Haynes® 188 (Alloy 188) UNS R30188 Product Introduction
Haynes® 188, also known as Alloy 188 and designated as UNS R30188, is a cobalt-based superalloy renowned for its excellent high-temperature strength, oxidation resistance, and fabricability. This article provides a comprehensive introduction to Haynes® 188, covering its chemical composition, mechanical properties, performance at different temperatures, industry applications, shapes and sizes, production standards, welding and processing capabilities, advantages and disadvantages, and a comparison with similar alloys.
Chemical Composition
Haynes® 188 is primarily composed of cobalt with significant additions of chromium, tungsten, nickel, and other elements to enhance its mechanical and thermal properties:
| Element | Composition (%) |
|---|---|
| Cobalt (Co) | 39.0 – 41.0 |
| Chromium (Cr) | 20.0 – 24.0 |
| Nickel (Ni) | 20.0 – 24.0 |
| Tungsten (W) | 13.0 – 15.0 |
| Iron (Fe) | 3.0 max |
| Molybdenum (Mo) | 2.0 – 3.0 |
| Manganese (Mn) | 1.0 max |
| Silicon (Si) | 0.5 max |
| Carbon (C) | 0.05 – 0.15 |
| Boron (B) | 0.01 – 0.05 |
Mechanical Properties
Haynes® 188 exhibits exceptional mechanical properties suitable for high-temperature applications:
| Property | Value |
|---|---|
| Tensile Strength, ksi (MPa) | 130 – 150 (896 – 1034) |
| Yield Strength (0.2% offset), ksi (MPa) | 65 – 75 (448 – 517) |
| Elongation (% in 2 inches) | 20 – 30 |
| Hardness, Rockwell C (HRC) | 34 – 40 |
Performance Characteristics
Haynes® 188 offers several performance advantages:
- High-Temperature Strength: Maintains excellent mechanical properties at temperatures up to 1093°C (2000°F), making it suitable for gas turbine engine components, such as turbine blades, combustors, and afterburners.
- Oxidation Resistance: Exhibits superior resistance to oxidation and corrosion in high-temperature environments, extending component lifetimes.
- Fabricability: Provides good weldability and formability, allowing for complex shapes and configurations.
Industry Applications
Haynes® 188 is widely used in industries where high strength and corrosion resistance at elevated temperatures are critical:
| Industry Sector | Applications |
|---|---|
| Aerospace | Gas turbine components, including blades, combustors, and transition ducts. |
| Power Generation | Turbine hot-section components, heat exchangers, and industrial furnace parts. |
| Chemical Processing | High-temperature reactors, catalyst grid supports, and combustion chamber linings. |
Shapes and Sizes
Haynes® 188 is available in various forms and sizes to meet specific application needs:
- Forms: Sheets, plates, bars, forgings, and wire.
- Sizes: Thickness ranging from 0.5 mm to 100 mm for plates, and diameter ranging from 1 mm to 300 mm for round bars.
Production Standards
Haynes® 188 conforms to international production standards ensuring quality and reliability:
| Product Form | Shapes Available | Sizes Available | Production Standards |
|---|---|---|---|
| Plates/Sheets | Sheets, Plates | Thickness: 0.5 mm – 100 mm | ASTM B435, AMS 5608 |
| Bars/Rods | Round bars, Square bars | Diameter: 1 mm – 300 mm | ASTM B572, AMS 5608 |
| Forgings | Blocks, Discs, Rings | Size: Customized | ASTM B637, AMS 5772 |
Welding and Processing
Haynes® 188 offers good weldability and processing characteristics:
- Welding: Can be welded using methods such as TIG, MIG, and resistance welding. Preheating and post-weld heat treatment may be required to maintain properties.
- Machinability: Generally machined in the solution-annealed condition using carbide tools and appropriate cutting fluids.
Advantages and Disadvantages
| Aspect | Details |
|---|---|
| Advantages | Excellent high-temperature strength and oxidation resistance, good fabricability and weldability, and long service life in aggressive environments. |
| Disadvantages | Higher cost compared to standard materials, requires specialized processing and handling due to its high strength and alloying elements. |
Comparison with Similar Alloys
Haynes® 188 (UNS R30188) is often compared with other cobalt-based superalloys such as Haynes® 25 and Haynes® 230. Here’s a brief comparison:
| Alloy Type/Property | Haynes® 188 | Haynes® 25 | Haynes® 230 |
|---|---|---|---|
| Chemical Composition | Cobalt, chromium, nickel, tungsten, molybdenum for high-temperature strength and oxidation resistance. | Cobalt, chromium, nickel, tungsten, molybdenum for high-temperature strength and oxidation resistance. | Cobalt, chromium, nickel, tungsten, molybdenum for high-temperature strength and oxidation resistance. |
| Mechanical Properties | High tensile and yield strength, good ductility and formability. | Similar tensile and yield strength, good resistance to thermal fatigue and oxidation. | Higher tensile and yield strength compared to Haynes® 188, excellent thermal stability and corrosion resistance. |
| Applications | Gas turbine components, aerospace hot-section parts, industrial furnace components. | Aerospace components, gas turbine combustors, industrial furnace parts. | Aerospace and industrial gas turbine components requiring high-temperature strength and corrosion resistance. |
This detailed article introduces Haynes® 188 (Alloy 188, UNS R30188), highlighting its chemical composition, mechanical properties, performance characteristics, industry applications, available forms and sizes, production standards, welding and processing capabilities, as well as advantages, disadvantages, and a comparison with similar alloys. Engineers and professionals seeking a reliable, high-temperature superalloy for demanding applications in aerospace, power generation, and chemical processing will find Haynes® 188 well-suited for use in extreme environments.