Alloy 188,Udimet 188,UNS R30188,E FORU

### **Alloy 188 / Udimet® 188 / UNS R30188** **Cobalt-Chromium-Nickel-Tungsten Superalloy for Extreme Temperature Applications** 

 --- #### **1. Overview

** **Alloy 188**, commercially known as **Udimet® 188**, is a cobalt-chromium-nickel-tungsten superalloy that delivers an outstanding combination of high-temperature strength, exceptional oxidation resistance, and excellent fabricability. This solid-solution strengthened alloy maintains remarkable mechanical properties at temperatures up to 1100°C (2012°F) and exhibits superior resistance to thermal fatigue and creep deformation. The strategic addition of lanthanum significantly enhances the alloy's oxidation resistance by forming a stable, adherent protective scale, making it ideal for long-term service in extreme environments.

 --- #### **2. Chemical Composition (Weight %)

** The typical chemical composition of Udimet 188 is outlined below. The balance is Cobalt (Co). 

| Element | Content (%) | Key Function | 

| :--- | :--- | :--- | 

| **Cobalt (Co)** | Balance | Forms the primary matrix with exceptional high-temperature structural stability and strength retention. | 

| **Chromium (Cr)** | 21.0 - 23.0 | Provides superior oxidation and hot corrosion resistance through formation of a protective Cr₂O₃ scale. | 

| **Tungsten (W)** | 13.0 - 15.0 | Primary solid-solution strengthener; significantly enhances high-temperature strength and creep resistance. |

| **Nickel (Ni)** | 20.0 - 22.0 | Stabilizes the austenitic structure and improves metallurgical stability at elevated temperatures. | 

| **Iron (Fe)** | 2.0 max | Controlled impurity to maintain corrosion resistance. | 

| **Lanthanum (La)** | 0.04 - 0.10 | Dramatically improves oxidation resistance by enhancing scale adhesion and reducing spallation. | 

| **Manganese (Mn)** | 1.00 max | Improves hot workability and acts as a deoxidizer. | 

| **Silicon (Si)** | 0.20 - 0.40 | Enhances oxidation resistance through silica formation in the protective scale. | 

| **Carbon (C)** | 0.08 - 0.14 | Forms carbides for secondary strengthening and improved wear resistance. | 

| **Boron (B)** | 0.008 - 0.020 | Enhances creep strength and grain boundary cohesion. | 

| **Phosphorus (P)** | 0.015 max | Controlled impurity. | 

| **Sulfur (S)** | 0.010 max | Controlled impurity to prevent hot shortness. | 

 --- #### **3. Physical Properties** 

 | Property | Value / Condition | 

| :--- | :--- | 

| **Density** | 9.15 g/cm³ (0.331 lb/in³) | 

| **Melting Range** | ~ 1340 - 1420 °C (2445 - 2590 °F) | 

| **Mean Coefficient of Thermal Expansion** | 20 - 540°C (68 - 1000°F): **14.3 x 10⁻⁶/°C** (7.9 x 10⁻⁶/°F)

20 - 980°C (68 - 1800°F): **15.9 x 10⁻⁶/°C** (8.8 x 10⁻⁶/°F) | 

| **Thermal Conductivity** | 10.2 W/m·K (71 Btu·in/hr·ft²·°F) at 21°C (70°F)
23.8 W/m·K (165 Btu·in/hr·ft²·°F) at 540°C (1000°F) | 

| **Specific Heat** | 423 J/kg·K (0.101 Btu/lb·°F) at 21°C (70°F) | 

| **Electrical Resistivity** | 0.96 μΩ·m at 21°C (70°F) | 

| **Modulus of Elasticity (Young's Modulus)** | 250 GPa (36.3 x 10⁶ psi) at 21°C (70°F) | 

| **Magnetic Permeability** | Essentially non-magnetic in all conditions. | 

 --- #### **4. Mechanical Properties

 (Typical for Annealed Condition)** 

 | Property | At Room Temperature | At 815°C (1500°F) | At 980°C (1800°F) | 

| :--- | :--- | :--- | :--- | 

| **Tensile Strength** | 980 - 1250 MPa (142 - 181 ksi) | 320 - 380 MPa (46 - 55 ksi) | 170 - 220 MPa (25 - 32 ksi) | 

| **Yield Strength (0.2% Offset)** | 490 - 650 MPa (71 - 94 ksi) | 230 - 280 MPa (33 - 41 ksi) | 130 - 170 MPa (19 - 25 ksi) | 

| **Elongation (in 50 mm / 2 in)** | 45% - 60% | 50% - 70% | 70% - 90% | | **Hardness (Rockwell B)** | 94 - 102 HRB | - | - | -

-- #### **5. International Standards

** Udimet 188 conforms to the following international specifications: 

 *   **ASTM:**    

*   **B435:** UNS R30188 Plate, Sheet, and Strip    

*   **B572:** UNS R30188 Rod/Bar    

*   **B639:** UNS R30188 Billet and Bar for Aerospace Applications 

*   **AMS:**    

*   **AMS 5772:** Sheet, Strip, and Plate    

*   **AMS 5803:** Welding Wire    

*   **AMS 5792:** Bar and Forging Stock 

*   **UNS:** R30188 *  

 **ISO:**    

*   **ISO 5832-7:** Wrought cobalt-chromium-nickel-molybdenum-iron alloy 

*   **EN (European Standard):** 2.4984 

*   **AECMA:** PR EN 3962 

 --- #### **6. Product Applications

** Udimet 188 serves critical functions in the most demanding high-temperature applications: 

 *   **Aerospace & Defense:**    

*   Turbine blades and vanes in gas turbine engines    

*   Combustion chambers and afterburner components    

*   Exhaust nozzles and thrust reversers    

*   Rocket engine components and nozzle inserts 

*   **Industrial Gas Turbines:**    

*   Transition ducts and combustion liners    

*   Hot gas path components    

*   Turbine shrouds and seals 

*   **Power Generation:

**    *   Advanced gas turbine components    

*   High-temperature fasteners and hardware 

*   **Industrial Processing:**    

*   Heat treatment fixtures and furnace components    

*   High-temperature valves and pumps 

*   **Medical Technology:

**    *   Specialized surgical implants    

*   Radiation therapy components 

 --- #### **7. Key Characteristics & Advantages

** *   **Exceptional High-Temperature Capability:

** Maintains mechanical properties up to 1100°C (2012°F) 

*   **Superior Oxidation Resistance:

** Outstanding performance in oxidizing atmospheres up to 1150°C (2100°F) 

*   **Excellent Creep Resistance:

** Maintains structural integrity under sustained loading at high temperatures 

*   **Outstanding Thermal Fatigue Resistance:

** Withstands repeated thermal cycling without degradation 

*   **Enhanced Fabricability:

** Good weldability and formability compared to many high-temperature alloys

 *   **Long-Term Microstructural Stability:

** Maintains properties during extended high-temperature exposure 

*   **Non-Magnetic Properties:

** Suitable for applications requiring magnetic transparency 

 --- **Disclaimer:

** *Udimet® is a registered trademark of Special Metals Corporation. The values provided are typical and for informational purposes only. For critical applications, always consult the official material data sheets from the supplier and relevant design codes.*

Packing of Alloy 188,Udimet 188,UNS R30188 

 Standard Packing: 

Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 1669 gallon liquid totes Special package is available on request.