ATI Allvac® VascoMax® T-250 Specialty Steel Wire

ATI Allvac® VascoMax® T-250 Specialty Steel Wire, Heat Treatment: 816°C (1500°F) + Age Product Information -:- For detailed product information, please contact sales. -: ATI Allvac® VascoMax® T-250 Specialty Steel Wire, Heat Treatment: 816°C (1500°F) + Age Synonyms -:- For detailed product information, please contact sales. -:

ATI Allvac® VascoMax® T-250 Specialty Steel, Heat Treatment: 816°C (1500°F) + Age Product Information -:- For detailed product information, please contact sales. -: # ATI Allvac® VascoMax® T-250 Specialty Steel ## High-Strength, High-Toughness 10Ni-8Co-4Cr Maraging Steel | Heat Treated to 816°C + Age --- ### **Product Overview** ATI Allvac® VascoMax® T-250 is a **10% Nickel - 8% Cobalt - 4% Chromium maraging steel** designed to achieve a nominal yield strength of **250 ksi (≈1725 MPa)**. Unlike the classic 18Ni maraging steels, the T-250 grade utilizes a **lower nickel, chromium-containing chemistry** that provides a distinct set of advantages: **superior fracture toughness at equivalent strength levels, excellent stress corrosion cracking (SCC) resistance, and enhanced hardenability for larger sections**. The specified heat treatment of **austenitizing at 816°C (1500°F) followed by precipitation aging** optimizes this alloy for applications requiring an **exceptional balance of strength, toughness, and environmental resistance**, particularly in large aerospace structural components. --- ### **Chemical Composition (Weight %)** | Element | Min (%) | Max (%) | Typical (%) | Metallurgical Function & Rationale | |---------|---------|---------|-------------|------------------------------------| | **Nickel (Ni)** | 9.0 | 10.0 | 9.5 | **Lower than 18Ni grades.** Sufficient to form a tough, low-carbon martensite. Reduces cost and improves weldability slightly. | | **Cobalt (Co)** | 7.5 | 8.5 | 8.0 | Drives molybdenum into precipitation; provides solid solution strengthening. Lower than C-250, reducing cost. | | **Chromium (Cr)** | **3.5** | **4.5** | **4.0** | **Key Differentiator.** Provides **markedly improved corrosion and oxidation resistance** compared to non-Cr maraging steels. Enhances hardenability. | | **Molybdenum (Mo)** | 4.0 | 5.0 | 4.5 | Primary precipitation hardener (forms Ni₃Mo, Fe₂Mo). | | **Titanium (Ti)** | 0.5 | 1.0 | 0.7 | Secondary precipitation hardener (forms Ni₃Ti). Level balanced for toughness. | | **Aluminum (Al)** | 0.05 | 0.15 | 0.10 | Deoxidizer. | | **Carbon (C)** | — | 0.03 | ≤0.01 | Ultra-low for maximum toughness. | | **Manganese (Mn)** | — | 0.10 | 0.05 | Residual. | | **Silicon (Si)** | — | 0.10 | 0.05 | Residual. | | **Boron (B)** | — | 0.005 | 0.003 | Enhances hardenability. | | **Zirconium (Zr)** | — | 0.02 | 0.01 | Grain refiner. | | **Sulfur (S)** | — | 0.010 | ≤0.005 | Impurity control. | | **Phosphorus (P)** | — | 0.010 | ≤0.005 | Impurity control. | | **Iron (Fe)** | Balance | — | — | Base element. | **Core Identity:** The **10Ni-8Co-4Cr** system distinguishes T-250 from the **18Ni-9Co-0Cr** system of VascoMax C-250. The addition of **4% Chromium** is transformative for environmental resistance. --- ### **Recommended Heat Treatment** 1. **Austenitizing (Solution Treatment):** * **Temperature:** **816°C (1500°F)** ± 10°C * **Time:** 1 hour per inch of thickness, then **Air Cool** or **Oil Quench** (for very thick sections > 150mm). * **Purpose:** The lower austenitizing temperature (vs. 927°C for 18Ni grades) is sufficient due to the lower nickel content, reducing energy cost and potential for grain growth. 2. **Aging (Precipitation Hardening):** * **Temperature:** **482°C (900°F)** ± 5°C * **Time:** 3-6 hours, then **Air Cool**. * **Metallurgical State:** Achieves peak strength through precipitation of intermetallic phases. The presence of Cr may lead to minor secondary carbide precipitation, contributing to stability. --- ### **Mechanical Properties (After 816°C Austenitize + Aged)** *Typical minimum guaranteed values in peak-aged condition (Longitudinal).