ATI Allvac® VascoMax® C-250 Specialty Steel Wire

ATI Allvac® VascoMax® C-250 Specialty Steel Wire, Heat Treatment: 927°C (1700°F) + Age Product Information -:- For detailed product information, please contact sales. -: ATI Allvac® VascoMax® C-250 Specialty Steel Wire, Heat Treatment: 927°C (1700°F) + Age Synonyms -:- For detailed product information, please contact sales. -:

ATI Allvac® VascoMax® C-250 Specialty Steel, Heat Treatment: 927°C (1700°F) + Age Product Information -:- For detailed product information, please contact sales. -: # ATI Allvac® VascoMax® C-250 Specialty Steel ## Premium Cobalt-Nickel Maraging Steel | Heat Treated to 927°C + Aged --- ### **Product Overview** ATI Allvac® VascoMax® C-250 (often designated as **C-250 or C250**) is a **high-cobalt, nickel-maraging steel** belonging to the elite family of **ultra-high-strength, low-carbon martensitic steels**. It is engineered to achieve an exceptional combination of **ultra-high strength (Yield Strength > 1725 MPa / 250 ksi), excellent fracture toughness, and good stress corrosion cracking resistance**. The specified heat treatment of **austenitizing at 927°C (1700°F) followed by precipitation aging** develops its peak properties, making it a premier material for the most demanding aerospace, defense, and tooling applications where **maximum strength-to-weight ratio and reliability under extreme stress are paramount**. --- ### **Chemical Composition (Weight %)** | Element | Min (%) | Max (%) | Typical (%) | Primary Function | |---------|---------|---------|-------------|------------------| | **Nickel (Ni)** | 18.0 | 19.0 | 18.5 | Forms the tough, ductile lath martensite matrix. Essential for base toughness. | | **Cobalt (Co)** | **11.5** | **12.5** | **12.0** | **Critical Driver.** Maximizes the supersaturation of Mo in martensite, providing an immense thermodynamic driving force for precipitation hardening, enabling strength > 250 ksi YS. | | **Molybdenum (Mo)** | 4.6 | 5.2 | 4.9 | Primary precipitation hardener; forms fine, coherent Ni₃(Mo, Ti) intermetallic particles. | | **Titanium (Ti)** | **2.8** | **3.1** | **3.0** | **Key Differentiator.** Very high Ti content compared to other grades (e.g., ~0.65% in 18Ni-300). Forms abundant Ni₃Ti precipitates, contributing massively to strength. | | **Aluminum (Al)** | 0.05 | 0.15 | 0.10 | Deoxidizer; minor precipitation contributor. | | **Carbon (C)** | — | 0.03 | ≤0.01 | Kept at ultra-low levels to maximize toughness and weldability. | | **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)** | — | 0.01 | ≤0.005 | Impurity control. | | **Phosphorus (P)** | — | 0.01 | ≤0.005 | Impurity control. | | **Iron (Fe)** | Balance | — | — | Base element. | **Core Metallurgical Identity:** This is a **true maraging steel** (low-carbon, Fe-Ni martensite hardened by intermetallic precipitation), distinguished by its **very high titanium (3.0%)** and **high cobalt (12.0%)** content, placing its strength level between the standard **18Ni-2500 and 18Ni-300 (350) grades**. --- ### **Recommended Heat Treatment** 1. **Austenitizing (Solution Treatment):** * **Temperature:** **927°C (1700°F)** ± 15°C * **Time:** 1 hour per inch of thickness (minimum 1 hour), then **Air Cool**. * **Purpose:** Fully austenitizes the material, dissolves all precipitates, and produces a uniform, soft lath martensite upon cooling (~30 HRC). 2. **Aging (Precipitation Hardening):** * **Temperature:** **482°C (900°F)** ± 5°C * **Time:** 3-6 hours (typically 3 hours for sections < 25mm, longer for heavier sections), then **Air Cool**. * **Phenomenon:** Fine, coherent intermetallic precipitates (Ni₃Ti, Ni₃Mo) form uniformly within the martensite matrix, dramatically increasing strength while retaining good toughness. --- ### **Mechanical Properties (After 927°C Austenitize + Aged)** *Typical minimum or average values in peak-aged condition (Longitudinal).