Alloy 625 is a nickel-chromium-molybdenum alloy known for its great strength, hardness, and corrosion resistance. The stiffening action of molybdenum and niobium on the nickel-chromium matrix gives alloy 625 its strength. Although the alloy was designed for high-temperature strength, its heavily alloyed composition also offers excellent general corrosion resistance.
Corrosion Resistance
At high temperatures, Alloy 625 offers strong resistance to oxidation and scale. Scaling resistance becomes a significant factor in service at around 1800 °F. Under cyclic heating and cooling circumstances, it outperforms several other high-temperature alloys. Alloy 625 can survive a wide range of harsh corrosive conditions because of the mix of alloying elements. Mild settings, such as fresh and seawater, neutral pH environments, and alkaline environments, have essentially little attack. This alloy’s chromium concentration leads to improved resistance to oxidizing conditions. Alloy 625 is highly resistant to pitting and crevice corrosion because of its high molybdenum content.
Heat Treatment and Fabrication
Cold and hot working techniques can be used to create Alloy 625. Because Alloy 625 resists deformation at high working temperatures, larger stresses are needed to produce the material. Temperatures ranging from 1700 °C to 2150 °F should be used for hot forming. Cold working causes the material to work-harden faster than standard austenitic stainless steel.
Alloy 625 is heat-treated in three ways:
- Solution annealing at 2000/2200°F with air quenching or faster, annealing at 1600/1900°F with air quenching or faster, and stress-relieving at 1100/1500°F with air quenching
- Solution-annealed (grade 2) material is typically utilized in situations above 1500°F where creep resistance is required.
- Soft-annealed material (grade 1) is often utilized for lower temperatures since it has the best tensile and rupture qualities.
Application of Inconel 625 plates
- Extraction of Oil and Gas: Because of its strong temperature resistance and oxidation resistance, Inconel is suited for use in the oil and gas extraction sectors. The oil and gas industries require a superalloy metal, such as Inconel, that can tolerate harsh conditions and corrosive gases. The superalloy Inconel 625 is particularly beneficial for natural gas processing systems. Due to its exceptionally high thermal fatigue strength and oxidation resistance, Inconel 625 Plates are frequently used for the separation of extracted fluids or inline steel transfer pipework.
- Applications for Heat Treatment: Inconel is well-known for its resistance to severe temperatures and the ability to maintain adequate tensile strength at high temperatures to support modest loads (Inconel 625 retains 13.3 KSI tensile strength at 2,000°F). As a result, Inconel is an excellent material for baskets in heat-treating applications. When carrying components during a strong heat treat application, a basket composed of a superalloy like Inconel will not lose form as quickly as other stainless-steel alloys.
- Rapid Temperature Variations: Some manufacturing processes may rapidly alternate between high and low temperatures. Most Inconel alloys have exceptional oxidation resistance at both high and low temperatures, allowing a single Inconel basket to be used in operations with temperatures ranging from near-cryogenic lows to heat treatment highs.
- Applications in Saltwater: Because of its exceptional resistance to sodium chloride (salt) across a wide range of temperatures, Inconel is frequently utilized in maritime applications. As a result, Inconel can be perfect for a part washing basket in operations that employ salt or in manufacturing settings near the ocean. Some stainless-steel alloys, on the other hand, have great seawater resistance. In general, this superalloy would be far more beneficial than grade 316 stainless steel if severe temperatures of over 1,000 °F were also a problem. At high temperatures, Inconel would preserve its oxidation resistance better than 316 SS.
