1. Core Specifications (140-350mm Forged Round Bar)
The dimensions and key parameters of this Hastelloy C276 round bar are optimized for heavy-duty industrial use, balancing strength and machinability.
| Parameter | Specification |
| Product Form | Forged round bar (hot-forged for enhanced density and grain structure) |
| Diameter Range | 140mm – 350mm (forged to tight dimensional tolerance; custom diameters available on request) |
| Length | Custom cutting available (any length, e.g., 100mm, 500mm, 1000mm, up to 6000mm; no minimum length restriction) |
| Forging Process | Hot forging (temperature range: 1150°C – 1230°C) followed by annealing for stress relief |
| Surface Finish | Forged surface (as-forged: slight oxidation layer) or pickled surface (optional, for corrosion resistance enhancement) |
| Tolerance (Diameter) | ASTM A480/A480M: ±0.5mm for diameters ≤200mm; ±0.8mm for diameters >200mm |
| Tolerance (Length) | Custom-cut length tolerance: ±1mm (standard) or ±0.5mm (precision cutting) |
2. Chemical Composition
Hastelloy C276’s exceptional corrosion resistance stems from its precisely balanced alloying elements, with low carbon and silicon content to prevent carbide precipitation (a common cause of intergranular corrosion).
| Element | Content Range (%) | Key Function |
| Nickel (Ni) | 56.0 min | Base metal; provides ductility and resistance to reducing environments |
| Molybdenum (Mo) | 15.0 – 17.0 | Enhances resistance to pitting, crevice corrosion, and sulfuric acid |
| Chromium (Cr) | 14.5 – 16.5 | Boosts oxidation resistance and resistance to oxidizing acids (e.g., nitric acid) |
| Iron (Fe) | 4.0 – 7.0 | Improves mechanical strength and forging workability |
| Tungsten (W) | 3.0 – 4.5 | Synergizes with Mo to enhance pitting corrosion resistance in chloride-rich media |
| Cobalt (Co) | 2.5 max | Controls alloy ductility and reduces brittleness |
| Carbon (C) | 0.01 max | Minimizes carbide formation (critical for weldability) |
| Silicon (Si) | 0.08 max | Prevents oxidation during high-temperature processing |
| Phosphorus (P) | 0.04 max | Limits impurities to avoid brittleness |
| Sulfur (S) | 0.03 max | Reduces hot cracking risk during forging and welding |
3. Mechanical & Corrosion Performance
This alloy excels in both mechanical strength and corrosion resistance, making it suitable for load-bearing components in aggressive environments.
3.1 Mechanical Properties (Annealed Condition)
| Property | Value (Typical) |
| Tensile Strength (σb) | ≥690 MPa |
| Yield Strength (σ0.2) | ≥310 MPa |
| Elongation (δ) | ≥40% (in 50mm gauge length) |
| Hardness (HB) | ≤210 |
| Impact Toughness (Charpy V-notch) | ≥100 J (at room temperature) |
| Maximum Service Temperature | 1093°C (short-term); 649°C (long-term, for continuous oxidation resistance) |
3.2 Corrosion Resistance
Hastelloy C276 is renowned as one of the most corrosion-resistant alloys globally, withstanding:
- Reducing acids: Sulfuric acid (up to 90% concentration), hydrochloric acid (dilute to moderate concentrations), and phosphoric acid.
- Oxidizing acids: Nitric acid (dilute), chromic acid, and mixed acids (e.g., acid rain, chemical process streams).
- Chloride-rich media: Seawater, brines, and chloride solutions (resists pitting and crevice corrosion—critical for marine and offshore applications).
- High-temperature environments: Resists oxidation and sulfidation in flue gases, incinerators, and petrochemical reactors.
Key Advantage: Unlike many stainless steels, it does not require post-weld heat treatment (PWHT) to maintain corrosion resistance, simplifying fabrication.
4. Manufacturing & Quality Standards
Hastelloy C276 forged round bars adhere to strict international standards to ensure consistency and reliability.
| Standard Category | Relevant Standards |
| Chemical Composition | ASTM B574, ASME SB574, DIN EN 10095 |
| Forging & Dimensional | ASTM A480/A480M (flatness/tolerance), ISO 898-6 (forging quality) |
| Mechanical Properties | ASTM B574, ASME SB574, BS 3074 (Part NA16) |
| Testing Requirements | - Non-destructive testing (NDT): Ultrasonic testing (UT) per ASTM A609 (100% coverage for defects)
- Chemical analysis: Spectrometric testing
- Mechanical testing: Tensile, hardness, and impact tests (per lot) |
| Surface Quality | ASTM A788 (for pickled surface) or ASTM A967 (passivation, optional) |
5. Equivalent Grades
Hastelloy C276 is marketed under different designations globally; these grades are chemically and performance-equivalent:
| Standard/Region | Equivalent Grade |
| ASTM/ASME (USA) | UNS N10276, Alloy C276 |
| DIN EN (Europe) | W. Nr. 2.4819 |
| BS (UK) | NA16 |
| JIS (Japan) | NW 276 |
| GB (China) | NS334 |
| ISO | NiMo16Cr15W (ISO 15156-3) |
Note: While these grades are interchangeable in most applications, always confirm compliance with project-specific standards (e.g., ASME BPVC for pressure vessels).
6. Applications
The 140-350mm diameter Hastelloy C276 forged round bar—with its custom length option—is ideal for large, heavy-duty components requiring both strength and corrosion resistance. Key applications include:
- Petrochemical & Refining: Reactors, pressure vessels, and heat exchanger tubes (resists sulfuric acid and hydrogen sulfide).
- Marine & Offshore: Propeller shafts, valve stems, and seawater handling components (withstands seawater corrosion and biofouling).
- Chemical Processing: Pumps, valves, and agitators for acid production (e.g., sulfuric, hydrochloric, and nitric acid plants).
- Waste Incineration: Furnace liners and flue gas ducts (resists high-temperature oxidation and acidic ash).
- Aerospace & Defense: Engine components and rocket nozzles (tolerates high temperatures and aggressive fuels).
7. Customization & Value-Added Services
To meet diverse project needs, the following customizations are available for this Hastelloy C276 round bar:
- Length Cutting: Any length (from short segments to full-length bars) via precision sawing or plasma cutting (no minimum order quantity for standard diameters).
- Surface Treatment: Pickling, passivation, or grinding (for tight surface roughness requirements, e.g., Ra ≤0.8μm).
- Heat Treatment: Annealing (standard), solution annealing, or stress relieving (per customer specifications).
- Certifications: Mill test certificates (MTC) per EN 10204 (3.1B or 3.2), NACE MR0175/ISO 15156 compliance (for sour gas applications), and FDA approval (for food-grade chemical processing).
