Alloy 625 Round Bar ASTM B446 Inconel Bright Solid Bar

Alloy 625 Round Bar ASTM B446 Inconel Bright Solid Bar

Alloy 625 Round Bar ASTM B446 Inconel Bright Solid Bar

1. Material Composition & Classification

• Alloy 625 (UNS N06625, W.Nr. 2.4856) is an austenitic nickel-chromium-molybdenum-niobium alloy . Its primary constituents include:
  • Nickel (Ni): ≥58% (base matrix).
  • Chromium (Cr): 20–23% for oxidation and corrosion resistance.
  • Molybdenum (Mo): 8–10% and niobium (Nb + Ta): 3.15–4.15% to strengthen the matrix and enhance resistance to pitting, crevice corrosion, and stress-corrosion cracking (SCC) .
  • Minor elements: Iron (Fe ≤5%), manganese (Mn ≤0.5%), silicon (Si ≤0.5%), carbon (C ≤0.1%), and trace amounts of aluminum (Al), titanium (Ti), and cobalt (Co) .
• Classification: A precipitation-hardened nickel-based superalloy, often marketed as Inconel 625 (a trademarked variant) .

2. Manufacturing Standard: ASTM B446

• Chemical composition limits (as outlined above) to ensure consistent metallurgical properties .
• Mechanical requirements:
  • Minimum tensile strength: ≥ 827 MPa (120 ksi).
  • Minimum yield strength (0.2% offset): ≥ 414 MPa (60 ksi).
  • Minimum elongation: ≥ 30% .
  • These values apply to annealed or solution-annealed conditions.
• Heat treatment options specified in ASTM B446:
  • Grade 1 (Annealed): Suitable for general corrosion resistance up to moderate temperatures (e.g., seawater, chemical processing).
  • Grade 2 (Solution Annealed): Optimized for elevated-temperature applications requiring creep and rupture resistance (>1100°F / 593°C) .
• Quality control: Testing for dimensional accuracy, surface finish, and compliance with chemical and mechanical specs.

3. Form & Dimensions

• Shape: Solid, cylindrical round bar with a uniform cross-section.
• Diameter range: Typically 3 mm (0.12 in) to 500 mm (20 in) (custom sizes also available) mangalammetal.com.
• Lengths: Standard lengths of 1–6 meters (3–20 ft), or cut-to-order as required .
• Tolerances: Tight dimensional control, often achieved via cold working (e.g., cold drawing or grinding) to meet ISO H8–H11 tolerances .
• Bright finish:
  • The bright solid bar designation refers to a highly polished, smooth surface finish achieved through processes like cold drawing followed by polishing or grinding .
  • This finish minimizes surface imperfections, enhances corrosion resistance, and facilitates precise machining.
• Surface condition: Free from defects like cracks, laps, or scaling, ensuring reliability in critical applications .

4. Key Properties

• Exceptional Corrosion Resistance:
  • Resistant to general corrosion, pitting, crevice corrosion, and SCC in chloride-ion environments (e.g., seawater, brines) .
  • Immune to attack from mineral acids, organic acids, alkaline solutions, and high-temperature gases .
  • Marine, nuclear, and chemical processing industries benefit from this resistance.
• High-Temperature Performance:
  • Retains strength and integrity from cryogenic temperatures up to 1093°C (2000°F) .
  • Excellent oxidation resistance and creep-rupture strength at elevated temperatures (Grade 2 solution-annealed material is ideal for >593°C / 1100°F) .
• Mechanical Robustness:
  • High tensile and fatigue strength, combined with ductility (≥30% elongation), enabling complex forming and welding without cracking mangalammetal.com.
  • Stiff matrix (due to Mo and Nb additions) provides structural stability under heavy loads .
• Fabrication Characteristics:
  • Good weldability (e.g., GTAW, GMAW) without post-weld heat treatment for most applications .
  • Machinable with proper tooling and cooling (recommended for hardened grades).
• Density: Approximately 8.44 g/cm³ (0.305 lb/in³) .
• Thermal properties: Low thermal expansion coefficient and high modulus of elasticity contribute to dimensional stability .

5. Processing & Finish

• Manufacturing methods:
  • Cast ingots undergo hot working (forging, rolling) to refine grain structure and improve homogeneity.
  • Further cold working (drawing, grinding) reduces diameter and enhances mechanical properties while achieving the bright finish.
  • Optional heat treatments (annealing or solution annealing) optimize for specific service conditions.
• Bright finish process:
  • Cold-drawn bars are polished or ground to remove surface imperfections, resulting in a mirror-like or semi-bright luster.
  • This finish minimizes surface roughness (e.g., Ra ≤0.8–1.6 μm), which is critical for preventing debris accumulation or corrosion initiation.

6. Applications

• Marine engineering: Propeller shafts, seawater piping, offshore platforms, and chemical-resistant fasteners .
• Oil & gas: Downhole tools, subsea equipment, and high-pressure/high-temperature pipelines (resistant to sour gas and H₂S) .
• Chemical processing: Reactors, valves, pumps, and heat exchangers handling corrosive fluids or acids .
• Aerospace & power generation: Combustion chambers, exhaust systems, and turbine components exposed to extreme heat and oxidation mangalammetal.com.
• Nuclear industry: Fuel element spacers, containment vessels, and components requiring resistance to radiation and corrosive coolants .
• General engineering: High-strength fasteners, instrumentation parts, and structural components in harsh environments.

The Alloy 625 Round Bar ASTM B446 Bright Solid Bar is a pinnacle of nickel-based alloy engineering, offering unmatched resistance to corrosion, oxidation, and high-temperature degradation while maintaining robust mechanical properties. Its bright finish and dimensional precision make it suitable for applications where reliability, aesthetics, and long-term performance are non-negotiable. Whether deployed in offshore rigs, chemical plants, or aerospace systems, this barstock delivers enduring value in the world’s most challenging environments.

Chemical Composition(%):

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