Commercial grade: Inconel625 Nickel-based high temperature alloy
United States grade: UNSN06625
Chinese grade: GH3625/GH625
French grade: NC22DNb
German grade: W.Nr.2.4856
Inconel625 (NO6625) High Temperature Alloy Overview
Inconel625 is a solid solution reinforced nickel-based high-temperature alloy with molybdenum and niobium as the main reinforcement elements. It has excellent corrosion resistance and oxidation resistance. Low temperatures to 980℃ have good tensile and fatigue properties and are resistant to stress corrosion in salt spray environments. Therefore, it can be widely used in the manufacturing of aerospace engine parts, aerospace structural parts and chemical equipment. The alloy has good processing and welding properties and can supply a variety of sheets, bars, pipes, wires, strips and forgings.
Material grade: Inconel 625.
2 Similar brands of Inconel625: gh3625 (GH625) (China), unsno6625 (US), nc22dnb (France), 2.4856 (Germany).
Chemical composition
| C≤ | Si≤ | Mn≤ | P≤ | S≤ | Cr≥ | Ni≥ | Mo≥ | Cu≤ |
| 0.10 | 0.50 | 0.50 | 0.015 | 0.015 | 20.0-23.0 | margin | - | 0.07 |
| other | N≤ | Al≤ | Ti≤ | Fe≤ | Co≤ | V≤ | W≤ | Nb≤ |
| - | 0.40 | 0.40 | 5.00 | 1.00 | - | - | 3.15-4.15 |
Heat treatment system: air-cooled or water-cooled at 950~1030℃; or air-cooled or water-cooled solution treatment at 1090~1200℃. Plate: 950~1030℃, air-cooled; or 1090~1200℃, air-cooled. Pipe: Recommended annealing temperature: 960~1030℃, air-cooled or water-cooled.
Variety specifications and supply status: can supply d25-80mm bars, δ0.8-10.5mm plates, d6-40mm seamless (welded) pipes. The bars are delivered in a turning or polished state without heat treatment; the plates are supplied after solid solution and finishing; the pipelines are supplied after solid solution and pickling (or bright annealing).
Smelting and casting process: Alloys are produced using vacuum induction furnace smelting + electroslag remelting or vacuum induction furnace + vacuum arc remelting process.
Application overview and special requirements: This alloy has been used to manufacture engine case, guide vane, installation edge, cylinder, fuel manifold and other parts, and has passed actual application inspection. The operating temperature is 950℃; after long-term use at 550~700℃, it has a certain aging hardening property, resulting in a reduction in the plasticity of the alloy.
Study on the physical and chemical properties of Inconel625 (NO6625) high temperature alloy
Thermal performance:
(1) The melting temperature range of Inconel625: 1290~1350℃.
(2) Thermal conductivity
(3) Specific heat capacity
(4) Linear expansion coefficient
The density of Inconel 625: ρ=8.44g/cm³.
Electrical properties of Inconel625: alloy resistivity.
| Cyclic oxidation time/h | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 |
| Weight change/% | 980℃ | +0.086 | +0.065 | +0.065 | +0.048 | +0.021 | - | +0.03 | -0.081 |
| 1095℃ | -0.182 | -1.086 | -3.335 | -5.399 | -6.566 | -10.066 | - | - |
Note: Heat the oxidation for 15 minutes and cool for 5 minutes for one cycle.
Corrosion resistance of Inconel625: The alloy has good seawater corrosion resistance, as shown in Table 2-2. This alloy is also resistant to corrosion in various salt solutions. In addition, it has good corrosion resistance to nitric acid and phosphoric acid, and it also has considerable corrosion resistance to hydrochloric acid and low-concentration sulfuric acid heated below the boiling point.
| Test days | Sample Type | Weight loss/g | Local corrosion degree | Test days | Sample Type | Weight loss/g | Local corrosion degree |
| In still sea water | In the flowing seawater (0.61m/s) |
| 180 | Smooth with gaps | 0.05 0.05 | None | 180 | Smooth with gaps | 0.04 0.05 | None |
| 365 | Smooth with gaps | 0.02 0.04 | None | 365 | Smooth with gaps | 0.01 0.02 | None |
Note: Smooth sample refers to a 6.4mm×100mm×300mm round weld flat plate sample annealed at 980°C before welding. A gap-free sample refers to a sample fixed to the center of the plate surface with a 32mm fiber washer.
