Views: 39 Author: Rachel Publish Time: 2024-08-06 Origin: Site
Material: UNS N06455 | DIN 2.4610 | GB/T NS335
Standard: ASTM B575 / ASME SB575
Manufacturer: Jinie Technology (Jiangsu) Co., Ltd., Wuxi, China
JN Alloy manufactures and supplies Hastelloy C4 plate and sheet to ASTM B575 and ASME SB575, with full mill test certification and third-party inspection available. Stock is maintained in common thicknesses; custom dimensions and cut-to-size service are available for project requirements.
Hastelloy C4 (UNS N06455) is a nickel-chromium-molybdenum alloy plate recognized as the most thermally stable of the common C-family alloys. Its defining characteristic is resistance to grain boundary precipitation — meaning it does not form harmful carbide or secondary phases at the grain boundaries when exposed to temperatures between 649°C and 1038°C. This makes it uniquely suitable for fabricated equipment that will be welded without post-weld heat treatment and then placed directly into high-temperature, corrosive service.
Compared to Hastelloy C276, C4 contains no tungsten and has a tightly controlled iron content (≤3%), which eliminates the primary mechanism responsible for sensitization in the weld heat-affected zone. This makes C4 plates the preferred choice for pressure vessels, reactor vessels, and heat exchanger shells in acid-service applications where welded assemblies cannot be post-weld annealed.
Chemical Composition (per ASTM B575-20, Table 1)
| Element | Hastelloy C4 (UNS N06455) |
|---|---|
| Nickel (Ni) | Balance |
| Chromium (Cr) | 14.0 – 18.0% |
| Molybdenum (Mo) | 14.0 – 17.0% |
| Iron (Fe) | ≤ 3.0% |
| Cobalt (Co) | ≤ 2.0% |
| Titanium (Ti) | ≤ 0.7% |
| Manganese (Mn) | ≤ 1.0% |
| Silicon (Si) | ≤ 0.08% |
| Carbon (C) | ≤ 0.015% |
| Phosphorus (P) | ≤ 0.04% |
| Sulfur (S) | ≤ 0.03% |
The combination of high chromium (up to 18%) and high molybdenum (up to 17%) provides resistance to both oxidizing and reducing acid environments. The ultra-low carbon (≤0.015%) is the key to preventing sensitization during welding.
| Property | Minimum Value |
|---|---|
| Tensile Strength | 690 MPa (100 ksi) |
| Yield Strength (0.2% offset) | 276 MPa (40 ksi) |
| Elongation in 2 inches | 40% |
| Hardness (max) | 100 HRB |
The 40% minimum elongation is exceptional for a corrosion-resistant alloy at this strength level. It means C4 plate can be cold-formed, deep-drawn, and spun into complex shapes — vessel heads, expansion bellows, and formed components — without cracking.
| Property | Value |
|---|---|
| Density | 8.6 g/cm³ |
| Melting Range | 1335 – 1380°C |
| Specific Heat (20°C) | 408 J/kg·K |
| Thermal Conductivity (20°C) | 10.1 W/m·K |
| Electrical Resistivity (20°C) | 124 µΩ·cm |
| Elastic Modulus (20°C) | 211 kN/mm² |
| Thermal Expansion (100–300°C) | 10.9 – 12.5 × 10⁻⁶/K |
All plates and sheets are supplied per ASTM B575 / ASME SB575.
| Parameter | Range |
|---|---|
| Thickness | 1.0 mm – 100 mm |
| Width | Up to 2,500 mm |
| Length | Up to 12,500 mm |
| Surface Finish | No. 1 (HR Annealed), 2B, 2D, BA, No. 4 |
| Condition | Hot-rolled annealed & pickled (HRAP), Cold-rolled annealed (CRA) |
| Tolerances | Per ASTM B906 (sheet and strip) and ASTM B975 (plate) |
Surface Finish Selection Guide:
No. 1 (HR Annealed & Pickled): Standard for plate ≥ 4.8 mm. Mill surface with no additional finishing. Used where surface aesthetics are not critical — pressure vessel shells, heat exchanger tubesheets, structural components.
2B (Cold-rolled, bright annealed): Smooth, moderately reflective surface. Standard choice for sheet in chemical process equipment where a clean surface is needed for hygiene or corrosion resistance.
No. 4 (Brushed/polished): Fine brushed finish. Preferred for pharmaceutical reactors, food-contact applications, and any service where crevices from surface roughness must be minimized.
