Drawing No. EH–MT–025 // Engineering Materials
Titanium Alloy Properties
Reviewed September 2026
Ti-6Al-4V is the dominant alpha-beta titanium alloy and is used here as the titanium reference. It combines high specific strength and corrosion resistance with relatively low thermal conductivity and a modulus roughly half that of steel.
Representative properties
Switch units without changing the underlying material reference.
What changes these properties?
Engineering variability
- Strength varies with anneal, solution treatment, aging, product form and specification.
- Elastic modulus is much lower than steel despite high strength, so stiffness can govern.
- Thermal conductivity is low for a metal and temperature dependent.
- High-temperature oxidation, creep and fatigue require application-specific data.
Selection note
Strong choice for aerospace, chemical, marine and biomedical applications where corrosion resistance and specific strength justify higher material and fabrication cost.
Do not combine strength from one grade/condition with modulus, thermal data or temperature limits from another without checking compatibility. Where the overview shows a range, it is intended to expose variability—not establish allowable bounds.
Titanium in practice
Chosen for strength-to-weight and for corrosion resistance — two quite different arguments that lead to different grades.
Where it is specified
Two distinct markets. Structural: Ti-6Al-4V (Grade 5) in airframe fittings, engine fan blades and discs, landing gear components, fasteners, and orthopaedic implants — anywhere specific strength justifies the price.
Corrosion: commercially pure grades (Grade 1, 2) in heat exchangers, seawater piping, desalination plant, chlor-alkali and pulp bleaching equipment, where the material is chosen for its behaviour in oxidising chlorides rather than for strength.
The medical use rests on a third property: titanium's oxide film is biocompatible and osseointegrates, which no steel does.
Chosen over what
Against aluminium: twice the density but roughly twice the strength and usable to 400 °C rather than 150 °C. In airframes the two are used where each is better, not interchangeably.
Against steel: 40% less dense at comparable strength, and immune to seawater corrosion — but half the stiffness, which matters greatly for buckling and deflection-limited parts and is the reason titanium does not simply replace steel.
Against super-duplex or 6% Mo stainless in seawater: titanium is effectively immune to chloride pitting and stress-corrosion cracking, so for hot seawater heat exchangers it frequently wins on life-cycle cost despite higher purchase price.
How it fails
Galling and cold welding. Titanium seizes readily against itself and against many other metals; sliding contacts need coatings, anodising or dissimilar pairings. This is a design constraint, not a material defect.
Attack by reducing acids and by fluorides. Hydrofluoric acid dissolves the passive film outright, and even trace fluoride in an otherwise benign stream is dangerous. Dry chlorine can cause ignition.
Hydrogen embrittlement from cathodic protection or from acid pickling, forming brittle hydrides.
Ignition risk. Fine chips burn, and in high-pressure oxygen or in a compressor rub event titanium can sustain combustion — the reason titanium is excluded from the hot sections of engines and requires careful swarf handling in the shop.
Fabrication notes
Machinability is poor, roughly 20–25% of B1112. Thermal conductivity is very low, so heat stays in the cutting zone and the chip; low speeds, high feeds, sharp tools, rigid setups and copious coolant are mandatory. Never let the tool dwell — work hardening and galling follow immediately, and chip fires are a genuine shop hazard.
Welding requires complete inert shielding, including the root and the cooling weld metal, because titanium absorbs oxygen, nitrogen and hydrogen readily above 500 °C and becomes brittle. Trailing shields and purge chambers are standard. Weld colour is the field inspection: silver is acceptable, straw and light blue are marginal, and dark blue, grey or white powder indicate contamination and require removal.
Forming is done warm for Ti-6Al-4V because room-temperature ductility is limited; springback is high, and hot forming or creep forming is common.
Specifications and standards
ASTM B265 (sheet/plate), B348 (bar), B338 (tube); ASTM F136 and ISO 5832-3 for surgical implant Ti-6Al-4V ELI; AMS 4911 and 4928 for aerospace sheet and bar; AWS D17.1 for aerospace fusion welding; ASME BPVC Section II for allowables.
References
ASM Specialty Handbook, Titanium and Titanium Alloys; Donachie, Titanium: A Technical Guide; Timet and VSMPO technical data sheets.
Property interpretation
Stiffness vs strength
Young’s modulus controls elastic deformation. Yield or fracture strength controls how far the material can be stressed. These are separate material characteristics.
Thermal response
Thermal conductivity controls temperature gradients, specific heat contributes to thermal inertia, and expansion controls thermally induced strain when movement is restrained.
Temperature transition
The final property card is deliberately labeled “melting / transition.” Metals often have a solidus–liquidus range; amorphous polymers and glass use softening or glass-transition concepts; concrete and wood decompose instead of exhibiting one clean melt point.
Technical sources
Source hierarchy favors manufacturers, industry associations, standards bodies and government engineering references. Strength data must still be reconciled with the exact procurement specification.