* | Property | Typical Value Range | Test Standard | Notes | |----------|-------------------|---------------|-------| | **0.2% Yield Strength (YS)** | **1725 - 1790 MPa (250 - 260 ksi)** | ASTM E8 | Nominal: **1725 MPa (250 ksi)**. | | **Ultimate Tensile Strength (UTS)** | 1790 - 1900 MPa (260 - 276 ksi) | ASTM E8 | | | **Elongation (in 50 mm)** | 8 - 12% | ASTM E8 | Good ductility for this strength level. | | **Reduction of Area (RA)** | 35 - 50% | ASTM E8 | | | **Hardness** | 50 - 54 HRC | ASTM E18 | | | **Fracture Toughness (K_IC)** | **55 - 75 MPa√m** | ASTM E399 | **Excellent toughness for its strength class.** Superior to higher-strength grades like 18Ni-350. | | **Modulus of Elasticity** | 185 - 190 GPa (26.8 - 27.5 x 10⁶ psi) | ASTM E111 | | | **Fatigue Strength (10⁷ cycles, R=0.1)** | ~550 - 650 MPa | ASTM E466 | Highly surface-finish sensitive. | --- ### **Physical Properties (Aged Condition)** | Property | Value (at 20°C) | |----------|------------------| | **Density** | ~8.03 g/cm³ | | **Melting Range** | ~1400-1430°C (2550-2610°F) | | **Thermal Conductivity** | 18 - 20 W/m·K | | **Coefficient of Thermal Expansion** | 10.5 - 11.0 x 10⁻⁶/°C (20-100°C) | | **Electrical Resistivity** | ~0.7 μΩ·m | | **Magnetic Properties** | Ferromagnetic (martensitic). | --- ### **Key Characteristics & Advantages** * **Optimal Ultra-High-Strength Balance:** Provides a superior combination of **strength (250+ ksi YS) and fracture toughness** compared to other steels in this strength regime. * **Excellent Fabricability (in Annealed State):** Can be readily machined, formed, and welded in the solution-annealed condition (~30 HRC). * **Simple, Low-Distortion Aging:** The final hardening step (482°C aging) causes minimal dimensional change (~0.06%) and requires no quenching, simplifying heat treatment of complex parts. * **Good Stress Corrosion Cracking (SCC) Resistance:** Inherently more resistant to SCC in aggressive environments than many other ultra-high-strength steels. * **High Strength-to-Weight Ratio:** Enables significant weight savings in critical structural components. --- ### **International Standards & Common Designations** VascoMax C-250 is a proprietary alloy with well-established specifications. | Standard/System | Designation | Title / Notes | |----------------|-------------|---------------| | **Aerospace Material Spec (AMS)** | **AMS 6521 (Type 3)** | Historically referenced. Specific procurement is often to a **Source Control Drawing (SCD)** or the following AMS. | | **Aerospace Material Spec (AMS)** | **AMS 6517** | *Steel, Maraging, 18.5Ni - 12.5Co - 4.8Mo - 1.4Ti (0.10Al) (0.020C)*. This is a common specification for the 250 ksi grade, though chemistry may vary slightly. | | **Proprietary/Trade Name** | **ATI Allvac VascoMax C-250**, **Marval C250** | Primary commercial names. | | **Unified Numbering System (UNS)** | **K92890** (shared with other 18Ni grades) | Requires additional specification of chemistry/strength level. | | **Military Standard** | **MIL-S-46850** | May be invoked, specifying the 250 ksi grade. | --- ### **Primary Applications** C-250 is specified for **mission-critical, weight-sensitive structural components** across aerospace and defense. 1. **Aerospace (Primary Application):** * **Rocket and Missile Motor Cases** (solid and liquid fuel) for launch vehicles and strategic systems. * **Aircraft Landing Gear Components:** Critical forgings for main struts, beams, and pistons in high-performance military and commercial aircraft. * **Helicopter Rotor Hubs and Drive Shafts.** * **Spacecraft and Satellite Structures,** fittings, and deployment mechanisms. 2. **Defense & Ordnance:** * **Gun Barrel Components** (e.g., recoil cylinders, breech rings). * **Armor Vehicle Components.