GH4099 (GH99) is a highly alloyed nickel-based aging plate alloy that is strengthened by a combination of cobalt, tungsten, aluminum, titanium and other elements to give the alloy excellent thermal strength. This alloy can be used for a long time in a temperature environment below 900 °C, and its maximum operating temperature can even reach 1000 °C. The microstructure of the alloy is stable, and the performance of both cold and hot working forming and welding process is satisfactory. It is especially suitable for the manufacture of aero engine combustion chambers, afterburner combustion chambers and other plate load-bearing welded structural parts that need to withstand high temperature and heavy load. GH4099 chemical composition
The large plate parts of GH4099 alloy can be used directly without quenching and tempering after solution treatment, showing its excellent mechanical properties. Its main product forms include plates and wires, and can also produce plates and forgings. For the plate of GH4099 alloy, the heat treatment system requires air cooling in the temperature range of 1120-1160;For electrodes, air cooling is required in the temperature range of 1100-1140. GH4099 Physical Properties
Overseas similar alloy plates are usually water-cooled or air-cooled in the temperature range of 1080-1100, and then aged for 5 hours at 900 degrees or 8 hours at 800. The ** status of GH4099 varies according to the type and specification, for example, δ08-4.0mm cold-rolled sheet and d03-10mm cold drawing needs to be solution treated and alkali pickled**. gh4099The minimum value of the mechanical properties of the alloy at room temperature
In terms of smelting and casting process, GH4099 alloy is produced by vacuum induction melting plus electroslag remelting. This process ensures the purity and uniformity of the alloy, further enhancing its properties. The application of GH4099 alloy has been widely recognized, and aircraft engine afterburner adjustable nozzle housings made of its plates have passed long-term use evaluation and are put into mass production. This application reduces the weight of the engine and extends its service life. 
For the heat treatment method of GH4099 parts, it is recommended that the temperature of the final solution treatment is 1140, and the appropriate aging specification is 900 10, 4 hours, air cooling. If the parts need to be manufactured after welding, they can be manufactured by multiple stretches under 1100, after such heat treatment, the stress-relieving parts have high thermal strength and good comprehensive properties. In the process of solution treatment of parts or assemblies, the recommended holding time is 10-15min for plates with a thickness of less than 2mm, and the insulation time can be appropriately extended for plates with a thickness greater than 2mm. The final solution treatment must be air-cooled, and the intermediate heat treatment can be air-cooled or water-cooled according to the specific situation. 
For large plate parts made of GH4099 alloy, if limited by equipment conditions, they can be used directly without quenching and tempering after solution treatment or welding combination of 1140 10. In addition, solution treatment is recommended in the temperature range of 1080-1100 followed by aging treatment. The specification of aging treatment is h or h, air cooling. The highest plasticity can be obtained by processing at 900 degrees, while the highest strength can be obtained by processing at 800 degrees. The appropriate aging treatment specification can be selected according to the working conditions of the part. 
In terms of improving the high-temperature durability of GH4099 alloy, the strength and durability of the alloy can be effectively improved by adjusting the content of alloying elements such as W and Mo and controlling the appropriate range of MG elements. In addition, the temperature and time of solution treatment have an important impact on the microstructure of the alloy. The temperature and time of solution treatment determine the size and growth rate of the double crystals. Therefore, the reasonable selection of the temperature and time of solution treatment is crucial to optimize the microstructure and properties of the alloy.