Latrobe,Lescalloy® UT-18 VAC-ARC ; High Strength Alloy Steel Tube,Pipe

Latrobe Lescalloy® UT-18 VAC-ARC ; 1.25 in. round High Strength Alloy Steel Tube Product Information -:- For detailed product information, please contact sales. -: Latrobe Lescalloy® UT-18 VAC-ARC ; 1.25 in. round High Strength Alloy Steel Tube Synonyms -:- For detailed product information, please contact sales. -:

Latrobe Lescalloy® UT-18 VAC-ARC ; 1.25 in. round High Strength Alloy Steel Product Information -:- For detailed product information, please contact sales. -: # **Product Datasheet: Latrobe Lescalloy® UT-18 VAC-ARC High Strength Alloy Steel (1.25" Round Bar)** ## **Executive Summary** Latrobe Lescalloy® **UT-18 VAC-ARC** is a specialized **ultra-high strength managing steel** supplied in a premium **1.25-inch (31.75 mm) round bar** form, refined via the **Vacuum Arc Remelting (VAR)** process. Engineered to deliver an exceptional combination of **extreme tensile strength (>300 ksi) and good fracture toughness**, UT-18 utilizes a unique **nickel-cobalt-molybdenum martensitic age-hardening system**. The **VAC-ARC refinement** and controlled **1.25-inch diameter** format ensure optimal through-section homogeneity and consistent, predictable mechanical properties, making it ideal for mission-critical, high-stress aerospace and defense components. --- ## **Material Technology & Processing** **Managing Steel Metallurgy:** UT-18 belongs to the 18% Nickel Maraging steel family (300-grade), achieving its properties through a low-temperature aging process rather than conventional quench-and-temper: 1. **Solution Annealing:** Forms a soft, low-carbon martensite. 2. **Machining/Forming:** Performed in the soft, annealed condition. 3. **Age Hardening:** Precipitation of intermetallic compounds (Ni₃Mo, Ni₃Ti) within the martensitic matrix produces extreme strength with minimal distortion. **VAC-ARC & 1.25" Round Bar Advantages:** - **Optimal Diameter:** The 1.25" size is ideal for a wide range of high-performance shafts, pins, fasteners, and actuators, balancing high-strength capability with excellent hardenability depth. - **Superior Purity:** VAR processing drastically reduces inclusions and gases (O, H, N), directly enhancing **fatigue life, stress corrosion cracking (SCC) resistance, and transverse ductility**. - **Uniform Response:** Ensures consistent aging kinetics and mechanical properties from surface to center of the bar. - **Minimal Distortion:** The aging process at ~900°F (482°C) allows for near-net-shape hardening with excellent dimensional stability. --- ## **Chemical Composition (Typical Weight %)** *Precise balance for martensitic transformation and age-hardening response.* | Element | Content Range (%) | Metallurgical Function | |---------|------------------|------------------------| | **Nickel (Ni)** | 18.0 - 19.0 | Primary alloying element; enables formation of soft, lath martensite and provides age-hardening via intermetallic formation. | | **Cobalt (Co)** | 8.0 - 9.0 | Reduces solubility of Molybdenum in the matrix, driving precipitation hardening. | | **Molybdenum (Mo)** | 4.5 - 5.2 | Key precipitation hardening element; forms Ni₃Mo intermetallics during aging. | | **Titanium (Ti)** | 0.50 - 0.80 | Forms Ni₃Ti precipitates, contributing significantly to strength. | | **Aluminum (Al)** | 0.05 - 0.15 | Deoxidizer; forms minor hardening precipitates. | | **Carbon (C)** | ≤ 0.030 | Kept ultra-low to ensure martensite toughness and weldability. | | **Manganese (Mn)** | ≤ 0.10 | Residual. | | **Silicon (Si)** | ≤ 0.10 | Residual. | | **Sulfur (S)** | ≤ 0.010 | Minimized for ductility. | | **Phosphorus (P)** | ≤ 0.010 | Minimized for toughness. | | **Iron (Fe)** | Balance | Matrix. | *Note: Ultra-low carbon and precise control of Ti, Al, and Mo are critical for consistent aging response in the 1.25" section.