Inconel625 (N06625) nickel-based deformed high-temperature alloy
1. Inconel625 organizational structure
1.1 Inconel625 phase transition temperature
1.2 Inconel625 time-temperature-structure transformation curve
1.3 Inconel625 alloy structure The structure of the alloy in the solid solution state is an austenite matrix and a small amount of TiN, NbC, and M6C phases. After long-term aging at 650 to 900°C, the precipitated phases are γ", δ, M23C6, and M6C .Long term at 650~700℃
After aging, γ" is mainly precipitated, which significantly improves the room temperature and high temperature strength of the alloy, while the plasticity decreases, but still maintains a high level. After aging at 780~850℃, δ phase mainly precipitates, and although the strength is improved, the plasticity of the alloy decreases. After aging at 900°C, there is only a small amount of precipitated phase, so the mechanical properties are similar to those in the solid solution state. The δ phase is an orthorhombic structure flake Ni3Nb, and exists in the form of acicular Widmansite structure.
2. Inconel625 process performance and requirements
2.1 Inconel625 formability The alloy has good cold and hot formability. The heating temperature for steel ingot forging is 1120°C, the starting forging temperature is not lower than 1030°C, and the stopping temperature is not lower than 930°C; during die forging, the final deformation should not be less than 15% to 20%. The rolling heating temperature is 1120 ~ 1160 ℃, the rolling start temperature is not less than 1050 ℃, the rolling stop temperature is not less than 930 ℃, the deformation of the thin cold rolled semi-finished product is 25% ~ 30%, and the deformation of the finished product is not less than 30%. The quenching temperature of intermediate and finished products is 1100℃±10℃[1,8].
2.2 Welding performance of Inconel625 The alloy has good welding performance. It can be used for argon arc welding with tungsten electrode or this alloy as additive under protective atmosphere. Brazing connection and resistance seam welding can also be used.
2.3 Heat treatment process of Inconel625 parts: stress relief: 900℃; annealing: 930~1040℃, 1h; solution treatment: 1090~1200℃, air cooling or water cooling. When the alloy is operated at no higher than 650°C, hot rolled, cold rolled or annealed materials can be used as required. When the working temperature is above 650°C, the annealing process can be used for parts that require better fatigue performance and tensile strength, and the solution treatment can be used for parts that require better creep and durability properties.
2.4 Inconel625 surface treatment process: When removing the oxide scale on the alloy surface, it is first washed with alkali and then pickled in nitric acid-hydrofluoric acid-aqueous solution.
2.5 Inconel625 cutting and grinding performance Carbide or high-speed steel cutting tools should be used. The cutting tools used should have a positive rake angle. Water-based coolant is recommended for high-speed cutting, and thicker coolant is recommended for low-speed cutting.
