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(%):