AMS 5608 Haynes 188 Sheet
AMS 5608 Haynes 188 Sheet
If you are familiar with Inconel 625 or Hastelloy X, you know they offer high-temperature resistance, yet their strength begins to decline above 800°C. Haynes 188 is different; it is a cobalt-based alloy, meaning its matrix is cobalt rather than nickel.
Cobalt has a higher melting point than nickel and a more stable crystal structure. The alloy retains impressive strength even after prolonged exposure to temperatures up to 1095°C. To put that temperature in perspective: it is comparable to the flame temperature inside an aircraft engine combustion chamber.
Customers purchasing AMS 5608 sheet metal are typically dealing with applications such as aircraft engine combustion chambers, afterburners, and transition ducts-components that must withstand the blast of flames exceeding 1,000°C while maintaining sufficient structural integrity to avoid deformation.
Commonly Supplied Sizes
Thickness: AMS 5608 applies to plates with a thickness of ≤2 inches (approx. 50.8 mm).
Common Thicknesses: 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.5 mm, 2.0 mm, 3.0 mm, etc.
Dimensions: Can be cut to specific sizes upon request.
Delivery Condition (Crucial!):
Solution-Annealed Condition: The standard delivery condition for Haynes 188 plate. Solution treatment temperature is 1163–1191°C (2125–2175°F), followed by rapid cooling or water quenching.
Note: Do Not Anneal At Temperatures Below The Solution Treatment Temperature; doing so will cause carbide precipitation, which impairs material performance.
We are available at any time to provide quotes and dimensional information-please feel free to contact us.
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Chemical Composition
AMS 5608, key chemical composition points (wt.%)
|
Element
|
Min | Max |
| Carbon | 0.05 | 0.15 |
| Manganese | -- | 1.25 |
|
Silicon
|
0.20 | 0.05 |
|
Phosphorus
|
-- | 0.02 |
|
Sulfur
|
-- | 0.015 |
|
Chromium
|
20.00 | 24.00 |
|
Nickel
|
20.00 | 24.00 |
|
Tungsten
|
13.00 | 16.00 |
|
Lanthanum
|
0.02 | 0.12 |
|
Boron
|
-- | 0.015 |
|
Iron
|
-- | 3.00 |
|
Cobalt
|
Remainder |
A key point to note: Lanthanum (La) serves as the "ID card" for Haynes 188. While many cobalt-based alloys look alike, only Haynes 188 contains added lanthanum. When receiving material, check the lanthanum content; it must fall within the 0.03–0.12% range to qualify. If the content is lower, oxidation resistance will be compromised.
Minimum tensile properties
For products with a nominal thickness of 0.010 inch (0.25 mm) or less, performance may be determined using test specimens with a nominal thickness not exceeding 0.025 inch (0.64 mm) taken from the same master roll and heat.
|
Nominal Thickness
Millimeters
|
Tensile Strength
MPa
|
Yield Strength at 0.2% Offset
MPa
|
Elongation in 50 mm or 4D
%
|
|
Up to 0.25, incl
|
862 | 379 |
Report
|
|
Over 0.25 to 0.51, incl
|
862 | 379 | 40 |
|
Over 0.51
|
862 | 379 | 45 |
|
Nominal Thickness
Millimeters
|
Tensile Strength
MPa
|
Yield Strength at 0.2% Offset
MPa
|
Elongation in 50 mm or 4D
%
|
|
Up to 0.25, incl
|
621 | 248 |
Report
|
|
Over 0.25 to 0.51, incl
|
621 | 248 | 40 |
|
Over 0.51
|
621 | 248 | 50 |
Bending parameters
|
Nominal Thickness
Inches
|
Nominal Thickness
Millimeters
|
Bend
Factor
|
|
Up to 0.050, incl
|
Up to 1.27, incl
|
1.5 |
|
Over 0.050 to 0.1874, incl
|
Over 1.27 to 4.760, incl
|
2.0 |
Stress-Rupture Properties at 1700 °F (927 °C)
|
Nominal Thickness
Millimeters
|
Stress
MPa
|
Elongation in 50 mm or 4D
%, Min
|
|
Up to 0.51, incl
|
62.1 | 8 |
|
Over 0.51
|
75.8 | 15 |
Procurement Specifications and Industry Standards
Upon receiving the customer's requirement for AMS 5608, Lork Group established this as the standard for the aerospace-grade sheet material. We mandate that the following items be strictly specified on the purchase order:
Executive Standards (Core):
AMS 5608: Aerospace Material Specification issued by SAE International; the sole authoritative standard for Haynes 188 sheet, strip, and plate. It covers chemical composition, mechanical properties (at room and elevated temperatures), grain size, bendability, surface quality, and non-destructive testing requirements.
AMS 5772: Standard for bars, forgings, and rings.
AMS 5801: Standard for welding wire.
UNS R30188: Material identification number.
W.Nr. 2.4683: Corresponding German standard grade.
Domestic equivalent grade: GH5188 (GB/T 14992).
Melting Process (Affects Purity):
AMS 5608 mandates the use of secondary refining processes, such as Vacuum Induction Melting (VIM) followed by Vacuum Arc Remelting (VAR) or Electroslag Remelting (ESR). This ensures that gas content, inclusions, and harmful elements are minimized.
Key Points of the Quality Inspection Process
1. Chemical Composition Report:
Spectroscopic analysis (PMI). Key elements to monitor:
Lanthanum (La): 0.03–0.12% (characteristic marker for Haynes 188)
Tungsten (W): 13.0–15.0% (insufficient levels result in inadequate strength)
Chromium (Cr): 21.0–23.0% (insufficient levels compromise oxidation resistance)
Cobalt (Co): Balance (approx. 39–42%) (matrix element)
2. Mechanical Properties:
Room-temperature tensile test report. Tensile strength ≥830 MPa; elongation ≥35%
3. Hardness Testing:
Typical values in the solution-annealed state: HRC 20–25 or HBS 200–240
4. Non-Destructive Testing (NDT):
Ultrasonic testing: May be required for critical plate components to detect internal cracks, inclusions, or delamination
Surface inspection: Dye penetrant testing may be required to detect surface micro-cracks
5. Bending Performance:
AMS 5608 requires that plates in the solution-annealed state pass a bend test (e.g., 180° bend with a mandrel diameter equal to the plate thickness)
6. Dimensions and Surface Quality:
Plate surfaces must be free from cracks, folds, and scratches. Thickness is verified via multi-point spot checks using a micrometer.
Lork Group
Marketing Operations Department
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