Hastelloy alloy 188,1

### **Introduction to Hastelloy® Alloy 188 and Related Specifications** **Hastelloy® Alloy 188** is a cobalt-chromium-nickel-tungsten wrought superalloy known for its exceptional combination of high-temperature strength, outstanding resistance to oxidation and sulfidation, and excellent fabricability. The addition of Lanthanum (La) significantly enhances its stability and oxidation resistance for prolonged service at extreme temperatures. It is a solution-strengthened alloy, meaning its properties are derived from the solid solution of its alloying elements, not from precipitation hardening. This alloy is covered by several key international standards for its base metal form (sheet, plate, bar) and for welding consumables used to join it. --- ### **1. Base Metal: Hastelloy® Alloy 188** The wrought forms of Alloy 188, such as sheet, plate, and bar, are primarily governed by aerospace material specifications (AMS) from SAE International. #### **Key Standards for Base Metal:** * **AMS 5755:** Covers bars, forgings, and rings. * **AMS 5786:** Covers welding wire. * **AMS 5787:** Covers sheet, strip, and plate. #### **Chemical Composition (Weight %, typical per AMS specifications):** | Element | Minimum | Maximum | | :--- | :--- | :--- | | **Chromium (Cr)** | 20.0 | 24.0 | | **Nickel (Ni)** | 20.0 | 24.0 | | **Cobalt (Co)** | Balance | --- | | **Tungsten (W)** | 13.0 | 15.0 | | **Iron (Fe)** | --- | 3.0 | | **Manganese (Mn)** | 1.0 | 2.0 | | **Silicon (Si)** | --- | 0.40 | | **Lanthanum (La)** | 0.02 | 0.12 | | **Carbon (C)** | 0.05 | 0.15 | | **Boron (B)** | --- | 0.015 | | **Sulfur (S)** | --- | 0.015 | | **Phosphorus (P)** | --- | 0.04 | *Balance is Cobalt, along with incidental impurities.* #### **Physical Properties (Typical):** * **Density:** 9.13 g/cm³ (0.330 lb/in³) * **Melting Range:** 1330 - 1380 °C (2425 - 2515 °F) * **Electrical Resistivity:** 98.4 μΩ·cm at 21°C * **Thermal Expansion Coefficient:** 12.3 μm/m·°C (20-100°C) * **Thermal Conductivity:** 10.1 W/m·K at 100°C * **Modulus of Elasticity (Young's Modulus):** 242 GPa (35 x 10⁶ psi) at 21°C #### **Mechanical Properties (Typical at Room Temperature per AMS 5787 - Sheet):** * **Tensile Strength:** ≥ 965 MPa (140 ksi) * **Yield Strength (0.2% Offset):** ≥ 485 MPa (70 ksi) * **Elongation:** ≥ 35% *Note: Properties can vary with product form and thermal treatment.* --- ### **2. Welding Consumables: ERCoCr-A and ECoCr-A** To weld Hastelloy Alloy 188 and similar high-temperature alloys, matching-composition welding electrodes and wires are used. These are standardized by the American Welding Society (AWS) and the American Society of Mechanical Engineers (ASME). #### **Key Standards for Welding Consumables:** * **AWS A5.14 / ASME SFA-5.14:** Specification for Nickel and Nickel-Alloy Bare Welding Electrodes and Rods. * **Product:** **ERCoCr-A** (Bare welding wire for GTAW/TIG, GMAW/MIG, SAW processes). * **AWS A5.11 / ASME SFA-5.11:** Specification for Nickel and Nickel-Alloy Welding Electrodes for Shielded Metal Arc Welding. * **Product:** **ECoCr-A** (Covered electrodes for SMAW/Stick welding). #### **Chemical Composition of Welding Products (Weight %, AWS Requirements):** The composition for ERCoCr-A and ECoCr-A is very similar to the base alloy, with slight adjustments for weldability. | Element | ERCoCr-A / ECoCr-A (AWS A5.14/A5.11) | | :--- | :--- | | **Cobalt (Co)** | Balance | | **Chromium (Cr)** | 19.0 - 23.0 | | **Nickel (Ni)** | 9.0 - 11.0* | | **Tungsten (W)** | 13.0 - 16.0 | | **Iron (Fe)** | 3.0 max | | **Manganese (Mn)** | 1.0 - 2.0 | | **Silicon (Si)** | 0.10 - 0.50 (0.75 max for ECoCr-A) | | **Lanthanum (La)** | 0.20 - 0.50 | | **Carbon (C)** | 0.05 - 0.15 | *\*Note: The Ni content in the weld metal is specified lower than in the base metal to maintain a stable austenitic microstructure and prevent cracking.* --- ### **Product Applications** Hastelloy Alloy 188 is designed for service in the most demanding high-temperature and corrosive environments. Its primary applications include: * **Aerospace & Gas Turbines:** * Combustion cans and liners * Afterburner components * Turbine seals and spray bars * Hot section casings * **Industrial Gas Turbines:** * Transition ducts * Combustion chambers * **Heat Treating Equipment:** * Furnace fixtures, radiant tubes, and muffles * **Chemical Processing:** * Components exposed to severe sulfidizing atmospheres * **Biomedical:** Used in certain high-performance prosthetic devices due to its biocompatibility and wear resistance. --- ### **Summary of International Standards** | Product Form | Standard | Governing Body | Designation | | :--- | :--- | :--- | :--- | | **Sheet, Plate, Strip** | AMS 5787 | SAE International | Hastelloy Alloy 188 | | **Bar, Forging, Ring** | AMS 5755 | SAE International | Hastelloy Alloy 188 | | **Welding Wire** | AMS 5786 | SAE International | Hastelloy Alloy 188 | | **Bare Welding Wire** | AWS A5.14 / ASME SFA-5.14 | American Welding Society / ASME | **ERCoCr-A** | | **Covered Electrodes** | AWS A5.11 / ASME SFA-5.11 | American Welding Society / ASME | **ECoCr-A** | **Note:** "Hastelloy" is a registered trademark of Haynes International, Inc. The specifications mentioned are industry standards used to define the technical requirements for procurement and quality assurance.

Packing of 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 3254 gallon liquid totes Special package is available on request.