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Zirconium Fasteners
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Titanium Countersunk Socket Head Cap Screw
Titanium Countersunk Socket Head Cap Screw

Titanium Fasteners

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Description

Titanium fasteners are high-performance mechanical joining components manufactured from commercially pure titanium or titanium alloys. They are widely used in aerospace, marine, offshore, chemical processing, power generation, medical, and high-end industrial assemblies due to their combination of:

  • High specific strength (excellent strength-to-weight ratio)

  • Outstanding corrosion resistance (especially in seawater and chloride environments)

  • Non-magnetic behavior (for most titanium grades)

  • Good fatigue resistance (especially α-β alloys such as Ti-6Al-4V / Grade 5 & Grade 23)

  • Service capability in aggressive media (Grade 7/12 in chemical environments)

Titanium fasteners include (but are not limited to): hex bolts, socket head cap screws, studs, nuts, washers, threaded rods, set screws, machine screws, and special engineered fasteners.

2) Materials & Titanium Grade System

Titanium fasteners are produced primarily from:

A) Commercially Pure Titanium (CP Ti)

Used when maximum corrosion resistance and formability are required.

  • Grade 1: Softest, highest ductility, best cold formability, excellent corrosion resistance

  • Grade 2: “Workhorse” CP grade, balance of strength and corrosion resistance

B) Titanium Alloys

Used for higher strength, higher temperature, or enhanced corrosion resistance.

  • Grade 5 (Ti-6Al-4V): Most common titanium alloy for fasteners; high strength, good fatigue performance

  • Grade 23 (Ti-6Al-4V ELI): Extra-low interstitial version of Grade 5; improved fracture toughness and ductility (often medical/aerospace)

  • Grade 7 (Ti-0.2Pd): CP titanium with palladium; superior corrosion resistance in reducing acids/crevice conditions

  • Grade 9 (Ti-3Al-2.5V): Medium strength, excellent formability; often tubing/fasteners where ductility matters

  • Grade 12 (Ti-0.3Mo-0.8Ni): Enhanced corrosion resistance + good high-temperature stability; good in crevice/chloride environments

Important note on “Grade 12”: It is less common for commodity bolts than Grade 2/5/7/23 but used in chemical and marine equipment when specified.

3) Applicable Material Standards (Most Common)

Titanium fastener raw material (bar/wire/rod) is typically produced and certified to one or more of the following:

ASTM (widely used)

  • ASTM B348 — Titanium and titanium alloy bars and billets (common for bolts/studs)

  • ASTM B863 / B265 — depending on product forms (wire/sheet/plate, as applicable)

  • ASTM F67 — CP titanium for surgical implant applications (medical, when required)

  • ASTM F136 — Ti-6Al-4V ELI (Grade 23) for surgical implant applications

AMS (Aerospace Material Specifications, common in aerospace fasteners)

  • Various AMS specifications exist for Ti alloys and processing routes; aerospace fasteners often require AMS materials and tightly controlled processing/traceability.

ISO / EN / DIN (international)

  • ISO 5832 series (medical implant alloys, where applicable)

  • EN / DIN titanium material standards depending on region and contract requirements

4) Fastener Product Standards (Geometry / Dimensions)

Titanium fasteners typically follow the same dimensional standards as steel fasteners; material changes, geometry standards remain:

Metric fasteners (common)

  • ISO 4014 / ISO 4017 — Hex head bolts (partial thread / full thread)

  • ISO 4762 — Hex socket head cap screws

  • ISO 4032 — Hex nuts

  • ISO 7089 / ISO 7090 / ISO 7091 — Washers (plain washers variants)

  • ISO 898-1 is for carbon steel property classes (not directly titanium), but sometimes referenced for geometry/threads; titanium properties must be specified separately.

Inch fasteners (Unified, common in aerospace/industrial)

  • ASME B18 series — bolts, screws, studs, nuts, washers

  • Common aerospace hardware may follow NAS / MS / AN standards (depending on program requirements)

5) Thread Standards & Tolerances

Titanium fasteners can be manufactured with:

Metric threads

  • ISO metric threads: M1.6–M64 (or larger by design)

  • Thread pitch: coarse / fine per ISO

  • Tolerances commonly: 6g (external) and 6H (internal) unless specified otherwise

Unified threads (inch)

  • UNC / UNF / UNEF (e.g., 1/4-20 UNC, 1/4-28 UNF)

