GH80A
Material Grade: GH80A Superalloy
British Grade: Nimonic80A
1. Overview of GH80A superalloy:
GH80A is a nickel-chromium matrix, adding aluminum, titanium to form a γ′ phase diffusion strengthened superalloy, except for the aluminum content is slightly higher, the other is similar to GH4033, the use temperature is 700~800 °C, at 650~850 °C has good creep resistance and oxidation resistance. The alloy has good cold and hot working performance, and is mainly supplied with hot-rolled bars, cold-drawn bars, hot-rolled plates, cold-rolled plates, strips and ring parts, etc., which are used to manufacture engine rotor blades, guide vane bearings, bolts, blade lock plates and other parts.
1. GH80A material grade: GH80A.
2. GH80A similar grade: Nimonic80A (UK).
3. Technical standards for GH80A materials:
4. Chemical composition of GH80A: see Table 1-1.
Table 1-1%.

Note: B is added according to the calculated amount, and trace amounts of Ce, Zr, and Mg elements are allowed.
5. GH80A heat treatment system: bars for blades are: 1080 °C± 10 °C, 8h, air cooling +700 °C± 5 °C, 16h, air cooling. Hot-rolled, forged and cold-drawn bars: according to the provisions of Table 1-2. Rolled rings: (1050~1080°C) ±10°C, not more than 2h, water-cooled +750°C±5°C (or +700°C±5°C), 4h (or 16h), air-cooled. Hot-rolled sheets, cold-rolled sheets and strips are: supply state +750°C±10°C, 4h, air cooled.
Table 1-2

Table 1-3

Table 1-4

6. GH80A variety specifications and supply status: supply hot-rolled bars with a diameter of d20~55mm, hot-rolled or forged bars with a diameter of no more than 300mm. Cold-drawn bars are supplied with round bars with a diameter of 8~45mm and hexagonal bars with an inscribed round diameter of D8~36mm. Rolled parts with an outer diameter of 1,000 mm, an inner diameter of 900 mm, and a height of 130 mm are supplied. We supply hot-rolled sheet with a thickness of no more than 9.5 mm, cold-rolled sheet with a thickness of no more than 4.0 mm, and cold-rolled strip with a thickness of no more than 0.8 mm. Hot-rolled bars for blades are supplied without heat treatment, and their surfaces should be completely polished or polished. Hot-rolled bars for machining are supplied with solution treatment and descaling. Cold-drawn bars for upsetting are supplied in a cold-drawn and polished state, cold-drawn bars for machining are supplied in a cold-drawn solution treated and descaled state, and hot-working bars are supplied in a manufactured state and descaled (for forgings and bars, the surface roughness should not be less than 3.2μm). Rolled rings are supplied in solution and roughing condition. Hot-rolled plates, cold-rolled sheets and strips are supplied after softening, alkali pickling, trimming and leveling or straightening.
7. GH80A smelting and casting process: the bars and plates for blades are made by vacuum induction smelting and electroslag remelting process. Rolled rings and hot-rolled, forged and cold-drawn bars are processed by induction melting plus electroslag remelting, or vacuum induction melting plus vacuum arc remelting, or vacuum induction melting plus electroslag remelting.
8. GH80A application overview and special requirements: the alloy is mainly used as engine rotor blades, guide vane bearings, fan-shaped mounting rings, bolts, blade lock plates and other parts.
2. Physical and chemical properties of GH80A:
1. Thermal properties of GH80A:
(1) GH80A melting temperature range: melting point 1405 °C^[1]。
(2) GH80A thermal conductivity: see Table 2-1.
Table 2-1^[1]

(3) GH80A line expansion coefficient: see Table 2-2.
2. GH80A density: ρ=8.15g/cm^3[2]。
Table 2-2^[2]

3. Electrical properties of GH80A: room temperature ρ=1.23×10^-6Ω.m^[1]。 
4. GH80A magnetic properties: non-magnetic.
5. Chemical properties of GH80A: Antioxidant properties of GH80A: The oxidation rate of 100h in air medium is shown in Table 2-3.
Table 2-3^[3]

3. Mechanical properties of GH80A: The specified properties of GH80A bars for turbine blades are shown in Table 3-1.
Table 3-1

Technical standards	Number of logarithms in series of specimens	Long-lasting performance
		θ/℃	σ/MPa	Breaking time/h
				A single value	average value	Range value (Rmax) = (F) · ()
WS9-7009-1996	3	750	340	≥23	≥32	≤0.6× actual average

