Quick answer: Nickel 201 is the low-carbon version of Nickel 200 and is normally preferred when commercially pure nickel components will be exposed above 315°C (600°F). Nickel 200 remains a practical choice for lower-temperature caustic, chemical and electrical applications. N4, N5 and N6 are Chinese pure-nickel designations; they should not be treated as automatic one-to-one substitutes for UNS N02200 or N02201 without checking the governing standard and the actual material certificate.
Nickel 200, Nickel 201, N4, N5 and N6 at a Glance
| Grade | Key distinction | Procurement note |
|---|---|---|
| Nickel 200 / UNS N02200 | Commercially pure wrought nickel with carbon up to the applicable specification limit | Commonly specified to ASTM B160 for bar and rod |
| Nickel 201 / UNS N02201 | Low-carbon commercially pure nickel | Preferred for elevated-temperature exposure where graphitization must be controlled |
| N4 | Chinese low-carbon pure-nickel designation | Confirm the exact GB/T standard, chemistry and mechanical properties |
| N5 and N6 | Chinese pure-nickel designations with different chemistry limits | Do not accept an “equivalent” statement without a standard cross-check and MTC |
What Is Nickel 200 Round Bar?
Nickel 200, UNS N02200, is commercially pure wrought nickel with useful mechanical properties, good thermal and electrical conductivity and resistance in many reducing, neutral and alkaline environments. Round bar is machined into shafts, fasteners, valve components, electrical parts and chemical-processing hardware.
For bar procurement, ASTM B160 Nickel 200 round bar should be specified by grade, standard edition, diameter, length, condition, tolerance and surface. “Pure nickel bar” by itself is not enough because product condition and chemistry affect fabrication and service limits.
What Is Nickel 201 Round Bar?
Nickel 201, UNS N02201, is the low-carbon version of Nickel 200. The carbon limit is the central distinction: the lower carbon content reduces susceptibility to graphitization during prolonged elevated-temperature exposure. Special Metals identifies Nickel 201 as the preferred grade for service above 315°C (600°F), subject to the full operating environment and design requirements.
ASTM B160 Nickel 201 round bar is used for caustic evaporator components, plater bars, combustion-related hardware, electronic parts and other applications where commercially pure nickel and low carbon are required.
Why Carbon Content Changes the Selection
Nickel 200 and 201 have similar high nickel content, but carbon influences microstructural stability at elevated temperature. If Nickel 200 is exposed for extended periods in the critical temperature range, graphitic carbon can form and reduce ductility. Nickel 201's lower carbon limit is intended to address this risk.
This does not mean Nickel 201 is always “better.” For a lower-temperature component, Nickel 200 may fully satisfy the process and code requirements. Buyers should select the grade from operating temperature, duration, chemical medium, stress, fabrication route and governing equipment standard—not from a generic comparison table.
How N4, N5 and N6 Relate to International Nickel Grades
N4, N5 and N6 are encountered in Chinese-market documents and export inquiries. Their chemistry limits can resemble commercially pure nickel grades, but equivalence depends on the cited GB/T product standard, product form and edition. An N4 certificate should not be relabeled as Nickel 201 solely because both are described as low-carbon pure nickel.
A technically complete comparison checks:
- the exact standard number and edition;
- nickel plus cobalt minimum;
- carbon, iron, copper, manganese, silicon and sulfur limits;
- product form and delivery condition;
- mechanical-property requirements by diameter;
- heat treatment, testing and marking rules.
If a drawing requires UNS N02201 to ASTM B160, quote and certify that requirement directly. If the customer accepts an alternative Chinese grade, obtain written engineering approval before substitution.
ASTM B160 and Product Form
ASTM B160 covers nickel rod and bar. It does not automatically cover plate, sheet, pipe, tube or forgings; those forms use different specifications. A frequent procurement error is copying the correct alloy name with the wrong product standard.
| Order item | Required information |
|---|---|
| Material | Nickel 200 / N02200 or Nickel 201 / N02201 |
| Product standard | ASTM B160 or ASME SB160, including the required edition |
| Condition | Hot finished, cold finished, annealed, peeled, ground or polished as applicable |
| Dimensions | Diameter, cut length, tolerances, straightness and machining allowance |
| Inspection | Chemistry, tensile testing, dimensions, PMI, UT or third-party inspection when ordered |
| Documentation | EN 10204 3.1 MTC and heat-number traceability |
Caustic and Chemical Service
Commercially pure nickel is well known for useful resistance in caustic alkalis, particularly when contaminants and oxidizing species are controlled. Actual corrosion behavior depends on concentration, temperature, aeration, impurities, velocity and equipment design. Welds, crevices and contact with dissimilar metals may change local conditions.
For high-consequence chemical equipment, request process-specific corrosion data and design review. A material certificate confirms that the bar meets the ordered material specification; it does not guarantee suitability for every chemical environment.
Machining and Surface Requirements
Nickel 200 and 201 are ductile and can produce continuous chips. Machining plans should use rigid equipment, sharp tools, positive feed and effective chip control. When the bar will become a long shaft or precision component, specify straightness, diameter tolerance, surface roughness and machining allowance before quotation.
Available finishes may include hot-finished, turned, peeled, ground, polished and bright conditions. Ground or peeled stock can reduce preparation, while hot-finished stock may be preferred where additional machining allowance is required.
Certificate and Inspection Checklist
- Confirm UNS grade and ASTM B160 on the purchase order and MTC.
- Match the heat number on each bundle or piece to the certificate and packing list.
- Check carbon carefully when Nickel 201 is required.
- Review mechanical values against the ordered diameter and delivery condition.
- State PMI, UT, dimensional reports or third-party inspection before production.
- Keep cut pieces traceable by transferred marking or controlled package identification.
Which Grade Should You Choose?
Choose Nickel 200 for suitable lower-temperature caustic, chemical, electrical and general industrial components when the governing specification permits it. Choose Nickel 201 for elevated-temperature exposure above 315°C (600°F) or when the project specifically requires low-carbon UNS N02201. Use N4, N5 or N6 only when the relevant Chinese standard is accepted and verified against the project requirements.
Information to Send with an RFQ
Provide grade, UNS designation, standard and edition, bar diameter, length, quantity, condition, surface, tolerance, straightness, application temperature, chemical medium, machining requirement, inspection plan, certificate type, marking, packaging and destination. Clear RFQ data prevents wrong-grade substitution and shortens technical review.
FAQ
Can Nickel 200 be used above 315°C?
Nickel 201 is generally preferred for prolonged exposure above 315°C because its lower carbon content reduces graphitization risk. Final selection must follow the design code and service conditions.
Are N4 and Nickel 201 identical?
They may be compared as low-carbon pure-nickel grades, but they are not automatically interchangeable. Verify the exact standards, chemistry, properties and customer approval.
What standard applies to Nickel 200 and 201 round bar?
ASTM B160 / ASME SB160 is commonly specified for rod and bar. Other product forms require their applicable specifications.
Post time: Mar-05-2026