What is the difference between Grade 1 and Grade 2 alloy 625?
Will Inconel 625 rust?
Inconel 625 (UNS N06625) is a nickel-chromium-molybdenum alloy that has excellent corrosion resistance in a variety of corrosive media, especially pitting and crevice corrosion. However, in corrosive environments, Inconel 625 will corrode like other metals.
What is the difference between Grade 1 and Grade 2 alloy 625?
Inconel 625 Grade 2 material is supplied in the solution annealed condition. The main difference between Grade 2 and Grade 1 is the annealing temperature. The minimum annealing temperature for Grade 1 is 1600°F (871°C), while the minimum annealing temperature for Grade 2 is 2000°F (1093°C).
What is the ASTM standard for Inconel 625 pipe?
Inconel 625 welded pipe is a solution hardened high temperature alloy suitable for high temperature and high pressure applications. Pipe produced to ASTM B444 UNS N06625 specification is generally seamless.
What is the difference between Inconel 625 and Inconel 750?
Both Inconel 750 and Inconel 625 are known for their good high temperature performance. However, Inconel 750 has a slightly higher temperature resistance than Inconel 625. Inconel 750 can be used at temperatures up to 760°C (1,400°F), while Inconel 625 can typically be used at temperatures up to 538°C (1,000°F).
Alloy 625 Grade 1 and Grade 2
Two grades of Inconel 625
Inconel 625 is available in two different tempers per ASTM B446:
Grade 1
Inconel 625 Grade 1 is produced in the annealed condition. This is the most commonly stocked version, with a yield strength of 60ksi (414MPa) for bars up to 4 inches (101.6 mm) in diameter and 50ksi (345MPa) for bars up to 10 inches (254 mm) in diameter. Tensile strengths range from 120ksi (827MPa) and 110ksi (758MPa) respectively.
Gnee Steel carries a large stock of solid bars in diameters ranging from 5/8 inch (15.875 mm) to 10 inches (254 mm).
Our inventory is also API 6A CRA and NACE MR0175 / ISO 15156-3 and AMS 5666 certified.
Grade 2
Inconel 625 Grade 2 material is supplied in the solution annealed condition. The primary difference between Grade 2 and Grade 1 is the annealing temperature. The minimum annealing temperature for Grade 1 is 1600°F (871°C), while for Grade 2 it is 2000°F (1093°C). Grade 2 can be given a further stabilization anneal (1800°F / 982°C) to improve resistance to sensitization from exposure to elevated temperatures during service, but this is not required.
After annealing at the higher temperature, mechanical properties are slightly reduced compared to Grade 1 material. Yield strength is reduced from 60ksi/50ksi to 40ksi for all sizes. Likewise, the minimum tensile strength is 100ksi (690MPa).
Since Grade 2 has a higher annealing temperature than Grade 1, our existing Grade 1 stock can be converted to Grade 2 simply by scheduling an additional heat treatment.
Conclusion
625 Grade 2 alloy is a high-performance material used in a wide range of industries with stringent requirements for high-temperature strength, corrosion resistance, and durability. Its ability to withstand extreme temperatures, resist hydrogen embrittlement, and operate reliably in corrosive environments makes it a top choice for applications such as hydrogen dissociator catalyst tubes, power generation, and chemical processing. With these properties, 625 Grade 2 alloy will continue to play a key role in technological advancements in high-demand industries.