4. GH80A organizational structure:
1. GH80A phase change temperature:
2. GH80A time-temperature-tissue transition curve:
3. GH80A alloy microstructure: Structural characteristics of blade blank treated according to different heat treatment specifications: 1080 °C± 10 °C, 8h, air cooling: γ′ phase in the matrix and some M7C3 and M23 C at 1080 °C Type 6 grain boundary carbides are dissolved into solid solutions. During cooling, chromium-rich carbides of type M7C3 andM23C6 are formed at grain boundaries. M7C3 precipitates out approximately above 1000 °C and transforms toM23C6 at lower temperatures. M23C6 is precipitated at 750~1000 °C, and can also nucleate independently to form grain boundary carbides. Therefore, at 1080 °C± 10 °C, 8 h, after air cooling, the grain boundaries show discontinuous M7C3 andM23C6, and there are γ′ phases and MC in the crystal.
1080°C±10°C, 8h, air-cooled +700°C±5°C, 16h, air-cooled: The alloy is aged at 700°C±5°C and 16h on the basis of solid solution structure, andM7C3 on the grain boundary continues to be converted to M23C6, so the precipitation ofM23C6 called continuous M23C6 on the grain boundary, the γ′ phase in the grain also grows into a spherical particle^[4]。
5. GH80A process performance and requirements:
1. GH80A forming performance:
(1) GH80A forging: the alloy has good forging properties. The heating temperature of the ingot is 1120~1150 °C, and the forging temperature is not less than 1000 °C. The forging stop temperature is not lower than 950°C^[2]。
(2) GH80A hot-rolled plate: the rolling heating temperature is 1120~1150 °C, and the rolling temperature is not less than 930 °C^[2]。
(3) Forging of GH80A turbine blades: The blank for turbine blades should be sprayed with protective lubricant according to the specified process requirements, and can be heated in the furnace only after drying. The parts blank is heated in the electric furnace, the loading temperature is 800 °C± 20 °C, the heat preservation is 60min, the heating temperature is 1090 °C±10 °C, the heat preservation is 35min, the forging temperature is 1090 °C, the forging temperature is 950 °C, the top forging is carried out on the horizontal forging machine, and the die chamber is lubricated with molybdenum disulfide before forging. The intermediate process of forging parts blanks should be solution treated, with a heating temperature of 1130 °C± 10 °C, heat preservation for 60min, and air cooling. After sand blowing, the protective lubricant is sprayed according to the specified process requirements, and then heated in the furnace after drying. The parts blank is then installed, heated and kept warm according to the above provisions, and the final forging is carried out on the crank press, and the mold chamber is lubricated with molybdenum disulfide before forging.
2. GH80A welding performance: the alloy can be automatically butted argon arc welding and seam welding.
(1) GH80A automatic tungsten argon arc welding (butting) specification without welding wire: see Table 5-1.
Table 5-1^[2]

Note: Before welding, grind the sample with an abrasive cloth and clean it with acetone, and the thickness is not more than 1.2mm plate without filling welding wire, and it is welded and formed at one time.
(2) GH80A weld specification: see Table 5-2.
Table 5-2^[2]

(3) Mechanical properties of GH80A welded joints: see Table 5-3.
Table 5-3^[2]

Note: The data in this table are the tensile test data processing results of two batches of plates and 2 samples per batch.
3. GH80A parts heat treatment process: the heat treatment process of parts is carried out according to the heat treatment system of the corresponding material technical standards. For the stamping and forming parts of plates and strips, intermediate vacuum annealing is required after each forming time, 1060 °C± 10 °C, 10min, argon fan cooling, the final heat treatment of the parts is aging treatment in a vacuum furnace, 750 °C± 10 °C, 4h, argon fan cooling. For the local work hardening of the blade in the manufacturing process after solution (before aging), argon or hydrogen protective surface annealing should be carried out according to the specified requirements, and the annealing temperature is 1070~1090 °C.
4. GH80A surface treatment process:
5. GH80A cutting and grinding performance: GH80A has good machinability, and it has good machinability in the complete heat treatment state.
6. GH80A variety specifications and supply status:
1. Variety classification: GH80A seamless pipe, GH80A steel plate, GH80A round bar, GH80A forging, GH80A flange, GH80A ring, GH80A welded pipe, GH80A steel belt, GH80A wire and supporting welding consumables.
2. Delivery status: seamless tube: solid solution + acid white, length can be fixed; Plates: solid solution, pickling, trimming; Welded pipe: solid solution acid white + RT% flaw detection, forgings: annealing + polishing; The bar is in a forged state, the surface is polished or polished; The strip is delivered by cold rolling, solution soft state, and descaling; The filaments are delivered in solution pickled discs or straight strips, solution straight strips in finely polished condition.