Premium Ti-38-644 Bar – AMS 4957 | Powerful Beta-C Titanium Rod

Description

🏆 Premium Ti-38-644 Bar – AMS 4957 | Powerful Beta-C Titanium Alloy Rod

This page provides an in‑depth, engineering‑grade introduction to Ti-38-644 Bar produced to AMS 4957. To help engineers and buyers evaluate and specify the alloy quickly, we include composition, microstructure, properties, heat treatment, processing guidance, QA/inspection, dimensional programs, and application notes. Throughout the page we keep the terms Ti-38-644 Bar and AMS 4957 visible so the content is easy to find and rank.

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✨ Executive Summary

Ti-38-644 Bar (Ti‑3Al‑8V‑6Cr‑4Mo‑4Zr), widely known as Beta‑C near‑beta titanium, offers a rare combination of very high strength, good fracture toughness, excellent fatigue performance, and useful hardenability in bar and forging stock. When supplied in accordance with AMS 4957, Ti-38-644 Bar delivers predictable mechanical properties and tight chemistry suitable for critical aerospace and high‑performance industrial service. Compared with α‑β staples like Ti‑6Al‑4V, Ti-38-644 Bar enables higher design allowables and more aggressive weight reduction in landing gear, fasteners, and load‑bearing members.

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🔑 Why Choose It

• High specific strength: With density ~4.82 g/cm³, Ti-38-644 Bar in STA condition reaches strengths that rival high‑strength steels at a fraction of the weight.
• Fracture and fatigue: The near‑beta microstructure of Ti-38-644 Bar supports high fracture toughness and excellent fatigue limits, essential in AMS 4957 aerospace bars.
• Hardenability and process window: Ti-38-644 Bar responds strongly to solution treatment and aging (STA), allowing property tailoring for thick and thin sections.
• Corrosion and temperature: Better general corrosion resistance than high‑strength steels; stable mechanical response across common aerospace temperature windows.
• Traceability: AMS 4957 controls chemistry, cleanliness, and mechanical testing for repeatable lot‑to‑lot performance.

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🧪 Alloy Identity & Nomenclature

• Formal designation: Ti‑3Al‑8V‑6Cr‑4Mo‑4Zr
• Informal / trade: Beta‑C titanium
• Product form here: Ti-38-644 Bar to AMS 4957 (bars, forgings, forging stock)
• UNS style references: Near‑beta Ti family (context for specifiers)

Ti-38-644 Bar is intentionally balanced with β‑stabilizers (V, Cr, Mo) and Zr for solid‑solution strengthening; Al contributes to α stability and creep resistance in mixed structures. Within AMS 4957, chemistry windows and melting practice keep the alloy inside the target β field for predictable heat‑treat response.

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⚙️ Chemical Composition (Typical for AMS 4957)

Element	Typical wt%	Function
Ti	Bal.	Matrix
Al	~3.0	Strength, creep, α stabilization
V	~8.0	β stabilization, strength
Cr	~6.0	β stabilization, corrosion, hardenability
Mo	~4.0	β stabilization, strength
Zr	~4.0	Solid‑solution strengthening, toughness

Note: Lot‑specific ranges follow AMS 4957; melt practice and cleanliness are critical to obtain the intended Ti-38-644 Bar properties.

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🧬 Microstructure & Metallurgy

Ti-38-644 Bar is a near‑β alloy. After solution treat + quench, the structure is largely metastable β with controlled α precipitation during aging. Key points for AMS 4957 bars:

• β transus typically in the 780–800 °C range (lot dependent). Processing near, below, or slightly above the transus tailors grain size and α precipitate morphology.
• Aging (480–595 °C) promotes fine α precipitation inside β, raising yield and UTS while preserving reasonable ductility.
• Section thickness effect: Compared with α‑β alloys, Ti-38-644 Bar maintains strength more uniformly through larger diameters due to improved hardenability.

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📊 Physical & Mechanical Properties (Reference Values)

• Density: ~4.82 g/cm³
• Elastic modulus: ~110–120 GPa
• Poisson’s ratio: ~0.33
• Thermal expansion (20–300 °C): ~8.5–9.3 ×10⁻⁶ /K
• Thermal conductivity: ~6–8 W/m·K (temperature dependent)

Representative Room‑Temperature Mechanical Properties (STA):

• UTS: ~1240–1380 MPa (size/condition dependent for AMS 4957)
• 0.2% YS: ~1100–1250 MPa
• Elongation: ~10–15%
• Reduction of area: ~20–30%
• Hardness: typically 36–42 HRC (converted), depending on aging schedule

These figures illustrate why designers select Ti-38-644 Bar over conventional α‑β grades when AMS 4957 strength and reliability are required.

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🔥 Heat Treatment

Goal: Achieve target strength/fatigue without over‑aging.

Common STA route for Ti-38-644 Bar:

1. Solution Treat: 730–790 °C (below or near β transus), hold based on diameter.
2. Quench: Water or fast air to retain β.
3. Age: 480–595 °C for 8–24 h; lower temperature → higher strength; higher temperature → better ductility/toughness.