  • Aerospace may require UNJF / UNJ profiles

  • Tolerances: Class 2A/2B, 3A/3B (aerospace often Class 3)

Critical titanium thread note (galling)

Titanium has a high tendency to gall (adhesive wear), especially in Ti-on-Ti threaded joints. Best practices include:

  • Specifying anti-galling coatings or surface treatments

  • Using appropriate lubricants / anti-seize compounds

  • Avoiding Ti nut + Ti bolt combinations unless engineered against galling

6) Dimensions / Size Range (Typical Industrial Supply)

Titanium fasteners are available in many standard sizes; typical supply ranges (varies by manufacturer):

Metric

  • Diameter: M2 to M36 (stock), M42–M64 (project-based)

  • Length: 4 mm to 300 mm (stock), longer for studs/rods

Inch

  • Diameter: #0 to 1″ (stock), larger sizes by order

  • Length: 1/8″ to 12″ (stock), longer for studs/rods

Typical head styles

  • Hex head, hex flange, socket cap, button head, countersunk (flat), pan head, set screw, custom head forms

7) Mechanical Properties (Professional Spec Language)

Mechanical properties depend on grade, product form, and heat treatment condition. In professional documentation, properties are specified by the governing standard (ASTM/AMS/ISO) and certified on MTR/EN10204-type documents.

General guidance:

  • Grade 1 / 2: Lower strength, maximum ductility, excellent corrosion resistance

  • Grade 5 / 23: High strength, excellent fatigue, widely used for structural fasteners

  • Grade 7 / 12: Focus on corrosion resistance in aggressive chemical environments (strength varies)

  • Grade 9: Intermediate strength with good cold workability

For procurement-grade detail, mechanical requirements should be stated as:
“Material shall conform to ASTM B348 (Grade X), with mechanical properties per the same standard for the specified size and condition; test certificates required.”

8) Heat Treatment / Condition

Depending on grade:

  • CP titanium (Grade 1/2/7): usually supplied annealed or in specified condition

  • Grade 5 / Grade 23: can be supplied annealed or solution treated and aged depending on fastener design requirements

  • Grade 9 / 12: typically annealed, though processing routes may vary

For aerospace or safety-critical assemblies, specifications may require:

  • Defined thermal cycles

  • Lot traceability

  • Additional nondestructive testing (NDT)

9) Corrosion Resistance & Compatibility

Titanium fasteners provide excellent corrosion resistance in:

  • Seawater / marine atmosphere

  • Many chlorides

  • Oxidizing acids (grade-dependent)

  • Wet chlorine environments (grade-dependent)

Grade 7 is especially valued where crevice corrosion and reducing acid resistance is critical.

Galvanic corrosion note

When titanium contacts other metals (e.g., aluminum, carbon steel, copper alloys) in an electrolyte, galvanic effects may occur. Mitigation methods:

  • Electrical isolation (washers/bushings)

  • Coatings

  • Proper joint design and sealants

10) Surface Finish, Coatings & Anti-Galling Options

Common surface conditions:

  • As-machined

  • Pickled / passivated

  • Polished

  • Shot peened (when fatigue enhancement is specified)

  • Anodized (sometimes for identification, not primarily for corrosion)

Anti-galling / friction control (application-dependent):

  • Solid film lubricants

  • Specialized coatings engineered for titanium threads

  • Controlled lubrication during assembly is often mandatory

11) Marking, Traceability, Quality Documentation

Professional supply requirements often include:

  • Grade identification and/or manufacturer marking (where size allows)

  • Heat/lot number traceability

  • Mill Test Report (MTR) with chemical composition and mechanical test results

  • Inspection documents: EN 10204 3.1 (or 3.2 when required)

  • Dimensional inspection per ISO/ASME standards

  • Optional: PMI (Positive Material Identification), hardness testing, microstructure verification

12) Typical Applications by Grade (Common Engineering Practice)

  • Grade 1: chemical equipment, heat exchangers (low stress), corrosion-first applications

  • Grade 2: marine hardware, industrial fasteners, general corrosion-resistant assemblies

  • Grade 5 (Ti-6Al-4V): aerospace structures, motorsport, high-strength industrial joints

  • Grade 23 (ELI): aerospace critical parts and medical devices; improved toughness vs Grade 5

  • Grade 7: chemical processing, desalination, chloride + crevice risk environments

  • Grade 9: applications needing better formability than Grade 5 with stronger-than-CP performance

  • Grade 12: offshore/chemical equipment with crevice/chloride concerns and temperature stability needs