ASTM B127/B127M is the standard specification by ASTM International covering rolled nickel-copper alloy plate, sheet, and strip — universally known as Monel 400 (UNS N04400). With approximately 65% nickel and 30% copper, Monel 400 delivers the best seawater corrosion resistance among all commonly available engineering alloys, excellent resistance to hydrofluoric acid, and immunity to chloride stress corrosion cracking. The companion specification ASME SB127 is adopted for ASME Code-stamped pressure equipment.

Zhengzhou Huitong (HT Pipe) supplies ASTM B127 / ASME SB127 compliant plate, sheet & strip with full Mill Test Certificates (MTC) per EN 10204 3.1. 

1. Standard Scope & Designation

ASTM B127/B127M covers nickel-copper alloy (UNS N04400 — Monel 400) plate, sheet, and strip. Monel 400 combines the corrosion resistance of nickel with the unique properties of copper to deliver outstanding performance in seawater, hydrofluoric acid, and caustic soda environments, with excellent resistance to chloride stress corrosion cracking.

2. Grades Covered by ASTM B127

ASTM B127 covers the following grades. Each grade is defined by its UNS number and specific chemistry targeted at different service environments.

3. Chemical Composition

Values are weight percent maximum unless shown as a range. Heat analysis. Per ASTM B127 Table 1.

4. Mechanical Property Requirements

All values are minimum requirements. Tensile testing per ASTM E8/E8M.

5. Heat Treatment Requirements

6. Testing & Inspection Requirements

7. Dimensions & Dimensional Tolerances

ASTM B127 covers plate up to 3 in (76 mm) thick, sheet from 0.018–0.250 in (0.46–6.35 mm), and strip from 0.005–0.250 in (0.13–6.35 mm). Standard widths: 48–96 in (1220–2440 mm). Monel 400 plate is available in hot-rolled annealed and as-rolled conditions.

8. Industries & Applications

9. ASTM B127 vs ASTM B575 (Ni-Cr-Mo Alloys — C-276, C-22) — Comparison

10. Related Standards

11. How to Order — Required Information

12. Frequently Asked Questions

Q: Why is Monel 400 the benchmark alloy for seawater service?

Monel 400's approximately 65% Ni – 30% Cu composition creates a naturally protective surface film that resists seawater corrosion at all velocities — from stagnant conditions to high-velocity (> 100 ft/s / 30 m/s) flow. Unlike stainless steels that rely on oxygen for passive film maintenance and can suffer crevice corrosion, Monel 400 does not require oxygen and is immune to chloride stress corrosion cracking (SCC). It resists biofouling moderate pitting and offers an excellent strength-to-corrosion-resistance ratio at a fraction of the cost of Ni-Cr-Mo alloys.

Q: Is ASTM B127 Monel 400 suitable for hydrofluoric acid service?

Yes — Monel 400 is the benchmark alloy for hydrofluoric acid (HF) service. It shows excellent resistance to anhydrous HF and aqueous HF up to approximately 80% concentration at ambient temperature, and to dilute solutions (≤10%) at elevated temperatures. For anhydrous HF alkylation units in refineries, Monel 400 is the standard material for valve trim, instrument components, and heat exchanger tubes. It is not recommended for hot concentrated HF (> 50% at boiling) or HF solutions containing oxidizing agents. For these conditions, C-276 (ASTM B575) should be considered.

Q: Can Monel 400 plate be welded?

Yes. Monel 400 plate is readily weldable by GTAW (TIG), GMAW (MIG), SMAW (stick), and SAW processes. The recommended filler metal is ERNiCu-7 (AWS A5.14 / ENiCu-7) — essentially matching Monel 400 composition. No preheat required. Interpass temperature should be controlled below 150°C (300°F). Post-weld heat treatment (PWHT) is not required for corrosion resistance, but stress relief at 540–565°C (1000–1050°F) may be applied to reduce residual stress. The weld zone has corrosion resistance comparable to the base metal.

Q: What is the difference between Monel 400 and K-500?

Monel 400 (UNS N04400, ASTM B127) is a solid-solution-strengthened Ni-Cu alloy with approximately Ni 65% – Cu 30%. Monel K-500 (UNS N05500) has the same Ni-Cu base but adds 2.3–3.1% Al + 0.35–0.85% Ti, enabling precipitation hardening (age hardening) to roughly double the yield strength (YS ≥ 620 MPa / 90 ksi in aged condition vs 193 MPa / 28 ksi for annealed Monel 400). K-500 is used for pump shafts, fasteners, springs, and marine propeller shafts requiring high strength. Monel 400 is the general-purpose corrosion-resistant grade for plate, pipe, and process equipment.

Q: What are the temperature limits for ASTM B127 Monel 400?

For continuous corrosion-resistant service, Monel 400 is suitable from cryogenic temperatures (−196°C / −320°F) to approximately 540°C (1000°F). It maintains excellent toughness and ductility at cryogenic temperatures with no ductile-to-brittle transition. For structural applications, the maximum service temperature is approximately 540°C (1000°F), above which oxidation and strength loss become significant. In seawater, Monel 400 performs well up to approximately 120°C (250°F). In caustic soda (NaOH), maximum recommended temperature is approximately 200°C (400°F) for concentrations up to 75%.

Request a Quote — ASTM B127 Monel 400 (UNS N04400) Plate, Sheet & Strip

Zhengzhou Huitong (HT Pipe) supplies ASTM B127 / SB127 UNS N04400 Monel 400 plate, sheet, and strip for seawater, HF acid, and caustic service. Full EN 10204 3.1 CMTRs from qualified nickel alloy mills. Competitive lead times and cut-to-size capability.