* --- ## **Physical & Mechanical Properties** ### **Guaranteed Minimum Mechanical Properties (1.25" Round, Aged Condition)** | Property | Longitudinal Direction | Units | Test Standard | |----------|------------------------|--------|----------------| | **Tensile Strength** | 300 min | ksi (2070 MPa) | ASTM E8 | | **0.2% Yield Strength** | 285 min | ksi (1965 MPa) | ASTM E8 | | **Elongation (in 2")** | 8 min | % | ASTM E8 | | **Reduction in Area** | 35 min | % | ASTM E8 | | **Hardness** | 54 - 57 | HRC | ASTM E18 | ### **Typical/Enhanced Properties (VAC-ARC Premium)** | Property | Typical Value | Notes | |----------|---------------|--------| | **Tensile Strength** | 305 - 320 | ksi | | **Fracture Toughness (K_Ic)** | 70 - 90 | ksi√in (77 - 99 MPa√m) *Exceptional for this strength level* | | **Charpy V-Notch Impact** | 20 - 30 | ft-lb | | **Fatigue Endurance Limit** | ~ 110 - 120 | ksi (10⁷ cycles, R= -1) *Superior to conventional quench & temper steels* | | **Modulus of Elasticity** | 26.5 x 10⁶ | psi (183 GPa) | ### **Solution Annealed Condition (For Fabrication)** - **Hardness:** 28 - 32 HRC - **Tensile Strength:** ~ 150 ksi (1035 MPa) - **Machinability:** Good (approx. 50% of 1212 steel) ### **Physical Constants** | Property | Value | Units | |----------|-------|--------| | **Density** | 0.290 | lb/in³ (8.03 g/cm³) | | **Coefficient of Thermal Expansion** | 5.9 x 10⁻⁶ | /°F (70-600°F) | | **Thermal Conductivity** | 12.0 | BTU·in/(hr·ft²·°F) at 212°F | --- ## **International Standards & Specifications** UT-18 VAC-ARC 1.25" round conforms to the highest industry standards for premium maraging steels. ### **Primary Aerospace & Defense Specifications** - **AMS 6514:** Steel Bars, Forgings, and Tubing, 18Ni Maraging 300 (0.03C max) Vacuum Melted. *(Primary governing spec)*. - **MIL-S-46850 (INT):** Maraging Steel Plate, Sheet, Strip, Bar, and Forgings, 18 Percent Nickel Alloy, 280 and 300 ksi Yield Strength. - **ASTM A538:** Standard Specification for 18 Percent Nickel Maraging Steel Plate, Sheet, and Strip (Grade 300). ### **Quality & Testing Compliance (VAR-Premium)** - **AMS 2301:** Premium Aircraft Quality Steel Cleanliness ("Fineness Rating A" typical for VAR). - **ASTM E1019:** Determination of Carbon, Sulfur, and Nitrogen. - **ASTM E45:** Assessment of Inclusion Content (Stringent limits). - **Internal Latrobe PQ Spec:** Exceeds standard AMS requirements for ultrasonic quality and mechanical property consistency in bar product. --- ## **Product Applications** The 1.25" round bar form factor makes UT-18 VAC-ARC ideal for high-strength, rotational, or axial load components. ### **Aerospace & Defense** - **Rocket Motor Cases & Actuators:** High-pressure vessels and piston rods for thrust vector control. - **Aircraft Landing Gear Components:** High-strength pins, bolts, and torque links. - **Helicopter Rotor Systems:** Pitch change shafts, spindle bolts. - **Missile & Ordnance Components:** Guidance system housings, warhead cases, safing/arming device shafts. - **Fasteners & Pins:** Specialized high-strength bolts, clevis pins, and shear pins for critical joints. ### **High-Performance Industrial & Racing** - **High-Pressure Valve Components:** Stem shafts and stems for extreme service. - **Precision Tooling:** Shafts for high-load dies, ejector pins, and mold components. - **Motorsports:** Lightweight, high-strength suspension components (tie rods, pushrods), drive shafts, and gearbox shafts. ### **Special Applications** - **Scanning & Imaging Equipment:** High-stiffness, non-magnetic shafts and stages (low magnetic permeability). - **Prototype & R&D Components:** For applications requiring the ultimate strength-to-weight ratio in a machinable bar stock. --- ## **Manufacturing & Fabrication Guidelines** ### **Standard Heat Treatment Cycle** 1. **Solution Anneal:** 1500°F ±25°F (816°C ±14°C) for 1 hour per inch of thickness, air cool or furnace cool. Results in soft, machinable condition. 