Maraging 250,Udimar 250,,E FORU

### **Maraging 250 / Udimar 250** **Ultra-High Strength Nickel-Maraging Steel for Critical Aerospace Applications** --- #### **1. Overview** **Udimar 250**, commercially known as **Maraging 250**, is an ultra-high strength, low-carbon nickel-maraging steel that achieves its exceptional properties through a unique age-hardening process of martensitic transformation. This alloy belongs to the 18Ni maraging steel family and is designed to provide an outstanding combination of ultra-high strength, excellent fracture toughness, and good fabricability. Unlike conventional high-strength steels, Maraging 250 gains its strength from intermetallic precipitation during aging rather than carbon hardening, resulting in superior mechanical properties and reduced distortion during heat treatment. --- #### **2. Chemical Composition (Weight %)** The typical chemical composition of Maraging 250 is outlined below. The balance is Iron (Fe). | Element | Content (%) | Key Function | | :--- | :--- | :--- | | **Iron (Fe)** | Balance | Forms the martensitic matrix structure. | | **Nickel (Ni)** | 17.0 - 19.0 | Primary element enabling martensitic transformation and intermetallic precipitation. | | **Cobalt (Co)** | 7.0 - 8.5 | Enhances the formation of intermetallic compounds and increases strength. | | **Molybdenum (Mo)** | 4.5 - 5.2 | Principal precipitation hardening element forming Ni₃Mo intermetallics. | | **Titanium (Ti)** | 0.3 - 0.5 | Forms Ni₃Ti precipitates contributing to secondary hardening. | | **Aluminum (Al)** | 0.05 - 0.15 | Aids in deoxidation and forms hardening precipitates. | | **Carbon (C)** | 0.03 max | Kept extremely low to improve toughness and weldability. | | **Manganese (Mn)** | 0.10 max | Controlled to minimize impurity effects. | | **Silicon (Si)** | 0.10 max | Controlled to minimize impurity effects. | | **Sulfur (S)** | 0.010 max | Kept at minimal levels to prevent hot shortness. | | **Phosphorus (P)** | 0.010 max | Minimized to prevent embrittlement. | | **Boron (B)** | 0.003 max | Trace addition to enhance hardenability. | --- #### **3. Physical Properties** | Property | Value / Condition | | :--- | :--- | | **Density** | 8.08 g/cm³ (0.292 lb/in³) | | **Melting Point** | ~ 1410 - 1450 °C (2570 - 2640 °F) | | **Modulus of Elasticity (Young's Modulus)** | 185 GPa (26.8 x 10⁶ psi) | | **Poisson's Ratio** | 0.30 | | **Thermal Conductivity** | 20.0 W/m·K (139 Btu·in/hr·ft²·°F) at 20°C | | **Mean Coefficient of Thermal Expansion** | 20 - 200°C: **10.5 x 10⁻⁶/°C** (5.8 x 10⁻⁶/°F) | | **Electrical Resistivity** | 0.65 μΩ·m at 20°C | --- #### **4. Mechanical Properties (Typical for Aged Condition - 480°C/900°F)** | Property | Value at Room Temperature | | :--- | :--- | | **Tensile Strength** | 1725 - 1795 MPa (250 - 260 ksi) | | **Yield Strength (0.2% Offset)** | 1655 - 1725 MPa (240 - 250 ksi) | | **Elongation (in 50 mm / 2 in)** | 8 - 10% | | **Reduction of Area** | 40 - 45% | | **Fracture Toughness (K_Ic)** | 70 - 90 MPa√m | | **Hardness** | 48 - 50 HRC | | **Charpy V-Notch Impact** | 20 - 25 J (15 - 18 ft-lb) | --- #### **5. International Standards** Maraging 250 conforms to the following international specifications: * **AMS:** * **AMS 6512:** Steel Bars, Forgings, and Tubing, Maraging 18Ni (250) * **ASTM:** * **A538:** Standard Specification for Maraging Steel Bars, Plates, and Forgings * **MIL:** * **MIL-S-46850:** Maraging Steel Plate, Sheet, and Strip * **Aerospace Standards:** * Various proprietary specifications from aerospace manufacturers --- #### **6. Product Applications** Maraging 250 is utilized in the most demanding aerospace and defense applications: * **Aerospace Structures:** * Rocket motor cases and missile bodies * Aircraft landing gear components * Space vehicle structural members * Helicopter rotor hubs * **Defense Systems:** * Weapon system components * Armor plate applications * Military aircraft critical parts * **Tooling and Manufacturing:** * High-performance die casting tools * Precision molds and fixtures * Extrusion rams and components * **Specialty Applications:** * High-performance racing components * Critical fasteners and bolts * Nuclear reactor components --- #### **7. Key Characteristics & Advantages** * **Ultra-High Strength:** Exceptional strength-to-weight ratio with yield strength exceeding 1655 MPa (240 ksi) * **Excellent Fracture Toughness:** Superior toughness compared to conventional high-strength steels at equivalent strength levels * **Good Fabricability:** Can be machined and formed in the solution-annealed condition * **Minimal Distortion:** Low thermal expansion and simple heat treatment minimize dimensional changes * **Superior Weldability:** Excellent welding characteristics without preheating or post-weld heat treatment requirements * **Simple Heat Treatment:** Age hardening at 480°C (900°F) provides consistent, reproducible properties * **Good Corrosion Resistance:** Better resistance to stress corrosion cracking than conventional high-strength steels * **Proven Reliability:** Extensive successful use in critical aerospace applications for decades --- **Disclaimer:** *Udimar is a registered trademark. 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. Proper solution treatment and aging cycles are essential for achieving optimal mechanical properties.*

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 1695 gallon liquid totes Special package is available on request.