Hastelloy C-59 (UNS N06059, W.Nr. 2.4605, EN designation NiCr23Mo16Al) is a fourth-generation Ni-Cr-Mo alloy engineered to outperform earlier grades — including C-276 and C-22 — in the most aggressive chloride and mixed-acid service conditions. Its high chromium (22–24%) content ensures outstanding oxidation resistance, while 15–16.5% molybdenum provides class-leading resistance to reducing media such as concentrated HCl and H₂S-bearing sour gas streams.
The deliberate restriction of carbon to ≤0.01% and silicon to ≤0.10% — lower than any other commercial Ni-Cr-Mo alloy — suppresses intermetallic phase precipitation during welding and hot working, eliminating the need for post-weld solution annealing in field fabrications. This makes C-59 the preferred choice for complex fabricated assemblies where repeatable corrosion performance must be guaranteed across the weld fusion zone.
The alloy is certified to NACE MR-0175 / ISO 15156 for sour-service at elevated temperatures, and its PREN of approximately 72 exceeds that of C-276 (≈67), giving it superior resistance to localized corrosion in high-chloride production brines.
Section 2: Equivalent Grades
Hastelloy C-59 / UNS N06059 is a nickel-chromium-molybdenum superalloy developed by VDM Metals under the trade name Nicrofer 5923 hMo, distinguished by ultra-low carbon (≤0.01%) and silicon (≤0.10%) contents that virtually eliminate sensitization and deliver superior corrosion performance in both oxidizing and reducing acid environments encountered throughout oil and gas production and processing.
Section 1: Introduction
N06059 Equivalent Grades & Standards
Hastelloy C-59 is recognized under multiple national and international standards. The table below maps all relevant designations used globally.
| Standard Body | Designation / Grade | Applicable Form |
|---|---|---|
| UNS (USA) | N06059 | All wrought forms |
| ASTM / ASME | B574 / SB574 (Bar) B575 / SB575 (Plate / Sheet) B619 / SB619 (Welded Pipe) B564 / SB564 (Forgings) |
Bar, Plate, Pipe, Forging |
| EN / DIN (Europe) | W.Nr. 2.4605 / NiCr23Mo16Al DIN 17744 / DIN 17750–17754 |
All wrought forms |
| ISO | NW 2.4605 | Wrought identification |
| GB (China) | NS3311 | Bar, Plate, Pipe |
| Trade Name (VDM Metals) | Nicrofer 5923 hMo / VDM® Alloy 59 | All forms |
| NACE | MR-0175 / ISO 15156 Compliant | Sour-service components |
| AWS (Welding) | ERNiCrMo-13 (Wire) — filler 2.4609 | Weld consumables |
Section 3: Oil & Gas Applications
Oil & Gas Applications of Hastelloy C-59
C-59’s ultra-clean composition and superior PREN make it the premium selection for the following oil and gas components, particularly where C-276 has proven marginal:
- High-pressure packer mandrels
- Completion tool housings
- Perforating gun carriers
- Bridge plug bodies
- Safety valve components
- Gate and globe valve stems
- Valve ball & seat rings
- Tubing hanger bodies
- Wellhead connector pins
- Check valve internals
- Subsea manifold block inserts
- Umbilical end terminations
- Flowline connector bolts
- Riser clamp components
- ROV tooling shafts
- Amine absorber tower internals
- H₂S scrubber spray nozzles
- Acid gas injection quills
- Sulfur recovery vessel liners
- Glycol dehydration internals
- Shell & tube exchanger baffles
- Pump impellers & wear rings
- Centrifugal pump shafts
- Crude cooler tube sheets
- Separator internals
- Sour-service stud bolts & nuts
- High-pressure flange bolting
- Butt-weld & socket-weld fittings
- Compression tube fittings
- Instrument-line adapters
Section 4: Supply / Dimensions
Supply Forms & Size Range — Hastelloy C-59 Bar
SHUNFU METAL holds prompt-delivery stock of Hastelloy C-59 in all mill and forged forms. Tight-tolerance, rough-machined, and ultrasonic-tested conditions are available on request.