BA (Bright Annealed): Mirror-like finish. Specified for sanitary piping, high-purity applications, and ornamental use.
| Environment | Performance | Notes |
|---|---|---|
| Hydrochloric acid (all concentrations) | Excellent | Outstanding below 60°C; best of the C-family at reducing HCl |
| Sulfuric acid (up to 70%) | Excellent | Maintains resistance up to boiling point at moderate concentrations |
| Phosphoric acid (wet-process) | Excellent | Preferred alloy for phosphoric acid heat exchangers containing HF and Cl⁻ impurities |
| Nitric acid | Good | Better than C276 due to lower Fe content; suitable for dilute HNO₃ |
| Chloride-containing solutions | Excellent | High Mo prevents pitting and crevice corrosion |
| Seawater / brine | Excellent | No pitting in ambient seawater; suitable for marine process equipment |
| Formic and acetic acids | Excellent | Widely used in organic acid process lines |
| High-temperature oxidizing gases (to 1040°C) | Good | Suitable for combustion environments with moderate oxidation |
Key advantage over 316L stainless steel: In 10% HCl at 50°C, Hastelloy C4 plate shows a corrosion rate below 0.05 mm/year. Under the same conditions, 316L stainless steel corrodes at rates exceeding 2.0 mm/year — more than 40 times faster. This explains why C4 is specified for HCl service where 316L is completely unsuitable.
This is the most common selection question for C-family alloy plate. Here is a direct data-based comparison:
| Property | Hastelloy C4 | Hastelloy C276 | Hastelloy C22 |
|---|---|---|---|
| UNS | N06455 | N10276 | N06022 |
| Cr (%) | 14–18 | 14.5–16.5 | 20–22.5 |
| Mo (%) | 14–17 | 15–17 | 12.5–14.5 |
| W (%) | None | 3–4.5 | 2.5–3.5 |
| Fe (%) | ≤ 3 | 4–7 | 2–6 |
| Thermal stability at 650–1040°C | Excellent | Moderate | Good |
| Resistance to HCl (reducing) | Excellent | Excellent | Good |
| Resistance to HNO₃ (oxidizing) | Good | Moderate | Excellent |
| As-welded corrosion resistance | Excellent | Good | Excellent |
| Pitting resistance (PRE ~) | 52 | 50 | 60 |
| Relative material cost | Base | +5 to +15% | +20 to +35% |
| ASTM plate standard | B575 | B575 | B575 |
When to choose C4 plate:
Equipment will be welded and placed into service without post-weld heat treatment
Service temperature exceeds 650°C for extended periods
Primary corrosive media is hydrochloric or phosphoric acid
Cost optimization is important and the service conditions do not require C22's higher oxidizing acid resistance
Fabricated components require extensive forming (C4's high ductility is advantageous)
When to choose C276 plate:
Broadest coverage across mixed acid environments at moderate temperatures (below 500°C)
Reducing acids combined with chloride contamination
General chemical service with unpredictable chemistry variations
When to choose C22 plate:
Strongly oxidizing environments (concentrated HNO₃, ferric chloride, hot HNO₃+HF mixtures)
Alternating oxidizing/reducing conditions (flue gas desulfurization, pickling lines)
Maximum pitting resistance in high-chloride oxidizing media is the primary requirement
Many engineers first evaluate 316L alloy before considering C4. Here is when upgrading is justified:
| Criterion | 316L Stainless | Hastelloy C4 |
|---|---|---|
| Max service temperature (corrosive) | ~300°C | ~1040°C |
| Resistance to HCl | Poor (rapid attack) | Excellent |
| Resistance to chloride pitting | Moderate (pits at > ~50°C in seawater) | Excellent |
| Resistance to stress corrosion cracking | Susceptible in hot chloride solutions | Resistant |
| As-welded corrosion resistance | Good (with L-grade control) | Excellent |
| Cost per kg (approximate ratio) | 1× | 8–12× |
The cost difference is substantial. The business case for C4 over 316L is strongest when: replacement cost and downtime from corrosion failure is high, the service life required is long (10+ years), or safety regulations mandate CRA (corrosion-resistant alloy) materials for hazardous media.
| Standard System | Designation |
|---|---|
| Trade name (Haynes International) | Hastelloy C4 |
| UNS | N06455 |
| DIN / EN (Werkstoff Nr.) | 2.4610 |
| GB/T (China National Standard) | NS335 |
| ISO | NiCr16Mo16Ti |
| JIS | NW 4405 |
| AFNOR (France) | NC17D16 |
Chemical Processing:Pressure vessel shells and heads for HCl, H₂SO₄, and H₃PO₄ service. Reactor vessel liners and internals. Heat exchanger shell plates in acid service. Expansion joint and bellows fabrication from formed plate.