Notes for AMS 4957:

• Verify β transus for each heat; use Jominy or equivalent response data if available.
• For thick Ti-38-644 Bar, quench agitation and bath control improve uniformity.
• Consider double‑aging for demanding fatigue regimes.

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🧱 Forging & Hot Working Guidance

Ti-38-644 Bar forging stock per AMS 4957 is typically worked in 760–870 °C windows:

• Start in upper range for deformation; finish near lower range to refine grains.
• Avoid extended soaking above transus to prevent grain coarsening.
• Use controlled reductions per pass; reheat frequently to maintain window.

Cooling: Air cool to minimize oxygen pickup; maintain inert protection when feasible. Subsequent STA restores and elevates properties in finished Ti-38-644 Bar.

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🧰 Machining Recommendations

Ti-38-644 Bar machines similarly to other high‑strength near‑β alloys:

• Tooling: Sharp, positive‑rake carbide or advanced coated carbides; PVD coatings preferred to resist built‑up edge. For tight tolerances, CBN or ceramics in finishing.
• Speeds/feeds: Reduce surface speed vs steels; maintain moderate‑high feed to keep tools engaged. Generous coolant (emulsion or straight oil) is vital.
• Operations:
  • Turning: Low SFM, steady feed, minimal dwell.
  • Drilling: Split‑point or coolant‑through drills; peck cycles to break chips.
  • Milling: Climb milling, rigid fixturing; avoid rubbing.
• Burr control: Plan deburr steps; Ti can form tenacious burrs after heavy cuts.

With proper practices, Ti-38-644 Bar holds excellent finishes after turning/centerless grinding to AMS 4957 requirements.

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🧲 Welding & Joining

Ti-38-644 Bar is weldable with the right discipline:

• Processes: GTAW (TIG) and EBW are common; laser possible with tight shielding.
• Shielding: High‑purity Ar; meticulous trailing and backside shielding to avoid α‑case and embrittlement.
• Filler: Matching or compatible near‑β compositions.
• Post‑weld: Local or full heat treatment (solution + age) to recover strength; weld trials should bracket final properties for AMS 4957 compliance.

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🛡 Corrosion & Environmental Performance

• General corrosion: Significantly better than high‑strength steels in many environments.
• Chlorides: Typical titanium passivity; avoid crevice conditions when possible.
• Galvanic: When coupled to carbon steel or copper alloys in electrolytes, insulate or manage area ratios.
• Hydrogen: Prevent pickup during pickling/welding; follow AMS 4957 cleanliness and hydrogen limits for Ti-38-644 Bar.

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🏗 Applications

• Aerospace landing gear & attachment hardware requiring AMS 4957 pedigree
• High‑strength fasteners & fittings where Ti-38-644 Bar replaces tempered steels
• Engine pylons, hinge pins, actuators, and structural links
• Defense & offshore components needing high specific strength and durability

Each of these areas benefits from the STA response and toughness profile of Ti-38-644 Bar.

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📐 Dimensions, Tolerances & Finishes (Supply to AMS 4957)

• Diameter programs: 10–200 mm typical; other diameters on request for Ti-38-644 Bar.
• Lengths: Up to ~6 m (random) or cut‑to‑length; straightness per bar standards.
• Tolerances: Turned/ground and polished options to precise OD tolerances suited to AMS 4957.
• Surface: As‑forged, rough‑turned, or TG&P Ti-38-644 Bar; Ra targets available for bearing/fit applications.

We maintain full heat/lot traceability on every Ti-38-644 Bar.

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🔍 Quality Assurance & Testing

To satisfy AMS 4957, our Ti-38-644 Bar program includes:

• Melt practice: Controlled remelting routes; chemistry and cleanliness verified.
• Mechanical testing: Tensile at room (and when specified, elevated) temperatures.
• NDT: Ultrasonic testing to aerospace acceptance criteria for Ti-38-644 Bar.
• Microstructural review: Confirm grain size and α precipitation after STA.
• Documentation: EN 10204 3.1 (or 3.2 when agreed) MTC with heat number, results, and AMS 4957 statement of compliance.

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⚖️ Density & Weight Calculation

Use 4.82 g/cm³ for design estimates of Ti-38-644 Bar. For quick mass (kg) of round bars:

Mass=0.0000031416×d2(mm)×L(mm)×4.82\text{Mass} = 0.0000031416 \times d^2(\text{mm}) \times L(\text{mm}) \times 4.82

This simplifies quoting and logistics for Ti-38-644 Bar cut pieces.

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🧮 Property Tailoring via Heat Treatment

Because Ti-38-644 Bar is near‑β, modest heat‑treat changes yield big property shifts:

• Lower aging (≈480–520 °C): Maximizes strength of Ti-38-644 Bar, slightly reduces ductility.
• Higher aging (≈560–595 °C): Improves toughness and fatigue crack growth resistance.
• Duplex or double aging: Fine‑tunes fatigue for rotating hardware.

For AMS 4957 contracts, we record all furnace charts and quench parameters on the MFR file.