Mechanical properties of Inconel625 (NO6625) high temperature alloy
Performance specified in Inconel625 technical standard
| variety | Tensile properties | Persistent performance | hardness |
| θ/℃ | σb/MPa | σP0.2/MPa | δ5/% | θ/℃ | σ/MPa | t/h | δ5/% |
| Not less than | Not less than |
| Bar ① | 20 | 830 | 410 | 30 | 815 | 114 | twenty three | 15 | HB≤290 |
| Plate ② | 20 | 830 | 410 | 30 | 815 | 114 | twenty three | 15 | HV≤305 |
| Stick | 20 | 830 | 410 | 30 | Q/3B4078-1992 | - |
| Plate | 20 | 825 | 415 | 30 | Q/3B4077-1992 | - |
| Pipe | 20 | 825 | 415 | 35 | Q/3B4080-1992 | HRC≤25 |
① Standard z9-0105-1990. ② Standards z9-0104-1990 and gjb3317-1998.
Microstructure of Inconel625 (NO6625) high temperature alloy
Phase change temperature of Inconel625
Time-temperature structure transition curve of Inconel625 alloy
Microstructure of Inconel625 alloy: The solid solution structure is an austenite matrix and a small amount of tin, NBC and M6C phases. After long-term aging of 650-900℃, the precipitation phases are γ, δ, M23C6 and M6C; after long-term aging of 650-700℃, the γ" is mainly precipitated, which significantly improves the room temperature and high temperature strength of the alloy, and slightly decreases plasticity, but remains at a high level; after aging of 780-850℃, the precipitation phases are mainly γ, δ, M23C6 and M6C, and the main precipitation phases of the alloy are δ phases. Although the strength has been improved, the plasticity has decreased a lot. After aging at 900°C, there is less precipitate and the mechanical properties are similar to those in solid solution. The δ phase is orthogonal layered ni3nb and exists in needle-shaped Wei's tissue [1,7].
Processing performance and requirements of Inconel625 (NO6625) high temperature alloy
●Inconel625 forming performance
The alloy has good hot and cold forming performance. The heating temperature of the steel ingot forging is 1120℃, the opening forging temperature shall not be less than 1030℃, and the final forging temperature shall not be less than 930℃; during die forging, the final deformation shall not be less than 15%-20%. The rolling heating temperature is 1120-1160℃, the starting temperature is not less than 1050℃, the rolling stop temperature is not less than 930℃, the semi-finished product is deformed by 25%-30%, and the finished product is deformed by no less than 30%. The quenching temperature of intermediate products and finished products is 1100℃±10℃[1,8].
●Soldering performance of Inconel625
The alloy has good welding performance. It can be used for argon arc welding with tungsten electrode or alloy as filler in a protective atmosphere, and can also be used for brazing connections and resistive seam welding.
●Inconel625 parts heat treatment process
Stress elimination: 900℃; Annealing: 930-1040℃, 1H; Solution treatment: 1090-1200℃, air-cooled or water-cooled. When the alloy operates at 650°C, hot rolling, cold rolling or annealed materials can be used as needed. When the working temperature is higher than 650℃, parts with better fatigue performance and tensile strength can adopt annealing process, and parts with better creep and durability can adopt solid solution treatment.
●The surface treatment process of Inconel625 is: first remove the scale on the alloy surface with alkali washing, and then pickle washing in nitric acid-hydrofluoric acid-aqueous solution.
Processing and grinding performance of Inconel625
Carbide or high-speed steel tools should be used. The tool used should have a positive front angle. It is recommended to use water-based coolant for high-speed cutting, and viscous coolant for low-speed cutting.
Inconel625 (NO6625) high temperature alloy varieties, specifications and availability
Category: Danyang Xinmao Alloy can produce various specifications of Inconel625 seamless pipe, Inconel625 steel plate, Inconel625 round steel, Inconel625 forgings, Inconel625 flanges, Inconel625 rings, Inconel625 welded pipes, Inconel625 steel strips, Inconel625 welding wires and supporting welding materials.
Delivery status: Seamless steel pipe: solution + acidic white, length can be fixed; plate: solid solution, pickling, trimming; welded pipe: solid solution acidic white + RT% flaw detection, forging: annealing + turning; bar forging, surface polishing or turning polishing; strip steel cold rolling, solution softening, descaling; wire solution delivery pickling board or straight strip, solid solution straight strip polishing state.