Manufacturing technology of powder metallurgy superalloy

The manufacturing process of precipitation strengthened powder superalloy is characterized by adopting a fully inert process, that is, atomization and powder treatment under argon protection or vacuum to avoid oxidation of alloy powder. The process steps are as follows: ① Preparation of prealloyed gold powder. Argon atomization, vacuum atomization and rotating electrode atomization are mainly used. ② Powder treatment. Screening, mixing, removing oxide inclusions under argon protection, and then vacuum degassing. ③ Jack-up welding and sealing. The powder is put into a low-carbon steel, stainless steel or glass-ceramic cladding in vacuum, and then welded. ④ Hot pressing and hot working. Hot isostatic pressing or hot extrusion is mainly used, and hot die forging or superplastic isothermal forging can also be carried out. ⑤ Ultrasonic examination. ⑥ Heat treatment and machining.

In order to improve some properties of precipitation strengthened powder superalloy, some new technologies can be adopted, among which the most important ones are: ① rapid solidification and crushing. The cooling rate of the powder can reach 106℃/ s, thus further reducing segregation, making the composition and structure of the alloy more uniform, and expanding the solid solution range of the alloy, which can continue to improve the alloying degree and create an alloy with higher strength and service temperature, which can be used to manufacture multi-layer thin-plate air-cooled turbine blades. ② Special heat treatment process. Gradient annealing heat treatment can make the blade obtain directional recrystallization structure, while the center of the disk can obtain fine grain structure, thus manufacturing dual-performance disk to meet the requirements of turbine disk. ③ Thermoplastic processing technology. Pre-cooling the pre-alloyed powder to store strain energy in the powder, thus reducing the recrystallization temperature of the alloy, enabling hot isostatic pressing to be carried out at a lower pressure and temperature, obtaining a completely recrystallized fine-grained structure, making the material superplastic, and adopting a superplastic isothermal forging process; Thermoplastic technology can expand the application range of powder particle size, thus improving the utilization rate of powder.

Oxide dispersion strengthened superalloy is a kind of superalloy material with dispersion strengthening effect, in which ultrafine oxide particles with high thermal stability are uniformly distributed in metal or alloy matrix. Ods (Oxide Dispersion Strengthening) Superalloy for short.