Common types

1. GH4169 high temperature alloy

GH4169 alloy is a nickel-chromium-iron-based high-temperature alloy. GH4169 alloy is a nickel-based deformed high-temperature alloy. Nickel-based alloys are one of the most complex alloys. It is widely used to manufacture various high temperature parts. At the same time, it is also the most eye-catching alloy among all high-temperature alloys. Its relative service temperature is also the highest among all common alloy series. The proportion of this alloy in advanced aircraft engines is more than 50%.

GH4169 alloy was successfully developed by Eiselstein of Huntington Branch of the International Nickel Corporation. It was publicly introduced in 1995 and an age-hardening nickel-chromium-iron based deformation alloy. The alloy is a kind of nickel-based deformed superalloy with body-centered cubic g' and face-centered cubic g'phase as precipitation strengthening. It has high tensile strength, yield strength and good plasticity below 650℃, and has good corrosion resistance. , Radiation resistance, fatigue, fracture toughness and other comprehensive properties, as well as satisfactory welding and post-weld forming properties, etc. The alloy has stable structure and performance in a wide temperature range of -253 to 650 ℃, and becomes the use under deep cold and high temperature conditions A wide range of superalloys. Due to the good comprehensive performance of GH4169, it is widely used in the compressor discs, compressor shafts, compressor blades, turbine discs, turbine shafts, casings, fasteners and other structural parts and plates of aero engines Welding parts, etc.

Our country began to develop GH4169 alloy in the 1970s, which is mainly used in discs and has a relatively short use time. Therefore, the double process of vacuum induction and electroslag remelting is adopted. It began to be applied in the aviation field in the 1980s. Improving and improving the quality of materials and improving the overall performance and reliability of alloys have become the main research directions. The current main research directions of GH4169 alloy are:

(1) Improve the smelting process, quantify the smelting parameters, realize the stable operation of the program, make the alloy microstructure more uniform, so as to obtain excellent yield and fatigue strength, anti-crack growth and crack arrest ability, and improve low-cycle fatigue strength;

(2) Improve the heat treatment process. The heat treatment process cannot well eliminate the segregation in the center of the steel ingot, so it has an adverse effect on the uniformity of the structure. Therefore, using a reasonable homogenization annealing process to obtain fine-grained blanks has become one of the main research directions;

(3) Improve the use design. Since the working temperature of GH4169 cannot be higher than 650℃, the cooling of parts should be strengthened to give full play to the high-performance and low-cost advantages of this superalloy;

(4) Improve organizational stability. Due to the long-life requirements of aero-engine components, it is also crucial to improve the long-term aging structure stability of GH4169 alloy.

2. Single crystal superalloy

Single crystal alloy materials have been developed to the fourth generation, and the temperature-bearing capacity has increased to 1140°C, which is close to the use temperature limit of metal materials. In the future, to further meet the needs of advanced aero-engines, the development of materials for blades needs to be further expanded, and ceramic matrix composites are expected to replace single crystal superalloys to meet the use of hot-end components in higher temperature environments.

The development difficulty and cycle of single crystal superalloy blades are related to their structural complexity. The development cycle of single crystal blades of ordinary complexity is relatively short, but it takes a long time to apply to aero engines. From single crystal solid blades to single crystal hollow blades to high-efficiency air-cooled complex hollow blades, the technical difficulty spans a large span, and the corresponding development cycle span is also large. Generally, it takes 1 to 2 years for a single crystal hollow blade of ordinary complexity from drawing confirmation, mold design to trial production, and then to small batch production. However, due to the complex service environment of single crystal blades, a large number of verification tests are required. Generally, it takes 5 to 10 years for a single crystal hollow blade with a common structure to be applied to aero engines after being developed, and some are developed with the engine. The progress may even take 15 years or more.