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Titanium Grade 5 (Ti-6Al-4V) Technical Material Specification

Comprehensive technical specification for Titanium Grade 5 (Ti-6Al-4V) covering properties, Canadian stock sizing, machinability, defects, and handling for industrial fabrication and machining operations.

Material Overview & Common Uses

Titanium Grade 5 (Ti-6Al-4V) is the most widely used titanium alloy, accounting for approximately 50% of all titanium tonnage globally. It is an alpha-beta alloy containing 6% aluminum and 4% vanadium, offering an exceptional strength-to-weight ratio, excellent corrosion resistance, and good fatigue properties up to 400°C. In Canadian fabrication and machining environments, Ti-6Al-4V is the default choice for aerospace structural components (landing gear, airframe brackets), medical implants (hip stems, bone screws), high-performance automotive parts (connecting rods, valve springs), marine hardware (propeller shafts, heat exchangers), and chemical processing equipment. Its combination of high tensile strength (typically 900–1000 MPa) and low density (4.43 g/cm³) makes it indispensable where weight savings are critical. However, its poor thermal conductivity (7.2 W/m·K) and high chemical reactivity at elevated temperatures present significant machining challenges, requiring specialized tooling and coolant strategies.

Core Technical Properties & Sizing

Property / Category	Value / Specification
Density	4.43 g/cm³ (0.160 lb/in³)
Tensile Strength (Ultimate)	950–1050 MPa (138–152 ksi) per ASTM B265 / AMS 4911
Yield Strength (0.2% offset)	880–920 MPa (128–133 ksi)
Elongation at Break	10–14% in 2 inches (50 mm)
Modulus of Elasticity	114 GPa (16.5 × 10⁶ psi)
Hardness	Rockwell C 33–38 (as-annealed); up to C 42 after heat treatment
Thermal Conductivity	7.2 W/m·K at 20°C (very low – causes heat buildup in cutting zone)
Coefficient of Thermal Expansion	8.6 × 10⁻⁶ /°C (20–100°C)
Electrical Resistivity	1.7 × 10⁻⁶ Ω·m
Melting Range	1604–1660°C (2920–3020°F)
Corrosion Resistance	Excellent in seawater, chloride solutions, and oxidizing acids; susceptible to crevice corrosion in reducing environments above 80°C
Standard Canadian Stock Sizing (Sheet/Plate)
Sheet	0.025″ (0.64 mm), 0.032″ (0.81 mm), 0.040″ (1.02 mm), 0.050″ (1.27 mm), 0.063″ (1.60 mm), 0.080″ (2.03 mm), 0.090″ (2.29 mm), 0.100″ (2.54 mm), 0.125″ (3.18 mm) – common widths 48″ (1219 mm) and 60″ (1524 mm), lengths 96–144″ (2438–3658 mm)
Plate	0.1875″ (4.76 mm), 0.250″ (6.35 mm), 0.375″ (9.53 mm), 0.500″ (12.7 mm), 0.625″ (15.9 mm), 0.750″ (19.1 mm), 1.000″ (25.4 mm) – widths up to 72″ (1829 mm), lengths up to 240″ (6096 mm)
Round Bar (drawn or rolled)	1/8″ (3.18 mm) up to 12″ (304.8 mm) diameter, typically in 12′ (3.66 m) random lengths
Hex Bar	3/8″ (9.53 mm) to 2″ (50.8 mm) across flats
Tube (seamless)	1/4″ (6.35 mm) OD to 6″ (152.4 mm) OD, wall thicknesses 0.028″ (0.71 mm) to 0.500″ (12.7 mm)
Tolerances (per ASTM B265)
Thickness	±0.005″ for sheet <0.125″; ±0.010″ for plate 0.125–0.250″; ±0.015″ for plate >0.250″
Width	+1/4″ / -0″ for sheared edges; +1/2″ / -0″ for plasma or laser cut
Length	+1/2″ / -0″ for sheared; +1″ / -0″ for plasma/laser
Flatness	1/4″ in any 36″ for plate up to 0.500″ thick; 3/8″ in 36″ for thicker plate
Camber	1/8″ in any 8′ of length

Machinability, Tooling & Feeds

Parameter	Recommendation / Specification
Tool Material	Use uncoated or AlTiN-coated carbide (ISO K10–K20) for general turning/milling; CBN or PCD for finishing passes on hardened material (above 40 HRC). Avoid HSS except for low-speed drilling.
Cutting Speeds (Turning)	30–60 m/min (100–200 SFM) for roughing; 60–90 m/min (200–300 SFM) for finishing. Reduce speeds by 20–30% for interrupted cuts.
Feed Rates (Turning)	0.10–0.30 mm/rev (0.004–0.012 in/rev) for roughing; 0.05–0.15 mm/rev (0.002–0.006 in/rev) for finishing.
Depth of Cut	1–4 mm (0.040–0.160 in) for roughing; 0.2–0.5 mm (0.008–0.020 in) for finishing. Avoid light cuts (<0.1 mm) to prevent work hardening.
Milling	Climb milling preferred; use 50–80 m/min (160–260 SFM) with chip loads of 0.05–0.15 mm/tooth (0.002–0.006 in/tooth). Radial engagement should be >50% of tool diameter to avoid rubbing.
Drilling	Use short, rigid drills with 118–135° point angle and split point geometry. Speeds: 10–20 m/min (33–66 SFM); feed: 0.05–0.15 mm/rev (0.002–0.006 in/rev). Peck drilling (0.5–1× diameter per peck) is mandatory to clear chips and prevent heat buildup.
Coolant	High-pressure (70–100 bar / 1000–1500 psi) water-soluble coolant with 5–8% concentration directed at the cutting zone. For deep hole drilling, use oil-based cutting fluid. Flood coolant alone is insufficient; through-spindle coolant is highly recommended.
Threading	Use single-point threading with carbide inserts; speeds 20–30 m/min (65–100 SFM). For taps, use spiral point or spiral flute taps with TiCN coating; speeds 5–10 m/min (16–33 SFM).
Grinding	Use silicon carbide or CBN wheels; avoid aluminum oxide which loads quickly. Use light passes (0.01–0.02 mm) with copious coolant.
Welding	Requires inert gas shielding (argon or helium) with trailing shield for temperatures above 300°C. Pre-weld cleaning with acetone and stainless steel brush. Filler metal: ERTi-5 (same composition). Post-weld stress relief at 540–650°C for 1–4 hours in vacuum or inert atmosphere.
Heat Treatment	Solution treat at 900–950°C (1650–1740°F) for 1 hour, water quench, then age at 480–595°C (900–1100°F) for 4–8 hours to achieve ultimate tensile strength up to 1170 MPa.

