Haynes 188 / HS-188 / UNS R30188
Material Introduction
Haynes 188, also known as HS-188, Alloy 188, or UNS R30188, is a cobalt-nickel-chromium-tungsten high-temperature alloy developed for severe oxidation, hot corrosion, and thermal cycling environments. It is widely used in combustor liners, transition ducts, flame holders, afterburner components, exhaust structures, turbine hot-section fabricated parts, and high-temperature sheet assemblies.
Unlike many cobalt-based casting alloys used mainly for turbine vane and nozzle segments, Haynes 188 is commonly supplied as wrought sheet, plate, bar, wire, and fabricated components. It should be evaluated as a high-performance cobalt-based alloy with excellent oxidation resistance, good fabricability, and reliable high-temperature strength. For complex parts requiring additive manufacturing, NewayAeroTech also provides Haynes 188 3D printing for customized high-temperature components.
International Naming Table
Region / Standard | Naming / Designation |
|---|---|
Commercial Name | Haynes 188 / HS-188 / Alloy 188 |
UNS | UNS R30188 |
Material Category | Cobalt-nickel-chromium-tungsten superalloy |
Common Product Forms | Sheet, plate, bar, wire, welded assemblies, 3D printed parts |
Typical Component Reference | Combustor liner, transition duct, flame holder, hot-section sheet structure |
Comparable Alloy Family | Haynes 25 / L-605, X-45, FSX-414, MAR-M 509, ECY-768, Hastelloy X |
Alternative Material Options
Haynes 188 is often selected for high-temperature fabricated components rather than cast nozzle or vane segments. When a project requires an alternative, the substitute should be chosen based on service temperature, oxidation resistance, hot corrosion behavior, formability, weldability, creep strength, coating compatibility, and component geometry.
Potential alternatives may include X-45, FSX-414, MAR-M 509 / M-509, ECY-768, or Hastelloy X, depending on whether the part is fabricated, welded, machined, 3D printed, or cast. For cast turbine components, special alloy casting may be more suitable. For wrought or fabricated hot-section structures, machining, forming, welding, and inspection control are usually more important than casting route selection.
Design Intent of Haynes 188
Haynes 188 was designed for high-temperature environments where oxidation resistance, thermal stability, fabricability, and weldability are critical. In gas turbine and aerospace systems, combustor liners, transition ducts, and flame holders must operate under hot combustion gas, thermal cycling, vibration, oxidation, and local stress concentration while maintaining dimensional stability and surface integrity.
The design intent of Haynes 188 is different from many cast cobalt superalloys. Instead of being used mainly for cast vane or nozzle geometries, Haynes 188 is especially valuable for thin-wall sheet structures, welded assemblies, formed parts, hot-section ducting, and high-temperature fabricated components. Its cobalt-nickel base chemistry provides thermal stability, chromium improves oxidation and hot corrosion resistance, and tungsten contributes solid-solution strengthening for elevated-temperature service.
Chemical Composition (wt%)
Element | Typical wt% |
|---|---|
Co | Balance |
Ni | ~20.0–24.0 |
Cr | ~20.0–24.0 |
W | ~13.0–16.0 |
Fe | ≤3.0 |
Mn | ≤1.25 |
Si | ≤0.35 |
C | ~0.05–0.15 |
La | Minor addition |
Note: Haynes 188 composition should be confirmed against the customer drawing, AMS/ASTM specification, purchase standard, or material certificate before manufacturing.
Physical Properties
Property | Typical Reference |
|---|---|
Material Type | Cobalt-nickel-chromium-tungsten superalloy |
Primary Product Form | Wrought sheet, plate, bar, wire, fabricated or additively manufactured parts |
Strengthening Mechanism | Solid-solution strengthening |
Service Environment | High-temperature oxidation and combustion gas exposure |
Oxidation Resistance | Excellent for high-temperature fabricated hot-section components |
Fabricability | Good formability and weldability compared with many cast cobalt alloys |
Mechanical Properties
Property | Engineering Relevance |
|---|---|
High-Temperature Strength | Supports combustor liner, transition duct, flame holder, and hot-section structure stability |
Oxidation Resistance | Excellent for repeated high-temperature exposure in combustion environments |
Thermal Fatigue Resistance | Important for start-stop cycles, thin-wall sections, welded assemblies, and duct structures |
Weldability | Useful for fabricated combustor and duct assemblies when welding procedures are controlled |
Formability | Suitable for sheet forming, ducting, liner structures, and high-temperature fabricated parts |
Creep Resistance | Supports long-term hot-section exposure when design stress and temperature are controlled |
Material Characteristics
Haynes 188 is characterized by excellent high-temperature oxidation resistance, good fabricability, strong thermal stability, and solid-solution strengthening from tungsten. Chromium improves oxidation and hot corrosion resistance, while nickel helps stabilize the alloy system and improves overall processing behavior. The alloy is especially useful where thin-wall components must survive combustion gas exposure while maintaining weld integrity and dimensional stability.
