NiMo16Cr15W is the EN symbol designation for a nickel-molybdenum-chromium-tungsten corrosion-resistant alloy. This datasheet presents the material within the EN symbol designation system.
By far the most widely used member of the C family, NiMo16Cr15W is a wrought, low-carbon corrosion-resistant alloy offering universal corrosion resistance across a wide range of severe environments. Its high molybdenum and nickel contents give exceptional resistance to pitting, crevice corrosion and reducing media such as hydrochloric and sulfuric acids, while its chromium content provides resistance to oxidizing media. It is one of the few materials able to withstand wet chlorine gas, hypochlorite and chlorine dioxide. The very low carbon and silicon contents minimise grain-boundary carbide precipitation during welding, so the alloy resists intergranular attack in the weld heat-affected zone and can be used in the as-welded condition. It is a single-phase, solid-solution alloy supplied in the solution-annealed condition.
Typical applications include chemical and petrochemical processing, flue-gas desulfurisation and pollution-control scrubbers and stack liners, pulp-and-paper, and waste-treatment equipment.
| Property | Value | Unit |
|---|---|---|
| Density | 8.89 | g/cm³ |
| Melting range | 1325–1370 | °C |
| Elastic modulus | 205 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 11.2 | µm/m·°C |
| Thermal conductivity (20 °C) | 9.8 | W/m·K |
| Specific heat (20 °C) | 427 | J/kg·K |
| Structure | Austenitic (FCC), single phase | — |
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Nickel | Ni | Balance | — | Base element; reducing-media resistance |
| Molybdenum | Mo | 15.0 | 17.0 | Pitting / crevice / reducing-acid resistance |
| Chromium | Cr | 14.5 | 16.5 | Oxidizing-media resistance |
| Tungsten | W | 3.0 | 4.5 | Reducing-media / localized-corrosion resistance |
| Iron | Fe | 4.0 | 7.0 | Residual |
| Cobalt | Co | — | 2.50 | Residual |
| Vanadium | V | — | 0.35 | Residual |
| Carbon | C | — | 0.010 | Very low; minimises carbide precipitation |
Solution-annealed condition, per EN reference data for W.Nr. 2.4819.
| Condition | Property | Value |
|---|---|---|
| Solution annealed | Tensile strength (Rm) | ≥690 MPa |
| Solution annealed | 0.2% proof strength (Rp0.2) | ≥283 MPa |
| Solution annealed | Elongation (A5) | ≥40 % |
| As-welded | Corrosion resistance | Retained (low carbon) |
| — | Elastic modulus | 205 GPa |
Values per EN reference data; the very low carbon content preserves corrosion resistance in the weld heat-affected zone. Confirm against the inspection certificate (EN 10204).
| Environment | Performance | Notes |
|---|---|---|
| Reducing acids (HCl, H₂SO₄) | Excellent | High molybdenum + nickel |
| Wet chlorine / hypochlorite / ClO₂ | Excellent | One of few alloys that resist these |
| Pitting / crevice corrosion | Excellent | Molybdenum + tungsten |
| Stress-corrosion cracking | Excellent | High nickel content |
| Oxidizing acids (HNO₃) | Good | Chromium-bearing |
The high molybdenum and tungsten content gives outstanding resistance in reducing and chloride-bearing environments — including wet chlorine, hypochlorite, ferric and cupric chlorides, contaminated acids and seawater — with exceptional resistance to localized attack; resistance in strongly oxidizing acids is good but lower than higher-chromium grades.
A single-phase solid-solution alloy; not hardenable by precipitation. Properties are set by solution annealing.
Solution Anneal Solution anneal at approximately 1120 °C and rapidly quench (water or rapid air cool) to dissolve secondary phases and retain maximum corrosion resistance. The alloy is not strengthened by heat treatment; cold work raises strength.
Excellent weldability; readily welded by the gas-tungsten-arc and gas-metal-arc processes with matching filler, and used in the as-welded condition owing to its very low carbon content. No post-weld heat treatment is normally required.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Excellent | Matching filler |
| GMAW / MIG | Good | Matching filler |
| SMAW / stick | Good | Matching electrode |
Weld with matching filler and clean surfaces; the alloy may be used as-welded without post-weld heat treatment.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Machinability | Difficult; work-hardens, rigid setups, sharp tooling |
| Speeds | Slow speeds, positive feeds, no dwelling |
| Coolant | Ample coolant |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Good; work-hardens, anneal between heavy operations |
| Hot forming | 1010–1175 °C; solution anneal afterward |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Chemical / petrochemical | Reactors, evaporators, heat exchangers, piping | Reducing-acid + chloride resistance |
| Pollution control | Scrubbers, stack liners, ducts, dampers | Wet-chlorine + acid resistance |
| Pulp & paper | Bleaching equipment | Chlorine / chloride resistance |
| Marine / waste | Components, waste-treatment hardware | Seawater + mixed-media resistance |
| Product Form | DIN / EN Standard | Notes |
|---|---|---|
| Plate, sheet and strip | DIN 17750 · W.Nr. 2.4819 | NiMo16Cr15W |
| Bar, rod and forgings | DIN 17752 · W.Nr. 2.4819 | — |
| Seamless pipe and tube | DIN 17751 · W.Nr. 2.4819 | — |
| Inspection documents | EN 10204 | — |
Nickel-molybdenum-chromium-tungsten corrosion-resistant alloy. W.Nr. 2.4819 (NiMo16Cr15W).
| EN Symbol | Mo % | Cr % | W % | Best Used For |
|---|---|---|---|---|
| NiMo16Cr15W | 15–17 | 14.5–16.5 | 3–4.5 | Family standard Ni-Mo-Cr-W; reducing media, wet chlorine, mixed acids |
| NiCr21Mo14W | 12.5–14.5 | 20–22.5 | 2.5–3.5 | Higher-chromium; better oxidizing-media resistance (C-22) |
| NiMo16Cr16Ti | 14–17 | 14–18 | — | Thermally stable Ni-Cr-Mo alloy (C-4) |
| NiCr22Mo9Nb | 8–10 | 20–23 | — | General Ni-Cr-Mo-Nb corrosion / strength (625) |
| NiMo28 | 27–32 | 1–3 | — | Ni-Mo alloy for hydrochloric acid (B-3) |




