Alloy C276 Round Rod ASTM EN GB Standard
Alloy C276 (UNS N10276, Werkstoff Nr. 2.4819) is a
nickel-molybdenum-chromium-tungsten alloy renowned for its
exceptional corrosion resistance in the harshest industrial
environments, particularly against oxidizing and reducing media.
Hot-rolled Alloy C276 round bars are widely used in critical
applications where durability, chemical stability, and mechanical
strength are non-negotiable. Below is a comprehensive overview of
its parameters, properties, production process, standards,
equivalent grades, and applications.
1. Chemical Composition (Key Parameters)
The superior performance of Alloy C276 stems from its precisely
controlled chemical composition, which balances corrosion
resistance and mechanical properties. The typical composition (per
ASTM B574) is as follows:
| Element | Content Range (%) | Primary Function |
|---|
| Nickel (Ni) | ≥ 57 | Base metal; provides structural stability and resistance to
chloride stress corrosion cracking (SCC) |
| Chromium (Cr) | 14.5 - 16.5 | Enhances resistance to oxidizing media (e.g., nitric acid, air, and
seawater) |
| Molybdenum (Mo) | 15.0 - 17.0 | Improves resistance to reducing media (e.g., sulfuric acid,
hydrochloric acid) |
| Tungsten (W) | 3.0 - 4.5 | Boosts resistance to pitting and crevice corrosion; strengthens the
alloy |
| Iron (Fe) | ≤ 5.0 | Reduces alloy cost while maintaining ductility |
| Carbon (C) | ≤ 0.01 | Minimizes carbide precipitation (avoids intergranular corrosion in
high-temperature service) |
| Silicon (Si) | ≤ 0.08 | Controls oxidation during melting; limits impurity-induced
brittleness |
| Manganese (Mn) | ≤ 1.0 | Enhances hot workability during rolling |
| Phosphorus (P) | ≤ 0.04 | Reduces embrittlement risks |
| Sulfur (S) | ≤ 0.03 | Minimizes cracking during fabrication |
2. Mechanical & Physical Properties
Hot-rolled Alloy C276 round bars exhibit a unique combination of
high strength, ductility, and thermal stability, making them
suitable for both ambient and elevated-temperature applications.
2.1 Mechanical Properties (Hot-Rolled Condition, per ASTM B574)
| Property | Test Standard | Value (Typical) | Unit |
|---|
| Tensile Strength (UTS) | ASTM E8 | ≥ 795 | MPa |
| Yield Strength (0.2% Offset) | ASTM E8 | ≥ 310 | MPa |
| Elongation (in 50 mm) | ASTM E8 | ≥ 40 | % |
| Hardness (Brinell) | ASTM E10 | ≤ 210 | HB |
Note: Post-heat treatment (e.g., solution annealing at 1120–1150°C
followed by rapid quenching) can further optimize toughness and
corrosion resistance by eliminating residual stresses.
2.2 Physical Properties
| Property | Value | Unit |
|---|
| Density | 8.89 | g/cm³ |
| Melting Range | 1325–1370 | °C |
| Thermal Conductivity (25°C) | 10.8 | W/(m·K) |
| Coefficient of Thermal Expansion (20–100°C) | 12.4 × 10⁻⁶ | /°C |
| Electrical Resistivity (25°C) | 1.37 × 10⁻⁶ | Ω·m |
3. Production Process of Hot-Rolled Alloy C276 Round Bars
The manufacturing process of hot-rolled Alloy C276 round bars
adheres to strict quality controls to ensure consistency and
performance. Key steps include:
Raw Material Melting & Casting
- High-purity nickel, molybdenum, chromium, and tungsten are melted
in an electric arc furnace (EAF) or vacuum induction melting (VIM)
furnace to avoid contamination.
- The molten alloy is cast into cylindrical ingots (billets) via
continuous casting or static casting, with diameters ranging from
150 mm to 500 mm.
Homogenization Annealing
- Billets are heated to 1050–1100°C and held for 8–12 hours to
eliminate chemical segregation and improve workability.
Hot Rolling
- Annealed billets are heated to 1000–1100°C (the alloy’s optimal
hot-working temperature range) and passed through a series of
rolling mills.
- The billets are gradually reduced in diameter to form round bars of
the desired size (common diameters: 10 mm–300 mm). Hot rolling
enhances grain structure and mechanical strength.
Solution Annealing & Quenching
- After rolling, bars undergo solution annealing at 1120–1150°C for
30–60 minutes, then rapidly quenched in water or air. This step
dissolves carbides and precipitates, restoring maximum corrosion
resistance.
Surface Treatment
- Bars are descaled (via pickling with nitric-hydrofluoric acid) to
remove oxide layers formed during rolling.
- Optional finishing processes: grinding, polishing, or turning to
achieve precise dimensional tolerance (e.g., h9/h10) and surface
roughness (Ra ≤ 6.3 μm).
Quality Inspection
- Non-destructive testing (NDT): Ultrasonic testing (UT) for internal
defects, magnetic particle testing (MT) for surface cracks.
- Chemical composition analysis (via 光谱 analysis, OES), mechanical
property testing (tensile, hardness), and dimensional verification.
4. International Standards
Alloy C276 round bars are manufactured and inspected in compliance
with global standards to ensure interoperability across industries.
The most widely recognized standards are:
| Standard System | Standard Number | Specification Scope |
|---|
| ASTM (USA) | ASTM B574 | Standard Specification for Nickel-Chromium-Molybdenum-Tungsten
Alloy (UNS N10276) Bars and Rods |
| EN (Europe) | EN 10088-3 | Stainless Steels and Heat-Resisting Steels – Part 3: Wrought
Products (Alloy 2.4819) |
| GB (China) | GB/T 2054 | Nickel and Nickel Alloy Bars and Rods (Equivalent grade: N06276) |
| ISO | ISO 6208 | Nickel and Nickel Alloy Rods and Bars (General requirements for
Alloy C276) |
5. Equivalent Grades
Alloy C276 is standardized under different designations worldwide.
These grades have nearly identical chemical composition and
performance, ensuring compatibility in cross-border projects:
| Standard System | Grade Designation | Corresponding Alloy |
|---|
| UNS (USA) | UNS N10276 | Alloy C276 |
| DIN/EN (Europe) | Werkstoff 2.4819 | Alloy C276 |
| GB (China) | N06276 | Alloy C276 |
| JIS (Japan) | NW2276 | Alloy C276 |
| BS (UK) | NA 21 | Alloy C276 |
6. Applications
Alloy C276 round bars are favored in industries requiring superior
corrosion resistance and mechanical reliability under extreme
conditions. Typical applications include:
Chemical Processing Industry
- Components for sulfuric acid production (reactors, heat
exchangers), hydrochloric acid handling (pumps, valves), and
pharmaceutical synthesis (reaction vessels).
Oil & Gas Industry
- Downhole tools, wellhead components, and pipeline parts for
offshore and sour gas environments (resists H₂S and
chloride-induced SCC).
Environmental Engineering
- Flue gas desulfurization (FGD) systems, wastewater treatment
equipment, and incinerator parts (withstands acidic fumes and high
temperatures).
Aerospace & Defense
- Engine components, rocket nozzles, and military hardware (tolerates
high-temperature oxidation and chemical exposure).
Other High-Performance Sectors
- Nuclear power plant components (resists radiation-induced
degradation), marine engineering (seawater-resistant fasteners),
and semiconductor manufacturing equipment (high-purity
requirements).
Monel 400 Alloy Sheet Plate UNS N04400 Nickel Alloy ASTM B127
