P/M 625 Corrosion Resistant Alloy,UNS N06625,E FORU

### **P/M Alloy 625 (UNS N06625) - Nickel-Chromium-Molybdenum-Niobium Superalloy** #### **Overview** **P/M Alloy 625 (UNS N06625)** is the powder metallurgy (P/M) form of the renowned nickel-chromium-based superalloy, Alloy 625. This alloy is universally recognized for its exceptional combination of **high strength**, **outstanding corrosion resistance**, and **excellent fabricability**. While Alloy 625 is available in wrought forms (sheet, bar, tube), the P/M processing route involves gas atomization of the melt to produce a fine, spherical powder, which is then consolidated via **Hot Isostatic Pressing (HIP)** or other methods. This process yields a material with a fine, uniform, and isotropic microstructure, free from the chemical segregation that can occur in large cast ingots. This makes P/M 625 ideal for manufacturing near-net-shape components with highly consistent mechanical and corrosion-resistant properties in all directions. The alloy's strength is derived not from carbon, but from the solid solution hardening effects of molybdenum and niobium, and most importantly, from the precipitation of coherent gamma double prime (γ'') phases (Ni₃Nb) during aging. --- #### **Chemical Composition (Weight % - Typical)** The chemical composition of the P/M product is tightly controlled to match its wrought counterpart. | Element | Content (%) | | :--- | :--- | | **Nickel (Ni)** | **Balance** (≥ 58.0) | | **Chromium (Cr)** | **20.0 - 23.0** | | **Molybdenum (Mo)** | **8.0 - 10.0** | | **Niobium (Nb) [and Tantalum Ta]** | **3.15 - 4.15** | | **Iron (Fe)** | **≤ 5.0** | | **Aluminum (Al)** | **≤ 0.40** | | **Titanium (Ti)** | **≤ 0.40** | | **Carbon (C)** | **≤ 0.10** | | **Manganese (Mn)** | **≤ 0.50** | | **Silicon (Si)** | **≤ 0.50** | * **Nickel (Ni):** Provides the austenitic matrix and inherent resistance to corrosion and oxidation. * **Chromium (Cr):** Confers exceptional resistance to oxidizing environments and high-temperature scaling. * **Molybdenum (Mo):** Imparts resistance to non-oxidizing media (e.g., chlorides, sulfuric acid) and provides solid solution strengthening. * **Niobium (Nb):** The key strengthening element. It acts with molybdenum to reduce corrosion in welded zones and, in combination with nickel, forms the very effective **gamma double prime (γ'')** strengthening phase. --- #### **Physical & Mechanical Properties** The following table outlines the key properties of P/M Alloy 625, which are comparable to and often more isotropic than its wrought form. | Property | Value / Description | | :--- | :--- | | **Density** | 8.44 g/cm³ | | **Melting Range** | 1290 - 1350 °C (2350 - 2460 °F) | | **Thermal Conductivity** | 9.8 W/m·K (at 100°C) | | **Specific Heat (20°C)** | 410 J/kg·K | | **Mean Coefficient of Thermal Expansion** | 12.8 μm/m·°C (20-100°C) | | **Modulus of Elasticity** | 207 GPa (30.0 x 10⁶ psi) | | **Tensile Strength (HIP + Annealed)** | ~830 MPa (120 ksi) | | **Yield Strength (0.2% Offset, HIP + Annealed)** | ~410 MPa (60 ksi) | | **Elongation (HIP + Annealed)** | ~45% | | **High-Temperature Strength** | Excellent strength and oxidation resistance up to **980°C (1800°F)**. | --- #### **Key Characteristics & Applications** **Key Characteristics:** 1. **Exceptional Corrosion Resistance:** Excellent resistance to a wide range of severe corrosive environments, including pitting, crevice corrosion, and stress-corrosion cracking. It resists seawater, acidic and alkaline salts, and oxidizing acids. 2. **High Strength Without Heat Treatment:** Exhibits high strength and toughness in the annealed condition due to its unique strengthening mechanism. 3. **Excellent Fatigue & Thermal Fatigue Strength:** The fine, homogeneous P/M microstructure contributes to superior fatigue resistance. 4. **Oxidation Resistance:** Maintains a protective oxide layer at high temperatures, offering good resistance to scaling up to 1100°C. 5. **Isotropic Properties:** The P/M HIP process ensures properties are uniform in all directions, which is critical for complex-shaped components. **Typical Applications:** P/M Alloy 625 is used for high-integrity components across demanding industries. * **Aerospace:** Engine static parts, casings, rings, seals, and fabricated components requiring high strength-to-weight ratio and temperature resistance. * **Marine & Offshore:** Propeller blades, submarine fittings, seawater system components, and fasteners exposed to corrosive seawater. * **Chemical Processing:** Reactors, heat exchanger parts, valves, and pumps handling aggressive chemicals. * **Oil & Gas:** Downhole well components, blow-out preventer parts, and manifolds for sour service (H₂S environments). * **Power Generation:** Gas turbine components, heat exchangers, and ducting in both conventional and nuclear plants. --- #### **International Standards** P/M Alloy 625 is covered by several international standards, primarily from ASTM. | Product Form | ASTM (USA) | ASME (USA) | EN (European) | UNS | | :--- | :--- | :--- | :--- | :--- | | **Powder Preursor** | **ASTM B964** | - | - | N06625 | | **HIPed Billets & Shapes** | **ASTM B988** | - | **EN 10295 / NiCr22Mo9Nb** | N06625 | | **Forged Bar from P/M** | - | - | - | N06625 | **Important Note:** While the above standards specifically cover P/M forms, the alloy composition itself is identical to the well-established wrought UNS N06625, which is covered by standards like ASTM B443 (plate), B444 (tube), and B446 (bar). The choice of P/M is a manufacturing decision to achieve specific microstructural and geometric benefits. --- #### **Summary** In summary, **P/M Alloy 625 (UNS N06625)** leverages the superior chemical homogeneity and isotropy of powder metallurgy to deliver the renowned properties of Alloy 625 in a form ideal for complex, high-performance components. Its exceptional corrosion resistance, high strength across a broad temperature range, and excellent fatigue performance make it a material of choice for the most critical applications in aerospace, marine, and energy industries. The P/M route provides design engineers with a reliable method to produce near-net-shape parts with guaranteed property consistency.

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 3202 gallon liquid totes Special package is available on request.