GH5188 is a solid solution strengthened cobalt-based high temperature Superalloy Material. with 14% tungsten added for solid solution strengthening, giving the alloy excellent high-temperature thermal strength. The addition of a higher chromium content and trace amounts of lanthanum provides the alloy with good high-temperature oxidation resistance, while also offering satisfactory formability and weldability. It is suitable for manufacturing parts in aircraft engines requiring high strength at temperatures below 980°C and oxidation resistance at temperatures below 1100°C. It can also be used in space engine and space shuttle applications. Various shaped products can be produced and supplied, such as thin plates, medium plates, strips, bars, forgings, wires, and precision castings.
GH5188 (GH188) material grade GH5188 (GH188).
GH5188 (GH188) equivalent grades: Haynes Alloy No. 188 (HA188), UNSR30188 (USA), KCN22W (France). Technical standards for GH5188 (GH188) material
Chemical composition of GH5188 (GH188)
| C | Cr | Ni | Co | W | Fe | B | La |
| 0.05~0.15 | 20.0~24.0 | 20.0~24.0 | Yu | 13.0~16.0 | ≤3.0 | ≤0.015 | 0.03~0.12 |
| Mn | Si | P≤ | S≤ | Ag≤ | Bi≤ | Pb≤ | Cu≤ |
| ≤1.25 | 0.20~0.50 | 0.020 | 0.015 | 0.0010 | 0.0001 | 0.0010 | 0.07 |
GH5188 (GH188) Heat Treatment Regime
Hot-rolled sheets: 1170–1190°C, air-cooled;
Cold-rolled strips and sheets: 1165–1230°C, rapid air-cooled;
Bars and forgings: 1180°C ± 10°C, rapid air cooling GH5188 (GH188) grades, specifications, and supply conditions: Supplied as cold-rolled sheets in thicknesses of 50.5–4 mm, hot-rolled medium plates in thicknesses of 64–14 mm, cold-rolled strips in thicknesses of 50.05–0.8 mm, and various sizes of bars, forgings, welding wire, and precision castings. Plates are supplied after solution treatment, acid washing, straightening, and edge trimming; strips are supplied in coils after solution treatment, acid washing, and edge trimming; plates are delivered after solution treatment with either grinding or turning; forgings are supplied in the solution-treated state; and precision castings are delivered in the as-cast state. GH5188 (GH188) Melting and Casting Processes The alloy is produced using vacuum induction melting followed by electroslag remelting or vacuum arc remelting processes. Precision castings are produced by vacuum induction melting followed by vacuum remelting of the master alloy ingot.
GH5188 (GH188) Application Overview and Special Requirements This Special Steel Material is widely used abroad in the manufacture of high-temperature components for gas turbines and missiles, such as combustion chambers, exhaust nozzles, and heat exchangers in the nuclear industry. In China, high-temperature components such as combustion chamber flame tubes and guide vanes made from this alloy have passed long-term testing and are now in production. In the manufacturing process of parts made from this alloy sheet, any process (such as heat treatment or welding) should prevent carburization and copper contamination to avoid impairing the alloy's mechanical properties and corrosion resistance.
GH5188 (GH188) Alloy Microstructure
In the solid solution state, GH5188 (GH188) consists of an austenitic matrix, M6C primary carbides, a small amount of LaxMy phase formed by the combination of M6C with lanthanum-rich compounds, and trace amounts of M3B2 and TiC phases. After prolonged exposure at high temperatures, M6C may decompose and precipitate as M23C6. In some batches, the L phase may precipitate, which can be re-dissolved into the matrix after solid solution treatment at 1180°C or prolonged exposure at 870–980°C followed by remelting.
The technical standards for plates, sheets, and strips of GH5188 (GH188) specify that the grain size in the supplied condition should not exceed Grade 4. The effect of solid solution temperature (holding time 10 minutes) on the grain size grade of plates.
| Solid solution temperature/°C | 1100 | 1120 | 1140 | 1150 | 1160 |
| Grain size/grade | 8~7(9) | 8~7 | 7~8 | 6~8 | 6~8(5) |
| Solid solution temperature/°C | 1170 | 1180 | 1190 | 1200 | 1220 |
| Grain size/grade | 5~7 | 5~7(4) | 5~6(4) | 4~6(3 ) | 3~5(2) |
GH5188 (GH188) part heat treatment process: The surface oxide film formed on this alloy after heating is firmly bonded to the base material. It is difficult to remove using the method of cleaning Stainless Steel oxide scale, and a composite alkali acid washing process should be used to remove the oxide scale.
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