| Form | Size Range | Condition | Standard |
|---|---|---|---|
| Hot-Rolled Round Bar | Ø 6 – 250 mm | Annealed & Pickled | ASTM B574 |
| Cold-Drawn Round Bar | Ø 3 – 80 mm | Bright Annealed | ASTM B574 |
| Forged Round Bar | Ø 80 – 600 mm | Forged + Annealed | ASTM B564 |
| Hot-Rolled Flat Bar | T 6–150 mm × W 10–400 mm | Annealed & Pickled | ASTM B575 |
| Forged Flat Bar / Block | T 20–300 mm × W 50–800 mm | Forged + Annealed | ASTM B564 |
| Hex Bar | AF 8 – 100 mm | Bright / Pickled | ASTM B574 |
Standard lengths: 1,000–6,000 mm. Cut-to-length and rough-machined blanks available. MTC 3.1 per EN 10204 supplied with every order.
Section 5: Chemical Composition
Chemical Composition — ASTM B574 / UNS N06059
The composition below conforms to ASTM B574 / UNS N06059 and EN W.Nr. 2.4605 requirements. SHUNFU METAL performs in-house OES verification on every heat, with third-party ICP confirmation available on request.
| Element | Min % | Max % |
|---|---|---|
| Ni | Bal. | Bal. |
| Cr | 22.0 | 24.0 |
| Mo | 15.0 | 16.5 |
| Fe | — | 1.50 |
| Co | — | 0.30 |
| Al | 0.10 | 0.40 |
| Mn | — | 0.50 |
| Si | — | 0.10 |
| Cu | — | 0.50 |
| C | — | 0.010 |
| P | — | 0.025 |
| S | — | 0.015 |
Key differentiator vs. C-276: higher Cr (22–24% vs. 14.5–16.5%) for oxidizing media resistance; Si strictly capped at 0.10% — roughly half that of C-276 — preventing silicide-phase precipitation. Aluminum addition (0.10–0.40%) further stabilizes the austenitic matrix at elevated temperatures.
Section 6: Mechanical Properties
Mechanical Properties — Hastelloy C-59 Bar (Solution Annealed)
Standard heat treatment: solution anneal at 1,100–1,180°C (2,012–2,156°F), rapid water or air quench. Properties at room temperature per ASTM B574 and VDM Metals datasheet. SHUNFU METAL conducts full tensile and hardness testing on each production lot with NIST-traceable calibration.
| Form | UTS (MPa) | YS 0.2% (MPa) | Elongation (%) | Hardness |
|---|---|---|---|---|
| Round Bar / Rod | ≥ 690 | ≥ 310 (typ. 340) | ≥ 45 (typ. 55–65) | ≤ 35 HRC / ~200 HB |
| Plate / Sheet | 690 – 830 | 310 – 420 | ≥ 40 | 85–92 HRB |
| Forged Bar (heavy) | ≥ 690 | ≥ 310 | ≥ 30 | ≤ 35 HRC (NACE MR-0175) |
Physical constants: Density 8.6 g/cm³ · Modulus of Elasticity 210 GPa · Thermal Conductivity 10.4 W/m·K at 20°C · Electrical Resistivity 1.26 Ω·mm²/m · Melting Range 1,380–1,420°C.
SHUNFU Quality Section
How SHUNFU METAL Ensures Quality
All C-59 stock is sourced from VIM+ESR or AOD-refined heats from approved VDM Metals / Special Metals-qualified mills. Full heat-number traceability is maintained from melt to finished bar.
Each heat is re-analyzed by SHUNFU’s in-house spark emission spectrometer before any cutting operation. Critical elements — especially C, Si, Cr, Mo — are verified against ASTM B574 limits. Material mix-up is eliminated at source.
Forged bars ≥ Ø100 mm are 100% ultrasonically tested to ASTM A388 / EN 10228-3, Class S3. Internal segregation, piping, and crack indications are screened before shipment.
Tensile, yield, elongation, hardness, and chemical analysis are reported on EN 10204 Type 3.1 Mill Test Certificates. Digital certificates are available with every shipment — no exceptions for sour-service orders.
Need Hastelloy C-59 / N06059 to the specification above?
Send the size, condition, quantity and any NACE or PMI requirements — we reply with mill availability, lead time and a priced offer, usually within one working day.