Alloy Temper Designations

The temper suffix carries as much information as the alloy number — 6061-O and 6061-T6 are the same metal with roughly a 4× difference in yield strength.

Aluminium (ANSI H35.1)

Temper	Meaning	Notes
F	As fabricated	No control over thermal or work hardening
O	Annealed	Softest, most formable condition
H1x	Strain hardened only	H12/H14/H16/H18 = quarter/half/three-quarter/full hard
H2x	Strain hardened, partially annealed	Better ductility than H1x at the same strength
H3x	Strain hardened, stabilised	For alloys that age-soften (Mg-bearing 5xxx)
T3	Solution treated, cold worked, naturally aged	e.g. 2024-T3 sheet
T4	Solution treated, naturally aged	Good formability, ages at room temperature
T6	Solution treated, artificially aged	Peak strength — 6061-T6, 7075-T6
T7x	Solution treated, overaged	T73/T76 trade strength for stress-corrosion resistance
T8x	Solution treated, cold worked, artificially aged	e.g. 2024-T851 plate

Titanium conditions

Condition	Designation	Notes
Annealed	Ti-6Al-4V annealed	Standard condition — best ductility and weldability
STA	Solution treated & aged	Higher strength, lower ductility and toughness
ELI	Extra low interstitial	Lower O/N/C — better fracture toughness, cryogenic use
Mill annealed	Common plate/sheet supply	Balanced properties, most available
Beta annealed	Above the beta transus	Improved damage tolerance, lower ductility
CP Gr 1–4	Commercially pure	Strength rises Gr1 → Gr4 with oxygen content

Look up properties in the material reference or rank candidates with the Material Selector. Design allowables for flight hardware come from MMPDS, not from typical values.

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