Pharmaceutical Manufacturing:Reactor vessel walls and agitator assemblies. Distillation column trays and packed tower internals. Solvent recovery system components. Any equipment requiring weld integrity without post-weld annealing.
Nuclear Fuel Reprocessing:Dissolution vessel linings and covers. Evaporator shell plates in boiling nitric acid service. Transfer equipment for radioactive solutions.
Flue Gas Desulfurization (FGD):Absorber tower shell plates. Recirculation pump casing plates. Spray header fabrication plate.
Marine and Offshore:Heat exchanger shell plates in seawater cooling circuits. Desalination plant component plates. Offshore chemical injection system vessels.
All Hastelloy C4 plates and sheets supplied by JN Alloy comply with:
| Document | Scope |
|---|---|
| ASTM B575 / ASME SB575 | Low-Carbon Nickel-Chromium-Molybdenum Alloy Plate, Sheet, and Strip |
| ASTM B906 | General Requirements for Flat-Rolled Nickel and Nickel Alloy Plate, Sheet, and Strip |
| ASME Section IX | Welding procedure and welder qualification (for fabricated items) |
| NACE MR0175 / ISO 15156 | Sour gas service material qualification |
| EN 10204 3.1 / 3.2 | Material test report certification options |
Every plate is supplied with a full Mill Test Report (MTR) covering: chemical composition, mechanical properties (tensile, yield, elongation), hardness, heat treatment records, and dimensional inspection. PMI (Positive Material Identification) by XRF is available on request.
Q: Can Hastelloy C4 plate be used in the as-welded condition without post-weld annealing?
Yes. This is one of C4's most important practical advantages over other C-family alloys. The combination of ultra-low carbon (≤0.015%) and the absence of tungsten prevents carbide and secondary phase precipitation at grain boundaries during welding. For most applications, welded C4 assemblies can be placed directly into corrosive service without any post-weld heat treatment, which significantly reduces fabrication cost and lead time on large welded vessels.
Q: What is the maximum service temperature for Hastelloy C4 plate?
Hastelloy C4 maintains its corrosion resistance and mechanical properties in continuous service up to approximately 1040°C (1900°F) in oxidizing environments. In strongly reducing or sulfur-bearing high-temperature atmospheres, the practical service limit is lower — typically 700–800°C — and should be evaluated against the specific gas composition.
Q: How does Hastelloy C4 plate compare to 316L stainless steel in HCl service?
In 10% hydrochloric acid at 50°C, Hastelloy C4 shows a corrosion rate below 0.05 mm/year. Under identical conditions, 316L stainless steel typically corrodes at rates exceeding 2.0 mm/year — more than 40 times faster. For any application involving hydrochloric acid above trace concentrations, Hastelloy C4 (or another C-family alloy) is the appropriate material; 316L stainless steel is not suitable for HCl service.
Q: What surface finishes are available for Hastelloy C4 plate?
We supply C4 plate in No. 1 (hot-rolled annealed and pickled), 2B (cold-rolled, bright annealed), No. 4 (brushed), and BA (bright annealed) finishes. For chemical process equipment, No. 1 is standard for plate over 4.8 mm thickness. For pharmaceutical reactors or food-contact applications, No. 4 or 2B is typically specified to minimize crevice corrosion risk from surface roughness.
Q: What certifications come with your Hastelloy C4 plates?
All material is supplied with EN 10204 3.1 Mill Test Reports as standard, covering chemical composition, mechanical properties, and heat treatment records. EN 10204 3.2 (third-party witness inspection) is available on request. We also support SGS, Bureau Veritas, and TÜV inspection. NACE MR0175 / ISO 15156 compliance documentation is available for sour service applications.
Q: What is the minimum order quantity for Hastelloy C4 plate?
We supply from single plates for maintenance and repair purposes through to full project tonnage. Contact our technical sales team with your required dimensions, thickness, and quantity for a precise quotation and lead time.
Q: Is Hastelloy C4 plate magnetic?
No. Hastelloy C4 is a fully austenitic alloy and is non-magnetic in all standard mill conditions.
JN Alloy maintains stock of Hastelloy C4 plate in common thicknesses. For project quantities, custom dimensions, or cut-to-size requirements, contact our technical team with the following information:
Required thickness(es) and tolerance.
Width and length (or specify "cut-to-size from standard mill sheet").
Surface finish required.
Applicable standard (ASTM B575 or ASME SB575).
Certification requirements (3.1, 3.2, third-party).
Required quantity and delivery schedule.
Email: info@jnalloy.com | WhatsApp: +86 19339900211
