GH4720Li high temperature alloy

GH4720Li (U.S. grade Udimet720Li) alloy is a high-strength, corrosion-resistant, age-strengthened new nickel-based high-temperature alloy developed by the U.S. Specialmetals Corporation, mainly used to make compressor discs and turbine discs used at 650 to 750°C and turbine discs used at 900°C for a short period of time.

GH720Li has excellent high-temperature performance, compared with other nickel-based high-temperature alloys, the outstanding feature of this alloy is the total amount of Al + Ti up to 7. 5% while containing very low carbon, so that the volume fraction of the main strengthening phase γ' (Ni3( Al, Ti)) in the matrix can reach 40% to 50%, the precipitation temperature is as high as 1160 ℃ or so. Due to the high precipitation temperature of its own γ' phase, and as a turbine disk material needs to have a uniform fine crystal organization to provide high tensile strength and fatigue life, GH720Li alloy needs to be deformed in the two-phase region containing a large amount of eutectic γ' phase in actual production, and its recrystallization mechanism has certain special characteristics. GH4720Li is a Ni-Cr-Co based precipitation hardening deformed high temperature alloy, the use temperature is at 750℃, the alloy has high high temperature strength, fatigue and creep resistance; good corrosion and oxidation resistance, and long-term organizational stability, suitable for making aero-engine turbine wheel discs and turbine blades, the main products are hot rolled and forged bars, disc forgings, etc. GH4720Li high-temperature alloy has been used to make aero-engine turbine discs and passed the test run examination. It is also used to make new generation strategic missile and large thrust engine integral turbine rotor, as well as ground gas turbine turbine discs and other parts that work under 750℃ for a long time. GH4720Li high-temperature alloy ingots have more serious component segregation, which makes the ingots less thermoplastic and prone to cracking during deformation, and the organization is very sensitive to thermal processing parameters, so isothermal forging should be selected. After long-term aging at 750℃×2000h, no harmful phase precipitation was found.