ASTM B425
ASTM B425 Basic Info
ASTM B425 outlines the composition and importance of nickel-iron-chromium-molybdenum-copper alloys, specifically UNS N08825, N08221, and N06845, in the form of plate, sheet, and strip. These alloys are designed to withstand extreme conditions such as high temperatures and corrosive environments encountered in industries like chemical processing, aerospace, and marine engineering.
Characteristics of ASTM B425
- High Corrosion Resistance: ASTM B425 alloys exhibit exceptional resistance to corrosion in a variety of harsh environments, including those with acids, alkalis, and chloride solutions.
- High Temperature Resistance: These alloys maintain their mechanical properties at elevated temperatures, making them suitable for use in high-temperature applications such as heat exchangers and furnace components.
- Excellent Strength and Toughness: ASTM B425 alloys offer a combination of high strength and toughness, making them suitable for demanding structural applications.
ASTM B425 Data Sheet
Steel Grade
Dimensions and Tol.
Equivalent Steel Grades
Chemical Composition
Mechanical Properties
Fabrication and Welding
Steel Grade
UNS N08825:
Nickel-Iron-Chromium-Molybdenum-Copper Alloy (Incoloy 825)
UNS N08221:
Nickel-Iron-Chromium-Molybdenum-Copper Alloy (Alloy 825)
Dimensions and Tol.
Round Bar:
Width or Diameter: 0.1875 – 6.000 inches
Tolerances: Diameter ±0.004 inches
Hex Bar:
Width or Diameter: 0.250 – 1.500 inches
Tolerances: Across Flats ±0.010 inches
Square Bar:
Width or Diameter: 0.1875 – 2.500 inches
Tolerances: Side ±0.010 inches
Equivalent Steel Grades
UNS N08825:
Germany (DIN): DIN 2.4858, DIN 2.4859
Japan (JIS): JIS NCF825, JIS NCF825A
China (GB/T): GB/T NS1402, GB/T NS1403
United Kingdom (BS): BS NA16, BS NA16T
Chemical Composition
Nickel (Ni): 38.0 – 46.0
Iron (Fe): 22.0 min
Chromium (Cr): 19.5 – 23.5
Molybdenum (Mo): 2.5 – 3.5
Copper (Cu): 1.5 – 3.0
Titanium (Ti): 0.6 – 1.2
Aluminum (Al): 0.2 max
Manganese (Mn): 1.0 max
Silicon (Si): 0.5 max
Carbon (C): 0.05 max
Sulfur (S): 0.03 max
Phosphorus (P): 0.03 max
Mechanical Properties
Tensile Strength:
85 ksi (586 MPa), Annealed
105 ksi (724 MPa), Solution Annealed
Yield Strength (0.2% offset):
35 ksi (241 MPa), Annealed
35 ksi (241 MPa), Solution Annealed
Elongation:
30%, Annealed
30%, Solution Annealed
Fabrication and Welding
Hot Forming:
Temperature range: 1600-2250°F (870-1230°C). Avoid working below 1700°F (927°C). Rapid quench after hot forming.
Cold Forming:
Can be cold formed using standard methods.
Machining:
Use water-based coolant for cutting operations. Avoid sulfur-based oils.
Welding:
Use Inconel filler metal 825 for high-temperature applications. Preheat and post-weld heat treatment may be required.
Avoid working below 1700°F (927°C).
Handling Issues with ASTM B425 Materials
Handling issues with ASTM B425 materials requires a precise understanding of the material’s properties and characteristics. ASTM B425 specifies the requirements for a high-strength, corrosion-resistant nickel-iron-chromium alloy, often used in demanding environments such as chemical processing, marine engineering, and aerospace applications. Here are some common issues that may arise when working with ASTM B425 materials and how to address them:
Corrosion Resistance: While ASTM B425 materials are known for their corrosion resistance, improper handling or exposure to certain environments can still lead to corrosion. It’s crucial to store the material in a dry and controlled environment to prevent corrosion. If corrosion does occur, it may be necessary to clean the surface using approved methods and apply a corrosion-resistant coating.
Machinability Challenges: ASTM B425 materials are known for their high strength, which can pose challenges during machining. Use appropriate cutting tools and techniques designed for high-strength alloys. Carbide tooling is often recommended for its durability. Adequate coolant should be used during machining to dissipate heat and extend tool life.
Weldability: Welding ASTM B425 materials requires careful consideration due to their high nickel content and the potential for cracking. Preheating and post-weld heat treatment may be necessary to reduce the risk of cracking. Using nickel-based welding consumables designed for high-nickel alloys can improve weld quality.
Heat Treatment: ASTM B425 materials can benefit from heat treatment to achieve desired mechanical properties. Follow the specified heat treatment procedures outlined in the ASTM standard. Deviating from these procedures can lead to issues such as reduced strength or hardness.
Surface Finish: Achieving a desired surface finish on ASTM B425 materials can be challenging due to their hardness. Proper tool selection and machining parameters can help achieve the desired surface roughness. Post-machining processes such as grinding or polishing may be necessary for critical applications.
Handling and Storage: ASTM B425 materials should be handled with care to prevent damage. Avoid dropping or mishandling the material, as this can cause surface imperfections or fractures. When not in use, store the material in a clean, dry environment to prevent contamination and maintain its integrity.
By understanding these potential issues and following best practices, such as those outlined in ASTM B425 and other relevant standards, users can mitigate risks and ensure the optimal performance of ASTM B425 materials in their applications.
