These six are the commercially pure nickels — not the nickel alloys such as Monel, Inconel or Hastelloy, which are covered elsewhere on this site. Pure nickel is bought for one headline property above all others: resistance to caustic alkalis, where Special Metals describe it as unexcelled, handling sodium hydroxide at every concentration and temperature including molten. It also maintains product purity in food and pharmaceutical handling, conducts heat and electricity well, and is ferromagnetic with useful magnetostrictive properties — the one magnetic material in our non-ferrous range. The six divide into two families: 200 and 201 are the process grades differing only in carbon, and 205, 211, 233 and 270 are electronic grades controlled to much tighter residual levels under ASTM F3 and F290.
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Nickel and sulfur form a nickel–nickel sulfide (Ni–Ni₃S₂) eutectic that melts at about 645 °C. If sulfur is present on the surface when nickel is heated above that temperature, the eutectic forms as a liquid film along the grain boundaries and the component fails intergranularly — catastrophically, without warning, and permanently. The sulfur almost always comes from the workshop rather than the process: marking crayons and inks, cutting and forming lubricants, grease, oil, paint, temperature-indicating sticks, even fingerprints. The rule is absolute — nickel must be thoroughly cleaned and degreased before any heating operation, whether annealing, stress relieving, welding, brazing or hot forming, and only sulfur-free marking materials and lubricants may be used on it. Furnace atmospheres must be sulfur-free too; a fuel-fired furnace burning sulfur-bearing fuel is not acceptable. In service, nickel should not be used in sulfur-bearing atmospheres at temperature at all.
Carbon sets the temperature ceiling, and it is the only difference between Alloy 200 and Alloy 201. Nickel 200 permits 0.15% carbon, which precipitates as graphite at the grain boundaries above about 315 °C and embrittles the metal. Nickel 201 restricts carbon to 0.02%, leaving too little for graphitisation. The ASME Boiler and Pressure Vessel Code reflects this directly: both grades are approved under Section VIII Division 1, but Nickel 200 only to 315 °C (600 °F) and Nickel 201 to 677 °C (1250 °F) — a difference of more than 360 degrees from a single element. If a nickel component will run hot, specify 201.
Nickel is ferromagnetic — the one magnetic material in our non-ferrous range. Copper, titanium, zirconium, tantalum and aluminium fasteners are all non-magnetic; nickel is strongly magnetic below its Curie temperature of about 360 °C. Where a non-magnetic fastener is required — MRI and medical imaging, magnetometer or compass proximity, sensitive instrumentation — commercially pure nickel is the wrong choice. Where magnetic or magnetostrictive behaviour is wanted it is exactly the point, and Nickel 205 is chemistry-modified specifically to raise the magnetostrictive coefficient.
Good in reducing conditions, poor in oxidising ones. Beyond caustics, nickel resists distilled and natural waters, neutral and alkaline salts, the organic acids, dry chlorine and fluorine gas at temperature, and deaerated non-oxidising mineral acids. It is attacked by oxidising acids — nitric acid in particular, which it has essentially no resistance to — by oxidising salts such as ferric and cupric chloride, hypochlorites and persulfates, by ammonia and ammonium hydroxide above about 1% when oxygen is present, and by moist sulfur dioxide. Nickel also pits and suffers crevice attack in stagnant seawater, which is why the copper-nickels and Monel rather than pure nickel are the marine choices in this family.
Commercially pure nickel is not covered by the ASTM nonferrous fastener standards. ASTM F468 and F467 do carry nickel materials — alloys 400, 405, 500, 625, 276, 335, 59 and 686 — but Nickel 200 and 201 are not among them, and neither are the electronic grades. That is worth stating plainly, because the F468 nickel listing invites the assumption that all nickel materials are covered. Fasteners in these grades are manufactured to the mill product standards (B160, B161, B162, B163 for 200 and 201; ASTM F3 and F290 for the electronic grades) with thread conformance to the applicable ASME or ISO standard. On strength, annealed pure nickel runs about 380–520 MPa tensile against 830 MPa for an A325 structural bolt — it is specified for caustic resistance, purity, magnetic behaviour and conductivity, not for load. Where strength is needed in a nickel-base material, Monel 400, Monel K-500 and Inconel 625 are the alternatives, and all three are covered by F468.