2. **Age Harden:** 900°F ±10°F (482°C ±6°C) for 3-6 hours, air cool. *This is the critical strengthening step.* ### **Machining (Solution Annealed Condition)** - **Excellent Machinability:** Softer and more consistent than hardened conventional steels. - **Tooling:** Use positive rake, sharp carbide tools. - **Coolant:** Use heavy-duty soluble oil for best results. - **Distortion:** Minimal during subsequent aging. ### **Welding** - **Weldable** using matching or overmatching maraging steel filler wire (e.g., ER18Ni300). - **Requires post-weld solution anneal and re-aging** for full strength restoration in the HAZ. - **Gas Tungsten Arc Welding (GTAW)** is preferred. ### **Quality Assurance for 1.25" Round Bar** - **Full Ultrasonic Testing (UT):** Per ASTM A388/AMS 2631 for internal quality. - **Mechanical Testing:** From both end and mid-length locations of the bar lot. - **Chemistry Certification:** With traceability to the VAR heat. - **Surface Quality:** Centerless ground or turned to precise tolerances (typically h9/h11). --- ## **Available Specifications for 1.25" Round** | Parameter | Specification | |-----------|---------------| | **Diameter** | 1.250" ±0.005" (31.75 mm) | | **Straightness** | ≤ 0.010" per foot | | **Condition** | Solution Annealed & Descaled (Ready for machining and aging) | | **Length** | Standard 12' (144") or cut-to-length per order | | **Surface Finish** | 32 µin (0.8 µm) Ra or better, typical | --- ## **Technical Support** Latrobe provides comprehensive support for UT-18 VAC-ARC applications: - **Aging Cycle Optimization** for specific section sizes. - **Machining and Grinding Recommendations.** - **Welding Procedure Specification (WPS) Development.** - **Failure Analysis and Component Life Assessment.** --- **Disclaimer:** This datasheet provides characteristic information for UT-18 VAC-ARC in 1.25" round bar form. For final design and procurement, consult official Latrobe Specialty Metals technical data sheets and engage with their application engineering team. Properties are dependent on exact adherence to the recommended heat treatment. This material is subject to International Traffic in Arms Regulations (ITAR) controls. -:- For detailed product information, please contact sales. -: Latrobe Lescalloy® UT-18 VAC-ARC ; 1.25 in. round High Strength Alloy Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6459 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. -: Latrobe Lescalloy® UT-18 VAC-ARC ; 1.25 in. round High Strength Alloy Steel Properties -:- For detailed product information, please contact sales. -:

Applications of Latrobe Lescalloy® UT-18 VAC-ARC ; 1.25 in. round High Strength Alloy Steel Tube -:- For detailed product information, please contact sales. -: Chemical Identifiers Latrobe Lescalloy® UT-18 VAC-ARC ; 1.25 in. round High Strength Alloy Steel Tube -:- For detailed product information, please contact sales. -:

Packing of Latrobe Lescalloy® UT-18 VAC-ARC ; 1.25 in. round High Strength Alloy Steel Tube -:- 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 Tube 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 2930 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