Nickel 200 and Nickel 201 are commercially pure nickel — in both, nickel + cobalt is min 99.0%. They contain no alloying elements such as chromium or molybdenum. The only difference between them is in carbon, but that difference changes the service limits completely.
Carbon and graphitisation
In Nickel 200 carbon is max 0.15%, in Nickel 201 max 0.02%.
When pure nickel spends a long time above roughly 300 °C, the carbon in the structure begins to precipitate as graphite at the grain boundaries. Graphite films weaken the grain boundaries; the material loses its ductility and becomes brittle. This is called graphitisation and it is irreversible.
Because carbon is already very low in Nickel 201, that mechanism is practically switched off. This is why 201 is used instead of 200 in any part that will work above 300 °C.
It has a second advantage as well: the low carbon makes the material softer and easier to form. 201 is preferred for parts requiring deep drawing and cold forming.
Comparison in numbers
| PROPERTY | Nickel 200 | Nickel 201 |
|---|---|---|
| Nickel + Cobalt | min 99.0% | min 99.0% |
| Carbon (C) | max 0.15% | max 0.02% |
| Iron (Fe) | max 0.40% | max 0.40% |
| Manganese (Mn) | max 0.35% | max 0.35% |
| Silicon (Si) | max 0.35% | max 0.35% |
| Sulphur (S) | max 0.01% | max 0.01% |
| Copper (Cu) | max 0.25% | max 0.25% |
| Density | 8890 kg/m³ | 8890 kg/m³ |
| Melting range | 1435 – 1446 °C | 1435 – 1446 °C |
| Service temperature limit | ~300 °C | suitable above 300 °C |
| UNS | N02200 | N02201 |
| W.Nr (DIN/EN) | 2.4060 · 2.4066 | 2.4061 · 2.4068 |
| AMS | — | 5553 |
Values are taken from our product datasheets; section thickness and the applied heat treatment regime change the result.
Which one, and when?
Nickel 200 is sufficient — caustic soda (sodium hydroxide) production and storage equipment, food processing vessels, electronic components, any application at room temperature and below 300 °C. It is easier to source.
Nickel 201 is required — caustic evaporators working above 300 °C, chlor-alkali cell components, high-temperature chemical equipment, parts formed by deep drawing. If the specification calls out AMS 5553, the grade being asked for is 201.
Both grades perform far above stainless steels and other nickel alloys in caustic environments — especially in concentrated sodium and potassium hydroxide. That is the most distinctive advantage of pure nickel.
Neighbouring alloys
For seawater and acid environments the move is to nickel–copper alloys: see our Monel 400 – K-500 comparison. For oxidation resistance at high temperature, Inconel 600 is used.
Technical datasheets
Nickel 200 — chemical composition, mechanical values, standard equivalents
Nickel 201 — chemical composition, mechanical values, standard equivalents
Both grades are supplied to order in round bar, flat bar, plate, sheet, pipe and forged forms. Contact us for a quotation.