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🧩 Comparison with Other Titanium Alloys

• Vs Ti‑6Al‑4V: Ti-3Al-8V-6Cr-4Mo-4Zr  Bar reaches higher strength in large diameters; better hardenability; similar corrosion resistance.
• Vs Ti‑10V‑2Fe‑3Al (Ti‑1023): Comparable strength potential; Ti-3Al-8V-6Cr-4Mo-4Zr Bar often chosen for fracture/fatigue balance.
• Vs Ti‑5Al‑5V‑5Mo‑3Cr (Ti‑5553): Ti‑5553 is also near‑β; grade choice depends on availability and specific AMS requirements—AMS 4957 specifically covers Ti-3Al-8V-6Cr-4Mo-4Zr Bar.
• Vs high‑strength steels: Far lower density and no red‑rust; desirable for aerospace weight targets.

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🧼 Surface Conditioning & α‑Case Control

For Ti-38-644 Bar, α‑case forms if heated in oxygen. We mitigate via:

• Inert/clean furnace atmospheres and wraps
• Limited exposure times
• Post‑process machining or pickling to remove any α‑case before final inspection per AMS 4957

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🧯 Processing Hazards & Safety Notes

• Titanium fines can be combustible—control chips and dust from machining  Ti-3Al-8V-6Cr-4Mo-4Zr Bar.
• Use dedicated tooling and clean work areas to avoid cross‑contamination.
• Follow quench and furnace safety protocols rigorously.

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🧾 Ordering Guide

When requesting quotation per AMS 4957, include:

1. Alloy & form: “Ti-3Al-8V-6Cr-4Mo-4Zr Bar”
2. Standard: “AMS 4957”
3. Condition: As forged/turned or STA (solution treated & aged)
4. Dimensions: OD and cut length (or random)
5. Testing: UT, tensile frequency, any elevated‑temp tests
6. Documentation: EN 10204 3.1 (or 3.2), special approvals
7. End use: Aerospace/industrial (helps align inspection plans)

This ensures you receive Ti-38-644 Bar that meets your design intent and AMS 4957 obligations.

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📦 Packaging & Logistics

• Bar ends protected with caps; bundles strapped and tagged with heat/lot IDs.
• Corrosion‑inhibiting wraps as needed.
• Export crates for long Ti-3Al-8V-6Cr-4Mo-4Zr Bar lengths; ISPM‑15 pallets.
• Full documentation packet: COA/MTC + dimensional list + AMS 4957 statement.

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🧠 Engineering FAQ

Q1: Is Ti‑38‑644 the same as Beta‑C?
A: Yes. Ti-38-644 Bar is the Beta‑C composition (Ti‑3Al‑8V‑6Cr‑4Mo‑4Zr) supplied to AMS 4957.

Q2: What density should I use?
A: Use ~4.82 g/cm³ for it weight and inertia estimates.

Q3: Which heat‑treat gives the highest strength?
A: A lower‑temperature age after proper solution treat & quench typically yields the highest YS/UTS ; verify with your section size.

Q4: Can I weld this alloy?
A: Yes—with rigorous shielding and cleanliness. Post‑weld STA restores AMS 4957 properties.

Q5: How does it compare with Ti‑6Al‑4V?
A: Ti-38-644 Bar achieves higher strength in larger diameters and offers excellent fatigue; Ti‑6Al‑4V is more ubiquitous and easier to source fast.

Q6: Do you offer ultrasonic testing?
A: Yes. We UT inspect Ti-38-644 Bar to aerospace acceptance levels and record results on the MTC.

Q7: Can you supply short sample lengths?
A: Absolutely. We cut trial lengths of Ti-38-644 Bar for prototype builds, fully traceable to AMS 4957 lots.

Q8: Typical lead time?
A: Stock items ship quickly; for special diameters/conditions of it, allow time for forging/heat treat per AMS 4957.

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📈 Case Uses & Design Notes

• Landing gear pins: Replace steel pins with Ti-38-644 Bar to save weight while keeping safety margins, complying with AMS 4957.
• Actuator shafts & links: STA Ti-38-644 Bar sustains cyclic loads with favorable fatigue crack growth rates.
• Precision fasteners: Where high clamp load and corrosion resistance are required, Ti-38-644 Bar is a strong candidate.

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🔗 Related Products (Internal)

• GR5 Titanium Plate – Ti‑6Al‑4V sheet for aerospace & industrial
• TZM Molybdenum Rod – high‑temp strength for vacuum furnace fixtures

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📝 Summary for Buyers

If your project calls for high specific strength, consistent heat‑treat response, and aerospace pedigree, Ti-38-644 Bar to AMS 4957 is an excellent choice. We provide bar, forging stock, and cut lengths with full MTCs, UT, and documented STA cycles. Tell us your diameter, length, and inspection plan, and we will align the manufacturing route to your performance targets.

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📞 Contact Us

📧 Email: sales@niticu.com
📞 Phone / WhatsApp / WeChat: +86 13335373172
🏭 Factory: Baotai Road Industrial Park, High-tech Zone, Baoji City, Shaanxi, China
🌐 Website: https://niticu.com

📩 Contact us now for pricing, samples, and expert technical support — we respond within 24 hours.