Maraging 250,Udimar 250 Bar(Round bar, Flat bar),,E FORU

British Specs:BS S162，American Specs:AMS 6512 Bar, Tube, Forgings AMS 6520 Sheet, Strip and Plate ASTM A646 MIL-S-46850 Type 3，German Specs:WS 1.6359

### **Product Datasheet: Maraging Steel 250 / Udimar 250 Bar (Round & Flat Bar)** --- #### **1. Product Overview** **Maraging Steel 250 Bar** (commercially known as **Udimar 250 Bar**) is supplied in both round bar and flat bar configurations, providing versatile stock material for manufacturing critical components requiring ultra-high strength and excellent toughness. This martensitic age-hardening steel offers superior mechanical properties with minimal distortion during heat treatment, making it ideal for precision components in aerospace, defense, and tooling industries. The availability in both round and flat forms enables optimal material selection for various design requirements and machining strategies. --- #### **2. Chemical Composition (Weight %)** | Element | Min (%) | Max (%) | Balance | |---------|----------|----------|---------| | **Nickel (Ni)** | 17.00 | 19.00 | - | | **Cobalt (Co)** | 7.00 | 8.50 | - | | **Molybdenum (Mo)** | 4.50 | 5.20 | - | | **Titanium (Ti)** | 0.30 | 0.50 | - | | **Aluminum (Al)** | 0.05 | 0.15 | - | | **Iron (Fe)** | - | - | Balance | | **Carbon (C)** | - | 0.03 | - | | **Manganese (Mn)** | - | 0.10 | - | | **Silicon (Si)** | - | 0.10 | - | | **Sulfur (S)** | - | 0.01 | - | | **Phosphorus (P)** | - | 0.01 | - | --- #### **3. Physical & Mechanical Properties** **A. Mechanical Properties (After Solution Annealing & Aging)** - **Tensile Strength:** 1,720 - 1,790 MPa (250 - 260 ksi) - **Yield Strength (0.2% Offset):** 1,655 - 1,725 MPa (240 - 250 ksi) - **Elongation:** 10 - 14% - **Reduction in Area:** 45 - 55% - **Hardness:** 48 - 52 HRC - **Fracture Toughness (K_Ic):** 70 - 90 MPa√m - **Impact Toughness (Charpy V):** 25 - 35 J **B. Physical Properties** - **Density:** 8.00 g/cm³ (0.289 lb/in³) - **Modulus of Elasticity:** 185 GPa (26.8 × 10⁶ psi) - **Poisson's Ratio:** 0.30 - **Thermal Conductivity:** 19.0 - 21.0 W/m·K - **Thermal Expansion Coefficient:** 10.5 - 11.0 × 10⁻⁶/°C (20 - 100°C) - **Electrical Resistivity:** 0.60 - 0.65 μΩ·m **C. Bar Specifications** **Round Bar:** - **Diameter Range:** 5 mm - 300 mm (0.2" - 12") - **Diameter Tolerance:** h11 standard, tighter tolerances available - **Straightness:** ≤ 1.5 mm/m - **Surface Finish:** Turned, ground, or polished **Flat Bar:** - **Thickness Range:** 5 mm - 150 mm (0.2" - 6") - **Width Range:** 20 mm - 300 mm (0.8" - 12") - **Thickness Tolerance:** ±0.1 mm to ±0.5 mm - **Width Tolerance:** ±0.5 mm to ±1.0 mm --- #### **4. Product Applications** **Round Bar Applications:** - **Aircraft landing gear** components and actuators - **Rocket motor case** segments and closures - **Precision shafts** and spindle components - **High-strength fasteners** and special bolts - **Die-casting** machine components **Flat Bar Applications:** - **Aircraft structural** brackets and fittings - **Tooling plates** and mold bases - **Fixture components** and machine frames - **Defense vehicle** structural members - **Precision ground** stock for machining **Common Applications for Both Forms:** - **Injection molding** machine components - **Extrusion press** rams and stems - **Helicopter rotor** system components - **Racing engine** connecting rods and parts - **Optical mounting** systems and instruments --- #### **5. International Standards & Specifications** | Standard Body | Specification Number | Title/Description | |---------------|----------------------|-------------------| | **AMS** | AMS 6512 | Steel Bars, Forgings, and Tubing 18Ni (250) | | **ASTM** | A538 | Standard Specification for Precipitation-Hardening Steel | | **UNS** | K92890 | Unified Numbering System Designation | | **MIL** | MIL-S-46850 | Steel, Maraging 250 Grade | | **ISO** | 683-13 | Heat-treatable steels, alloy steels, and free-cutting steels | | **DIN** | 1.6358 | Material designation for X2NiCoMo18-8-5 | --- #### **6. Heat Treatment Process** **Solution Annealing (Before Machining)** - **Temperature:** 820 ± 10°C (1,508 ± 18°F) - **Time:** 1 hour per 25 mm of thickness/diameter - **Cooling:** Air cool to room temperature - **Resulting Hardness:** 28-32 HRC **Aging Treatment (After Machining)** - **Temperature:** 480 ± 5°C (896 ± 9°F) - **Time:** 3-6 hours depending on section size - **Cooling:** Air cool to room temperature - **Final Hardness:** 48-52 HRC --- #### **7. Machining & Fabrication** **Machining Guidelines:** - **Optimal Condition:** Machine in solution-annealed state - **Tooling:** Carbide tools with positive rake angles - **Speeds & Feeds:** Moderate to high speeds with adequate coolant - **Threading:** Excellent results with proper tool geometry **Fabrication Advantages:** - **Minimal Distortion:** During heat treatment - **Good Machinability:** In annealed condition - **Weldability:** Excellent with proper procedures - **Surface Finish:** Achieves excellent final finish --- #### **8. Quality Assurance** **Standard Testing:** - **Chemical Analysis:** Certified ladle and product analysis - **Mechanical Testing:** Tensile and impact tests from samples - **Ultrasonic Testing:** Available for critical applications - **Dimensional Verification:** Certified to specified tolerances **Quality Certifications:** - **Material Traceability:** Full documentation provided - **Surface Quality:** Free from harmful defects - **Heat Treatment Certification:** When supplied in aged condition - **Compliance:** Meets all relevant international standards --- **Packaging & Delivery:** - Protective packaging to prevent damage - Clear identification and heat number marking - Custom cutting services available - Just-in-time delivery options **Contact Information:** [Your Company Information] *Note: All mechanical properties are typical for material in the fully aged condition. Properties may vary based on specific section size and heat treatment parameters. Consult our technical team for application-specific recommendations.*

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 2575 gallon liquid totes Special package is available on request.