** * **High-Strength Fasteners and Bolts** for primary structure. 3. **Tooling & High-Performance Equipment:** * **Extrusion Dies and Mandrels** for titanium and superalloys. * **Die Inserts for High-Pressure Die Casting.** * **Components for Isostatic Pressing (HIP) Tooling.** * **High-Load Shafts and Spindles** in specialized machinery. --- ### **Fabrication & Processing Guidelines** * **Machining:** All complex and heavy machining should be performed in the **solution-annealed condition**. Machining in the aged state is difficult and requires CBN or premium carbide tooling. * **Forming:** All significant forming operations must be completed in the annealed state. * **Welding:** Use Gas Tungsten Arc Welding (GTAW/TIG) with a **matching filler metal** (e.g., similar cobalt-nickel maraging grade). **Post-Weld Heat Treatment (PWHT)** is **mandatory** for critical applications and consists of a full re-solution treatment (927°C) followed by aging. * **Heat Treatment:** Precise temperature control (±5°C) during aging is critical for consistent properties. * **Corrosion Protection:** **Not stainless.** Requires protective coatings such as **electroless nickel, cadmium plating, or specialized paint systems**. Plated components require **baking** to avoid hydrogen embrittlement. --- ### **Comparison with Other High-Strength Grades** | Feature | VascoMax C-250 (~250 ksi YS) | 18Ni-300 (~300 ksi YS) | 4340M (~260 ksi YS) | |---------|------------------------------|------------------------|---------------------| | **Strengthening** | Precipitation (Intermetallic) | Precipitation (Intermetallic) | Quench & Temper (Carbides) | | **Toughness (KIC)** | **Excellent** | Good | Moderate to Low | | **Aging Distortion** | Very Low | Very Low | High (Quench Distortion) | | **Fabricability (Annealed)** | Excellent | Excellent | Good | | **Weldability** | Good (with PWHT) | Good (with PWHT) | Poor | | **Key Advantage** | **Best Toughness at 250 ksi** | **Higher Strength** | **Lower Cost** | --- ### **Summary** **ATI Allvac® VascoMax® C-250**, processed via the **927°C (1700°F) austenitize and 482°C (900°F) age** cycle, represents the **gold standard for ultra-high-strength applications demanding exceptional toughness**. Its optimized chemistry, centered on high cobalt and very high titanium, delivers a **unique property set that prioritizes reliability and damage tolerance** at the 250 ksi yield strength level. While the **18Ni-300 (350) grade offers higher ultimate strength, C-250 is often the preferred choice for fracture-critical components** where a higher safety margin against crack propagation is essential. It is a proven, reliable material that has enabled some of the most advanced achievements in aerospace and defense engineering, offering an outstanding balance of extreme performance and manufacturing practicality. -:- For detailed product information, please contact sales. -: ATI Allvac® VascoMax® C-250 Specialty Steel, Heat Treatment: 927°C (1700°F) + Age Specification Dimensions Size： Diameter 20-1000 mm Length <7361 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® C-250 Specialty Steel, Heat Treatment: 927°C (1700°F) + Age Properties -:- For detailed product information, please contact sales. -:

Applications of ATI Allvac® VascoMax® C-250 Specialty Steel Wire, Heat Treatment: 927°C (1700°F) + Age -:- For detailed product information, please contact sales. -: Chemical Identifiers ATI Allvac® VascoMax® C-250 Specialty Steel Wire, Heat Treatment: 927°C (1700°F) + Age -:- For detailed product information, please contact sales. -:

Packing of ATI Allvac® VascoMax® C-250 Specialty Steel Wire, Heat Treatment: 927°C (1700°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 3832 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