* | Property | Minimum Guaranteed | Typical Achieved | Test Standard | Advantage vs. C-250 | |----------|-------------------|------------------|---------------|---------------------| | **0.2% Yield Strength (YS)** | 1655 MPa (240 ksi) | 1725 - 1790 MPa (250 - 260 ksi) | ASTM E8 | Slightly lower or comparable. | | **Ultimate Tensile Strength (UTS)** | 1725 MPa (250 ksi) | 1790 - 1860 MPa (260 - 270 ksi) | ASTM E8 | | | **Elongation (in 50 mm)** | 10% | 12 - 14% | ASTM E8 | **Superior ductility.** | | **Reduction of Area (RA)** | 50% | 55 - 65% | ASTM E8 | **Superior ductility.** | | **Hardness** | 48 HRC | 49 - 51 HRC | ASTM E18 | Slightly lower. | | **Fracture Toughness (K_IC)** | **100 MPa√m** | **110 - 130 MPa√m** | ASTM E399 | **Key Advantage: 30-50% higher than C-250.** | | **Modulus of Elasticity** | 180 GPa | 185 - 190 GPa | ASTM E111 | Similar. | | **Stress Corrosion Threshold (K_ISCC)** | **Report - Very High** | Significantly higher than non-Cr grades | ASTM E1681 | **Key Advantage due to 4% Cr.** | --- ### **Physical Properties (Aged Condition, 20°C)** | Property | Value | |----------|-------| | **Density** | ~8.00 g/cm³ | | **Thermal Conductivity** | 20 - 22 W/m·K | | **Coefficient of Thermal Expansion** | 10.5 - 11.5 x 10⁻⁶ /°C (20-100°C) | | **Electrical Resistivity** | ~0.65 μΩ·m | | **Magnetic Properties** | Ferromagnetic | --- ### **Key Characteristics & Advantages** * **Exceptional Fracture Toughness:** The standout feature. Offers **K_IC > 110 MPa√m** at 250 ksi YS, enabling robust damage-tolerant design. * **Excellent Stress Corrosion Cracking (SCC) Resistance:** The 4% Cr content provides inherent resistance to chloride-induced SCC, making it suitable for marine and high-humidity aerospace environments. * **Good General Corrosion/Oxidation Resistance:** Superior to standard maraging steels; can be used with less aggressive coating systems. * **Superior Hardenability:** The Cr and lower Ni content allow through-hardening of **very thick sections (up to 300mm/12 inches)** with air cooling, reducing quench cracking risk. * **Good Weldability:** The lower carbon equivalent and Cr content can improve weldability compared to some ultra-high-strength steels. --- ### **International Standards & Designations** This grade is covered under specific aerospace and proprietary standards. | Standard/System | Designation | Title / Notes | |----------------|-------------|---------------| | **Aerospace Material Spec (AMS)** | **AMS 6529** | Common specification for this alloy type. May specify 10Ni-8Co-2Cr-1Mo or similar variants; T-250 meets or exceeds its requirements. | | **Aerospace Material Spec (AMS)** | **AMS 6512** | Sometimes referenced for 10Ni-8Co-4Cr steels. | | **Proprietary/Trade Name** | **ATI Allvac VascoMax T-250** | Primary commercial name. | | **Military Standard** | May be called out in system-specific **MIL** standards. | | | **Common Reference** | **10Ni-8Co-4Cr Maraging Steel** | Descriptive industry name. | --- ### **Primary Applications** T-250 is selected for **large, critical structural components** where **toughness, reliability, and environmental resistance are as important as high strength.** 1. **Aerospace & Defense (Primary Use):** * **Large Aircraft Landing Gear Components:** Forgings for main beams, trucks, and pistons for commercial wide-body (e.g., Boeing 777, 787) and military transport aircraft. Its **thick-section hardenability and toughness are ideal.** * **Rocket Motor Casings and Launch Vehicle Structures** for heavy-lift applications. * **Helicopter Rotor Hubs and Drive Shafts.** * **Marine and Carrier-Based Aircraft Components** due to its superior SCC resistance. 2. **Energy & Industrial:** * **Components for High-Pressure Isostatic Presses (HIP).** * **Large Shafts and Rolls** in heavy machinery. * **Tooling for Large Composite Molding.** 3. **Marine & Offshore:** * **Critical Fasteners and Connectors** in offshore platforms and subsea systems. * **Components for Deep-Sea Exploration Vehicles.