2.4603 is the German material number for a high-chromium nickel-chromium-iron corrosion-resistant alloy with additions of molybdenum, tungsten and copper. This datasheet presents the material within the Werkstoff-Nummer (DIN / EN) designation system.
A high-chromium nickel-chromium-iron alloy with additions of molybdenum, tungsten and copper, 2.4603 gives superior corrosion resistance over most other nickel- and iron-based alloys in commercial phosphoric acids and in complex highly oxidizing acid environments. It is especially valued for "wet process" phosphoric acid (P₂O₅) service in the fertiliser industry, and also resists nitric and mixed oxidizing acids, ferric and cupric ions, and chloride-induced localized attack and stress-corrosion cracking. The low carbon content resists grain-boundary precipitation in the weld heat-affected zone, so the alloy 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 wet-process phosphoric acid evaporators and heat exchangers, nitric and mixed-acid service, pickling operations, fertiliser and pesticide manufacture, gold extraction, and nuclear-waste processing.
| Property | Value | Unit |
|---|---|---|
| Density | 8.22 | g/cm³ |
| Melting point | 1371 | °C |
| Elastic modulus | 200 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 12.8 | µm/m·°C |
| Thermal conductivity (20 °C) | 10.2 | W/m·K |
| Specific heat (20 °C) | 460 | J/kg·K |
| Structure | Austenitic (FCC), single phase | — |
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Nickel | Ni | Balance | — | Base element; SCC / reducing-media resistance |
| Chromium | Cr | 28.0 | 31.5 | Oxidizing-acid / phosphoric-acid resistance |
| Iron | Fe | 13.0 | 17.0 | Base alloying; cost-effectiveness |
| Molybdenum | Mo | 4.0 | 6.0 | Pitting / crevice / reducing-acid resistance |
| Tungsten | W | 1.5 | 4.0 | Localized-corrosion resistance; passivation |
| Copper | Cu | 1.0 | 2.4 | Reducing-acid resistance |
| Cobalt | Co | — | 5.0 | Passivation; residual |
| Niobium | Nb (+Ta) | 0.30 | 1.50 | Stabiliser |
| Carbon | C | — | 0.03 | Low; resists sensitisation |
Solution-annealed condition, per EN reference data for W.Nr. 2.4603.
| Condition | Property | Value |
|---|---|---|
| Solution annealed | Tensile strength (Rm) | ≥620 MPa |
| Solution annealed | 0.2% proof strength (Rp0.2) | ≥240 MPa |
| Solution annealed | Elongation (A5) | ≥45 % |
| As-welded | Corrosion resistance | Retained (low carbon) |
| — | Elastic modulus | 200 GPa |
Values per EN reference data; the low carbon content preserves corrosion resistance in the weld heat-affected zone. Confirm against the inspection certificate (EN 10204).
| Environment | Performance | Notes |
|---|---|---|
| Wet-process phosphoric acid (P₂O₅) | Excellent | Primary application; superior to most alloys |
| Nitric / oxidizing acids | Excellent | High chromium content |
| Mixed acids (nitric/HF, nitric/HCl) | Excellent | Pickling and complex acid service |
| Pitting / crevice corrosion | Very Good | Molybdenum + tungsten |
| Chloride stress-corrosion cracking | Very Good | Lower susceptibility than stainless steels |
The high chromium content, supported by molybdenum, tungsten, cobalt and copper, gives outstanding resistance in wet-process phosphoric acid and in complex oxidizing and mixed-acid environments, with good resistance to localized attack and stress-corrosion cracking.
A single-phase solid-solution alloy; not hardenable by precipitation. Properties are set by solution annealing.
Solution Anneal Solution anneal at approximately 1175 °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.
Good weldability; readily welded by the gas-tungsten-arc and gas-metal-arc processes with matching filler, and resistant to grain-boundary precipitation in the as-welded condition owing to its low carbon content. Post-weld heat treatment is typically unnecessary, even for critical acid service.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Good | 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, heavy-duty tooling |
| Speeds | Slow speeds, positive feeds, no dwelling |
| Coolant | Ample water-based 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 |
|---|---|---|
| Fertiliser | Wet-process phosphoric acid evaporators | Phosphoric-acid resistance |
| Chemical process | Acid heat exchangers, reactors | Mixed-acid resistance |
| Metal finishing | Nitric/HF pickling hardware | Oxidizing-acid resistance |
| Mining / nuclear | Gold extraction, waste processing | Aggressive-media resistance |
| Product Form | DIN / EN Standard | Notes |
|---|---|---|
| Plate, sheet and strip | DIN 17750 · W.Nr. 2.4603 | High-Cr Ni-Cr-Fe alloy |
| Bar, rod and forgings | DIN 17752 · W.Nr. 2.4603 | — |
| Seamless pipe and tube | DIN 17751 · W.Nr. 2.4603 | — |
| Inspection documents | EN 10204 | — |
High-chromium nickel-chromium-iron corrosion-resistant alloy with molybdenum, tungsten and copper. W.Nr. 2.4603.
| W.Nr. | Cr % | Mo % | Fe % | Best Used For |
|---|---|---|---|---|
| 2.4603 | 28–31.5 | 4–6 | 13–17 | High-Cr Ni-Cr-Fe; wet-process phosphoric acid, oxidizing/mixed acids |
| 2.4619 | 21–23.5 | 6–8 | 18–21 | Ni-Cr-Fe-Mo-Cu; reducing acids, FGD, sour OCTG (G-3) |
| 2.4858 | 19.5–23.5 | 2.5–3.5 | balance | Ni-Fe-Cr-Mo-Cu; sulfuric / phosphoric acid (825) |
| 2.4856 | 20–23 | 8–10 | ≤5 | General Ni-Cr-Mo-Nb corrosion / strength (625) |
| 2.4819 | 14.5–16.5 | 15–17 | 4–7 | Reducing media, wet chlorine (C-276) |




