K418B overview
K418B is a modified nickel-based cast superalloy of K418. Compared with K418 alloy, its content of carbon and titanium is lower, its room temperature plasticity and impact toughness are obviously improved, and its microstructure stability is better. The alloy composition is relatively simple, does not contain cobalt, and is relatively cheap. It has high creep strength, thermal fatigue and oxidation resistance below 900ºC. Good casting performance, suitable for making gas turbine guide vanes and rotor blades working below 900 ºC, as well as integral casting turbines, and can also be used as other large castings with large cross-sections for high temperature.
K418B technical standard
HB 7239-1995 "K418B Alloy Ingot"
Chemical composition of K418B
Carbon C (%): 0.03~0.07
Chromium Cr(%): 11.00~13.00
Molybdenum Mo(%): 3.80~5.20
Nickel Ni(%): Allowance
Cobalt Co(%): ≤1.00
Tungsten W(%): -
Aluminum AI(%): 5.50~6.50
Niobium Nb (%): 1.50~2.50
Titanium Ti(%): 0.40~1.00
Iron Fe(%): ≤0.5
Copper Cu(%): ≤0.5
Silicon Si(%): ≤0.5
Manganese Mn(%): ≤0.25
Phosphorus P(%): ≤0.015
Sulfur S(%): ≤0.015
Boron B (%): 0.005~0.015
Zirconium Zr(%): 0.05~0.15
K418B heat treatment system
Use as-cast, or 1180ºC, 2h, air-cooled.
K418B Variety Specifications and Supply Status
Round bar-shaped master alloy ingots, supplied as-cast.
K418B application overview and special requirements
The alloy has been used in the rotor blade of a free turbine of a turboshaft engine. The working temperature is about 850°C, the speed is 38000r/min, and the service life is 2500-3000h. In addition, it has also been successfully applied to new turboprop aero-engines. The INC0713LC alloy, which is similar to this alloy, is widely used abroad, such as 2-6 working blades on AFF-3 turbofan engines; turbine guides, integral rotors, and rotors on TPF-31 and T-76 turbo-turboprop engines. Blades; WR24-7 unmanned aircraft engine turbine disks; also used in the integral casting turbines of long-term power generation gas turbines. The alloy must have a protective surface coating for long-term use in the marine environment.
K418B supply performance and requirements
(1) Formability
The casting performance is good, and the investment casting method can be used to cast blades with a wall thickness of less than 1mm and an integral turbine rotor with a diameter of 130mm, and the alloy has a small tendency of hot cracking.
(2) Welding performance
Electron beam welding, argon arc welding, isothermal solidification diffusion welding and friction drying can be performed.
(3) Heat treatment process of parts
Castings are usually subject to internal stress relief annealing, the system is: 930-950 ºC, 2h, air cooling.
(4) Surface treatment process
Aluminized or chrome-aluminum co-infiltration can be performed.
(5) Cutting and grinding performance
The alloy is easier to machine. The tool material should be cemented carbide.
The above is the introduction of K418B (K18B) nickel-based casting superalloy materials
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