Compared with cast cobalt alloys such as MAR-M 509, X-45, or FSX-414, Haynes 188 is more commonly used for wrought and fabricated structures rather than investment-cast vane segments. This makes it highly suitable for combustor hardware, transition ducts, flame holders, high-temperature shields, exhaust structures, and welded duct assemblies. For service-exposed components, oxidation scale, thermal fatigue cracking, weld condition, distortion, coating degradation, and local thinning should be reviewed before repair or replacement manufacturing.
Manufacturing Process Performance
Haynes 188 performs well in high-temperature fabrication routes, including sheet forming, precision cutting, welding, machining, additive manufacturing, and assembly. For complex geometries, thin-wall hot-section structures, and prototype components, Haynes 188 3D printing may be considered when the part geometry is difficult to fabricate by conventional forming or machining.
For machined interfaces, mounting features, welded edges, slots, and tolerance-critical surfaces, superalloy CNC machining can be used to achieve final dimensional accuracy. If the component includes cooling features, local grooves, micro-slots, or difficult-to-machine details, superalloy EDM may be used for controlled feature generation. For thin-wall combustor or duct components, manufacturing control should focus on sheet thickness, distortion, weld quality, edge condition, heat-affected zone behavior, coating allowance, and final inspection.
Applicable Post-processing
Haynes 188 components may require solution annealing, stress relief, welding, machining, EDM, surface preparation, coating preparation, and inspection depending on the drawing, product form, and service condition. For welded combustor or duct assemblies, superalloy welding procedures should be reviewed based on joint design, filler material, heat input, distortion control, and post-weld inspection requirements.
For turbine hot-section components, surface cleaning, dimensional allowance, edge condition, and coating preparation should be controlled before final assembly or service. If thermal exposure protection is required, Thermal Barrier Coating (TBC) or another protective coating system may be evaluated according to the operating temperature and customer specification. Final validation through material testing and analysis is recommended for critical hot-section parts. Depending on component form and specification, chemical verification, weld inspection, dimensional inspection, hardness testing, metallographic review, and non-destructive testing may be required before delivery.
Common Applications
Haynes 188 is widely used in high-temperature aerospace and gas turbine fabricated components. Typical applications include combustor liners, transition ducts, flame holders, afterburner components, exhaust structures, turbine hot-section sheet parts, high-temperature shields, and welded duct assemblies. It is especially suitable for thin-wall components exposed to oxidation, combustion gas, thermal cycling, vibration, and local stress concentration.
In these applications, Haynes 188 components must resist oxidation, thermal fatigue, distortion, and weld-related failure during long-term service. The alloy is suitable where a wrought cobalt-based superalloy offers better forming and welding behavior than cast vane alloys. For replacement manufacturing, the original drawing, material specification, sheet thickness, weld requirement, heat treatment condition, coating requirement, inspection standard, and operating temperature should be reviewed before confirming Haynes 188 or an alternative alloy.
When to Choose Haynes 188
Choose Haynes 188 when the application requires a cobalt-based wrought or additively manufactured superalloy for high-temperature fabricated structures such as combustor liners, transition ducts, flame holders, exhaust structures, and hot-section sheet assemblies. It is most suitable when oxidation resistance, thermal fatigue resistance, weldability, formability, and high-temperature stability are more important than low material density or low material cost.
If Haynes 188 is not available or the project requires a substitute, alternatives should not be selected by name similarity alone. Hastelloy X, MAR-M 509, FSX-414, X-45, or ECY-768 may be considered only after comparing chemical composition, product form, forming route, welding behavior, mechanical performance, service temperature, coating compatibility, and turbine operating conditions. For new components, the safest approach is to request the drawing, material standard, sheet or bar condition, heat treatment requirement, weld specification, coating specification, and acceptance criteria before confirming manufacturability.
Engineering Selection Note
Haynes 188 should be evaluated as a high-temperature fabricated or additively manufactured superalloy rather than a direct replacement for every cobalt casting alloy. For RFQ evaluation, customers should provide the 2D drawing, 3D model, material specification, product form, sheet thickness or bar size, turbine model, service position, quantity, welding requirement, coating requirement, repair or new-build status, and inspection standard. This allows NewayAeroTech to determine whether Haynes 188 3D printing, CNC machining, EDM, forming, welding, heat treatment, coating preparation, material testing, or an alternative cobalt/nickel superalloy route is most appropriate for the component.
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