Common Defects & Quality Control

Defect	Description	Detection / Prevention
Alpha Case	Oxygen-enriched surface layer (hard, brittle) formed during hot working or heat treatment in air. Must be removed by chemical milling (HF/HNO₃ pickle) or machining. Depth: 0.002–0.010″ (0.05–0.25 mm).	Microhardness testing or metallographic cross-section.
Microstructural Banding	Elongated alpha grains in a beta matrix due to improper forging or rolling. Reduces ductility and fatigue life.	Optical microscopy per ASTM E3. Acceptable banding per AMS 4928: no more than 2 ASTM grain size difference.
Porosity	Gas entrapment (hydrogen, nitrogen) during melting or welding. Can cause leaks in pressure vessels.	Radiographic (X-ray) per ASTM E1742 or ultrasonic per ASTM E2375. Maximum pore size: 0.5 mm for aerospace, 0.2 mm for medical implants.
Cracking	Hot cracking (solidification cracks) in welds or heat-affected zones; stress corrosion cracking in chloride environments above 80°C.	Dye penetrant (ASTM E1417) or magnetic particle (not applicable for non-ferrous).
Surface Contamination	Iron or carbon pickup from tooling or handling can cause localized corrosion or embrittlement.	EDX or Auger spectroscopy. Prevention: use dedicated stainless steel or titanium tools; avoid carbon steel contact.
Warpage	Distortion during heat treatment or machining due to residual stresses.	Stress relief before final machining is critical. Acceptable flatness: 0.010″ per foot for precision parts.
Inclusion	Non-metallic inclusions (oxides, nitrides) from raw material.	Ultrasonic immersion scanning per ASTM E2375. Maximum inclusion size: 0.1 mm for critical rotating parts.
Grain Size Variation	Mixed grain sizes (duplex structure) from improper annealing. Can cause inconsistent mechanical properties.	Inspection per ASTM E112. Acceptable: ASTM grain size 6–8 for most applications.
Hydrogen Embrittlement	Hydrogen pickup during pickling or welding leads to delayed cracking. Limit: <150 ppm for aerospace, <100 ppm for medical.	Vacuum fusion analysis per ASTM E1447.

Storage, Handling & Racking Guidelines

Category	Guideline / Specification
Storage Environment	Store in a clean, dry, temperature-controlled area (15–25°C, <50% RH). Avoid direct sunlight and proximity to chemical storage (acids, chlorides).
Racking	Use dedicated racks made of stainless steel or powder-coated carbon steel. Never store titanium directly on carbon steel racks – use plastic or rubber separators (e.g., 1/4″ thick polyethylene strips) to prevent galvanic corrosion. Rack spacing: minimum 6″ between sheets for air circulation.
Sheet/Plate Stacking	Maximum stack height: 12″ for sheets <0.125″ thick; 6″ for plates >0.500″ thick. Use interleaving paper (kraft or neutral pH) between sheets to prevent scratching. For long-term storage (>30 days), use VCI (Vapor Corrosion Inhibitor) paper.
Bar Stock	Store horizontally on V-shaped racks with support every 3′ to prevent sagging. For diameters >2″, use individual cradles. Never stack bars directly on top of each other – use wooden or plastic spacers.
Tube Storage	Store horizontally on racks with full-length support. Cap ends with plastic plugs to prevent debris ingress. Avoid stacking more than 3 layers high.
Handling	Always wear clean cotton or nitrile gloves – skin oils can cause staining and corrosion during subsequent heat treatment. Use lifting slings (nylon or polyester) for heavy plates; never use chains or wire ropes that can gouge the surface.
Cleaning	Before machining or welding, degrease with acetone or isopropyl alcohol using lint-free wipes. For heavy contamination, use alkaline cleaner (pH 9–11) followed by deionized water rinse. Never use chlorinated solvents (e.g., trichloroethylene) – they can cause stress corrosion cracking.
Inventory Management	Implement FIFO (First-In, First-Out) rotation. Tag each piece with heat number, thickness, and date received. Use Ryxen SupplyGrid to track real-time stock levels and auto-generate reorder points based on consumption rates and lead times (typically 6–12 weeks for mill orders).
Safety	Titanium fines and dust are pyrophoric – use wet machining or HEPA vacuum collection. Never allow dry titanium dust to accumulate. Store scrap in sealed metal containers with water cover. Ensure fire extinguishers are Class D (for metal fires).