to detect internal flaws | Heavy-section forgings, typically ≥ 75 mm section thickness |
| Liquid Penetrant Testing (PT) | Surface inspection per ASTM E165 | Surface-connected discontinuities on machined surfaces |
About EN10204 3.2 Certificates
A 3.2 MTC is not a certification that a manufacturer "holds" — it is a document issued for a specific production batch, co-signed by both the manufacturer's inspector and an accredited independent third-party inspector who witnesses testing. If your project requires 3.2, confirm with your manufacturer that they can arrange third-party witness inspection and that this is included in your purchase order.
Procurement Checklist: How to Correctly Specify 2.4602 Forging Parts
Incomplete RFQ documentation is the most common source of specification disputes in nickel alloy forging procurement. Include all of the following items in your RFQ or purchase order:
| Material designation | State "2.4602 per DIN 17744" or "ASTM B564 UNS N06200" — do not rely on proprietary trade names alone |
| Melting method | State Method A (AM/VR), Method C (AM/VAR), or Method B (VIM/VAR) — confirm availability with your manufacturer |
| Heat treatment condition | State "Solution Annealed + Water Quenched" explicitly — never accept air-cooled or unspecified condition |
| MTC type required | State EN10204 3.1 (manufacturer-issued) or EN10204 3.2 (requires independent third-party inspector — arrange separately) |
| NDT requirements | Specify UT (ASTM A388), PT (ASTM E165), acceptance criteria class, surface condition, and reporting format |
| Certified drawing | Include drawing with material call-out, dimensional tolerances, surface finish specification, and marking requirements |
| Special compliance needs | State any end-use compliance requirements (sour service, pressure vessel code, nuclear) so the manufacturer can confirm whether they can meet them |
| PMI at delivery | State whether Positive Material Identification (XRF) is required at delivery and by whom |
Once you have completed this checklist, you can request a quote for 2.4602 forgings directly from our product page, which includes standard dimensions, available product forms, and our documentation package.
Frequently Asked Questions About 2.4602 (NiCr21Mo14W)
What is 2.4602 (NiCr21Mo14W)?
2.4602 (NiCr21Mo14W) is a premium wrought nickel-chromium-molybdenum-tungsten superalloy standardized under DIN 17744 and EN 10269. It contains approximately 57% nickel, 20–22.5% chromium, 12.5–14.5% molybdenum, and 2.5–3.0% tungsten, with ultra-low carbon (≤ 0.010%). With a PREN value of ≥ 56 (typically ≈67 at nominal composition), it is one of the most corrosion-resistant wrought nickel alloys available for mixed acid service, widely used in oil & gas, FGD, seawater desalination, and pharmaceutical industries.
What is the PREN value of 2.4602?
The PREN (Pitting Resistance Equivalent Number) of 2.4602 is ≥ 56 per specification minimum, calculated as: PREN = %Cr + 3.3 × %Mo + 16 × %N. Using nominal composition (21% Cr, 14% Mo, N ≈ 0), the typical PREN is approximately 67.2. PREN only predicts chloride pitting resistance — it does not measure oxidizing acid resistance, where 2.4602's high chromium content gives it a distinct performance advantage.
What heat treatment is required for 2.4602 forgings?
2.4602 forgings must be in the solution annealed and water quenched condition. Solution anneal at 1100–1150 °C for minimum 1 hour per 25 mm of section thickness, followed immediately by water quench. Air cooling is never acceptable — slow cooling allows precipitation of secondary phases that significantly reduce corrosion resistance and toughness.
How does 2.4602 compare to C276-grade (2.4819) alloy?
The primary difference is chromium: 2.4602 contains 20–22.5% Cr versus 2.4819's 14.5–16.5% Cr. This gives 2.4602 a decisive advantage in oxidizing acid environments (hot HNO₃, mixed HNO₃/H₂SO₄, FGD). The 2.4819 composition has higher molybdenum (15–17%) and higher calculated PREN (≈71), making it preferred for pure reducing acid or pure chloride service. Note: "Hastelloy® C276" is a registered trademark of Haynes International — the composition is standardized as DIN 2.4819 / UNS N10276.
What is the difference between VIM/VAR and AM/VR melting?
AM/VR (Air Melt + Vacuum Refined) is the standard process for most industrial applications — acceptable inclusion levels, competitive cost. VIM/VAR (Vacuum Induction Melted + Vacuum Arc Refined) is a premium dual-vacuum process producing the highest achievable internal cleanliness and microstructural homogeneity, typically specified for nuclear-grade and ultra-critical pressure components. AM/VAR is an intermediate option for high-pressure oil & gas applications. Always confirm which melting methods your chosen manufacturer can supply before placing your order.
What certifications should I request for 2.4602 forgings?
At minimum, request EN10204 Type 3.1 MTC — issued by the manufacturer's own authorized quality inspector. For pressure-critical applications requiring independent verification, specify EN10204 Type 3.2 MTC, which requires co-signature by an accredited independent third-party inspector (arranged separately). Always independently verify carbon content (≤ 0.010%) on every MTC. For sour service applications, confirm NACE MR0175 / ISO 15156 compliance requirements with your project engineering team.
Key Takeaways: 5 Things Every Engineer Must Know About 2.4602
It is the most versatile wrought nickel alloy for mixed acid service. No other commercially available forging alloy combines oxidizing acid resistance (from 20–22.5% Cr) and reducing acid resistance (from 12.5–14.5% Mo + W) at this performance level in the same material.
PREN ≥ 56 is the specification minimum — nominal composition delivers PREN ≈ 67. Always verify actual Cr and Mo content on the MTC. PREN does not predict oxidizing acid performance — chromium content is the key differentiator in mixed acid service.
Always specify Solution Annealed + Water Quenched. Never accept air-cooled material. Slow cooling through 950–700 °C allows precipitation of secondary phases that irreversibly degrade corrosion resistance and toughness in heavy-section forgings.
Specify the melting method explicitly and confirm capability with your manufacturer. State Method A (AM/VR), Method C (AM/VAR), or Method B (VIM/VAR). Leaving this blank allows the supplier to choose the lowest-cost option by default.
Carbon content (≤ 0.010%) is your primary quality gate — verify it on every MTC. EN10204 3.1 is the standard minimum. If 3.2 is required, arrange independent third-party inspection separately. Carbon above 0.015% on any heat should be a cause for rejection.
Standards and References Cited in This Article
- DIN 17744: Nickel alloys — Chemical composition (German Institute for Standardization)
- EN 10269: Steels and nickel alloys for fasteners with specified properties at elevated and/or low temperatures
- ASTM B564: Standard Specification for Nickel Alloy Forgings (ASTM International)
- EN 10204: Metallic products — Types of inspection documents
- NACE MR0175 / ISO 15156: Petroleum and natural gas industries — Materials for use in H₂S-containing environments
- ASTM A388: Standard Practice for Ultrasonic Examination of Steel Forgings
- ASTM E165: Standard Practice for Liquid Penetrant Examination
- EN 13445-4: Unfired pressure vessels — Part 4: Fabrication
Need Custom 2.4602 (NiCr21Mo14W) Forging Parts?
Jiangsu Liangyi Co., Limited manufactures open die forgings and seamless rolled rings in 2.4602 (NiCr21Mo14W) to ASTM B564, EN 10269, and DIN 17744. ISO 9001:2015 certified · Founded 1997 · 25+ years experience · EN10204 3.1 MTC provided as standard · Export to 50+ countries.