Nickel alloy GH80A Plate Nimonic80A superalloyRoll Steel

GH80A
   Material grade: GH80A superalloy
   British grade: Nimonic80A
 Overview of GH80A superalloy:
   GH80A is a high-temperature alloy with nickel-chromium as the matrix, and aluminum and titanium are added to form a dispersion-strengthened γ' phase. Except for the slightly higher aluminum content, the others are similar to GH4033. Creep resistance and oxidation resistance. The alloy has good cold and hot working properties. It mainly supplies hot-rolled bars, cold-drawn bars, hot-rolled sheets, cold-rolled sheets, strips, and annular parts, etc., for the manufacture of engine rotor blades, guide vane supports, bolts, Blade lock plate and other parts.
   1. GH80A material grade: GH80A.
   2, GH80A similar grades: Nimonic80A (UK).
   3. Technical standard of GH80A material:
   4. Chemical composition of GH80A: see Table 1-1.

Note: B is added according to the calculated amount, and trace amounts of Ce, Zr and Mg are allowed to be added.
   5. GH80A heat treatment system: bar for blades: 1080℃±10℃, 8h, air cooling+700℃±5℃, 16h, air cooling. Hot-rolled, forged and cold-drawn bars: according to the provisions of Table 1-2. Rolled rings: (1050～1080℃)±10℃, no more than 2h, water cooling +750℃±5℃ (or +700℃±5℃), 4h (or 16h), air cooling. Hot-rolled sheet, cold-rolled sheet and strip are: supply state +750℃±10℃, 4h, air cooling.
   Table 1-2

Table 1-3

 Table 1-4

6. GH80A varieties, specifications and supply status: supply hot-rolled bars for blades with a diameter of d20-55mm, and hot-rolled or forged bars with a diameter of not more than 300mm. Cold-drawn rods supply round rods with a diameter of 8-45mm and hexagonal rods with an inscribed circle diameter of d8-36mm. We supply rolled pieces with an outer diameter of 1000mm, an inner diameter of 900mm and a height of 130mm. We supply hot-rolled sheet with thickness not greater than 9.5mm, cold-rolled sheet with thickness not greater than 4.0mm, and cold-rolled strip with thickness not greater than 0.8mm. Hot-rolled bars for blades are supplied without heat treatment, and their surfaces should be completely ground or polished. Hot-rolled bars for machining are solution-treated and supplied in a descaled state. 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 the bar used in the forging plant, it should be supplied after polishing, and its surface roughness should not be less than 3.2μm). Rolled rings are supplied in solution treated and roughed condition. Hot-rolled sheet, cold-rolled sheet and strip are supplied after softening, alkaline pickling, trimming and leveling or straightening.

7. GH80A smelting and casting process: vacuum induction melting and electroslag remelting process are adopted for the bar and plate for blades. Rolled rings and hot-rolled, forged and cold-drawn bars use induction melting and electroslag remelting, or vacuum induction melting and vacuum arc remelting, or vacuum induction melting and electroslag remelting.
   8. Application overview and special requirements of GH80A: This alloy is mainly used for engine rotor blades, guide vane supports, sector mounting rings, bolts, blade lock plates and other parts.

Physical and chemical properties of GH80A:
   1. GH80A thermal performance:
   (1), GH80A melting temperature range: melting point 1405 ℃ [1].
   (2) Thermal conductivity of GH80A: see Table 2-1.
   Table 2-1[1]

 (3), GH80A linear expansion coefficient: see Table 2-2.
   2. GH80A density: ρ=8.15g/cm3[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 GH80A in the air medium test for 100h is shown in Table 2-3.
   Table 2-3[3]

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

GH80A organizational structure:
   1. GH80A phase transition temperature:
   2. GH80A time-temperature-structure transformation curve:
   3. Microstructure of GH80A alloy: Microstructure characteristics of blade blank treated according to different heat treatment specifications: 1080℃±10℃, 8h, air cooling treatment: γ′ phase and some M7C3 and M23C6 grain boundary carbides in the matrix dissolve at 1080℃ into a solid solution. Chromium-rich carbides of M7C3 and M23C6 types are formed at grain boundaries during cooling. M7C3 precipitates out above about 1000°C and transforms to M23C6 at lower temperatures. M23C6 precipitates at 750-1000 °C, and can also nucleate independently to form grain boundary carbides. Therefore, after air cooling at 1080℃±10℃ for 8h, discontinuous M7C3 and M23C6 appeared on the grain boundary, and there were γ' phase and MC in the grain.
   1080℃±10℃, 8h, air cooling+700℃±5℃, 16h, air cooling treatment: the alloy is aged at 700℃±5℃ for 16h on the basis of the solid solution structure, and the M7C3 on the grain boundary continues to transform into M23C6. The continuous M23C6 is precipitated on the grain boundary, and the γ' phase in the grain also grows into spherical particles [4]. 

5. GH80A process performance and requirements:
   1. GH80A forming properties:
   (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 lower than 1000°C. Stop forging temperature is not lower than 950 ℃ [2].
   (2), GH80A hot-rolled sheet: the rolling heating temperature is 1120-1150 °C, and the rolling stop temperature is not lower than 930 °C [2].
   (3) Forging of GH80A turbine blades: The blanks for turbine blades should be sprayed with protective lubricant according to the specified process requirements, and can be heated in the furnace after drying. The part blank is heated in an electric furnace, the furnace temperature is 800℃±20℃, the heat preservation is 60min, the heating temperature is 1090℃±10℃, the heat preservation is 35min, the forging temperature is 1090℃, and the stop forging temperature is 950℃. Before lubricating the die cavity with molybdenum disulfide. The intermediate process of blank forging of parts should be solid solution treatment, the heating temperature is 1130℃±10℃, the heat preservation is 60min, and the air cooling is performed. After sand blasting, the protective lubricant is sprayed according to the specified process requirements, and then heated in the furnace after drying. The blanks of the parts are then charged, heated, and kept warm according to the above regulations, and final forging is performed on a crank press. Before forging, molybdenum disulfide is used to lubricate the die cavity.

2. GH80A welding performance: the alloy can perform automatic butt argon arc welding and seam welding.
   (1) Specification for automatic tungsten argon arc welding (butt) of GH80A without welding wire: see Table 5-1.
   Table 5-1[2]

Note: Grind the sample with emery cloth and clean it with acetone before welding. The thickness of the plate is not more than 1.2mm without adding welding wire, and it is formed by one welding.
   (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 refer to the processing results of the tensile test data of two batches of plates and two samples in each batch.
   3. Heat treatment process of GH80A parts: The heat treatment process of parts is carried out according to the heat treatment system of the corresponding material technical standards. For stamping and forming parts of sheet and strip, intermediate vacuum annealing is required after each forming, 1060℃±10℃, 10min, argon fan cooling, and the final heat treatment of the parts is aging treatment in a vacuum furnace, 750℃± 10 ℃, 4h, argon fan cooling. For the local work hardening of the blade in the manufacturing process after solution solution (before aging), argon or hydrogen protection surface annealing should be carried out according to the specified requirements, and the annealing temperature is 1070-1090℃.
   4. GH80A surface treatment process:
   5. GH80A cutting and grinding performance: GH80A has good machinability, and fully heat-treated state has good machinability.