** --- ### **Fabrication & Processing Guidelines** * **Machining:** Excellent machinability in the annealed condition (~30 HRC). Softer than annealed 18Ni grades. * **Forming:** All forming should be done in the annealed state. * **Welding:** Use GTAW (TIG) with a **matching or over-matching filler metal** (e.g., similar 10Ni-8Co-Cr filler). Pre-heat is generally not required for thin sections. **Post-Weld Heat Treatment (PWHT)** is recommended for critical applications: re-solution treat at 816°C and re-age. * **Heat Treatment:** The lower austenitizing temperature (816°C) is an energy-saving advantage. Air cooling is sufficient for most sections, simplifying processing of large parts. * **Corrosion Protection:** While significantly better than non-Cr grades, it is **not stainless.** For harsh environments, **cadmium plating, electroless nickel, or high-performance paint systems** are still recommended. The improved base corrosion resistance provides better backup protection if the coating is damaged. --- ### **Comparison with VascoMax C-250 (18Ni-12Co)** | Feature | **VascoMax T-250** (10Ni-8Co-4Cr) | **VascoMax C-250** (18Ni-12Co) | |---------|-----------------------------------|--------------------------------| | **Yield Strength** | ~1725-1790 MPa | ~1725-1790 MPa | | **Fracture Toughness (KIC)** | **Very High (110-130 MPa√m)** | High (55-75 MPa√m) | | **SCC Resistance** | **Excellent (Due to 4% Cr)** | Good | | **Hardenability** | **Excellent (Air hardens >300mm)** | Good (Air hardens ~150mm) | | **Austenitizing Temp** | **Lower (816°C / 1500°F)** | Higher (927°C / 1700°F) | | **Relative Cost** | **Lower (Less Ni & Co)** | Higher | | **Typical Use** | **Large, tough structures (Landing Gears)** | High-performance fittings, cases | --- ### **Summary** **ATI Allvac® VascoMax® T-250**, processed via **816°C (1500°F) austenitize and age**, is the **premier choice for engineering large, ultra-high-strength components that cannot afford to fail.** Its **10Ni-8Co-4Cr chemistry** represents an optimized alternative to the classic 18Ni maraging steels, trading a small amount of absolute strength potential for **dramatic gains in fracture toughness, environmental resistance, and thick-section capability.** It is the material that enables the **safe, reliable, and efficient design of mega-structures** like main landing gears for the world's largest aircraft, where the consequences of brittle fracture are catastrophic. For engineers seeking the **ultimate in damage tolerance and reliability at the 250 ksi strength level**, particularly in large cross-sections or aggressive environments, T-250 is the unequivocal technical leader. -:- For detailed product information, please contact sales. -: ATI Allvac® VascoMax® T-250 Specialty Steel, Heat Treatment: 816°C (1500°F) + Age Specification Dimensions Size： Diameter 20-1000 mm Length <7364 mm Size:We can customized as required Standard： Per your request or drawing We can customized as required Properties（Theoretical） Chemical Composition -:- For detailed product information, please contact sales. -: ATI Allvac® VascoMax® T-250 Specialty Steel, Heat Treatment: 816°C (1500°F) + Age Properties -:- For detailed product information, please contact sales. -:

Applications of ATI Allvac® VascoMax® T-250 Specialty Steel Wire, Heat Treatment: 816°C (1500°F) + Age -:- For detailed product information, please contact sales. -: Chemical Identifiers ATI Allvac® VascoMax® T-250 Specialty Steel Wire, Heat Treatment: 816°C (1500°F) + Age -:- For detailed product information, please contact sales. -:

Packing of ATI Allvac® VascoMax® T-250 Specialty Steel Wire, Heat Treatment: 816°C (1500°F) + Age -:- For detailed product information, please contact sales. -: Standard Packing: -:- For detailed product information, please contact sales. -: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and Steel Wire 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 3835 gallon liquid totes Special package is available on request. E FORUs’ is carefully handled to minimize damage during storage and transportation and to preserve the quality of our products in their original condition