Annealed nickel has low hardness with good ductility and a relatively low work-hardening rate, so it spins, deep draws, bends and cold heads well and can be cold worked to moderately high strength while keeping useful ductility — Special Metals data show annealed rod at 55 to 40% elongation. Nickel 201, with its lower carbon, is softer still and is the grade to specify for severe forming. Machining is the harder discipline: nickel behaves like an austenitic stainless, work hardening ahead of the tool and glazing the surface if the tool is allowed to rub rather than cut. Exotic Alloy machines nickel on rigid setups with sharp positive-rake tooling, a positive feed that keeps the cut below the work-hardened layer, reduced surface speeds and generous flood lubricant. Threads are rolled rather than cut wherever section permits.
Nickel 200, 201 and 270 data from Special Metals technical bulletins; Nickel 205 and 233 to ASTM F3; Nickel 211 to ASTM F290.
| Grade | UNS | Nickel min | Carbon max | Distinguishing Feature | Specification | Max Service | Chosen For |
|---|---|---|---|---|---|---|---|
| Alloy 200 | N02200 | 99.0% | 0.15% | The base commercially pure grade | ASTM B160/B161/B162/B163 | 315 °C (ASME VIII) | Caustic and general process duty |
| Alloy 201 | N02201 | 99.0% | 0.02% | Low carbon — no graphitisation | ASTM B160/B161/B162/B163 | 677 °C (ASME VIII) | Hot service and severe forming |
| Alloy 205 | N02205 | 99.0% | 0.10% | 0.010–0.08% Mg added | ASTM F3 Grade 2 | Not code listed | Magnetostrictive transducers |
| Alloy 211 | N02211 | 93.7% | 0.20% | 4.25–5.25% Mn — an alloy, not pure Ni | ASTM F290 | Not code listed | Electron device and lamp wire |
| Alloy 233 | N02233 | 99.0% | 0.10% | Controlled low residuals; 0.01–0.10% Mg | ASTM F3 Grade 1 | Not code listed | Active cathodes, vacuum tube anodes |
| Alloy 270 | N02270 | 99.9% | 0.02% | Powder metallurgy; purest grade | ASTM F3 | Not code listed | Hydrogen thyratrons, resistance thermometers |
Note two things in this table. First, Alloy 201 is identical to Alloy 200 in every specified element except carbon, and that one difference more than doubles the permitted service temperature under the ASME code — 315 °C against 677 °C. Second, Alloy 211 is not a commercially pure nickel at all: at 93.7% nickel minimum with 4.25–5.25% manganese it is a nickel-manganese alloy, harder than the pure grades and supplied principally as wire, and it should not be substituted for them where product purity or maximum conductivity governs. Only Alloys 200 and 201 are ASME Boiler and Pressure Vessel Code listed; the four electronic grades are specified under the ASTM F series and are not code materials. Density across the family is 8.89–8.91 g/cm³ and all six are ferromagnetic, with Curie temperatures of 353–360 °C.
We are committed to delivering zero-defect nickel fasteners. All products undergo rigorous testing including PMI (Positive Material Identification), chemical analysis with carbon reported explicitly, sulfur analysis, mechanical testing in the supplied condition, dimensional inspection and full traceability with EN 10204 3.1 certification. Certification of sulfur-free thermal processing and full residual analysis on the ASTM F3 electronic grades are available at order stage.
Exotic Alloy exports nickel fasteners and components to chlor-alkali, caustic soda, chemical processing, food and pharmaceutical, electronics and electron-device clients worldwide. Our dedicated logistics team ensures secure export packaging and timely deliveries by sea and air freight with full customs documentation support.