Key facts
| Property | Value | Source |
|---|---|---|
| Against steel and aluminum | 30 % stronger than steel and nearly 50 % lighter; 60 % heavier than aluminum and twice as strong | FAA-H-8083-31, p. 4-85 (the handbook's general statement, not a design value) |
| Against pure titanium | Approximately 3 times stronger | FAA-H-8083-31, p. 4-85 |
| Service temperature | Moderate strength up to 600 °F (315 °C) | FAA-H-8083-31, p. 4-85 |
| Stress relief after cold forming (annealed 6Al-4V) | Above 1,250 °F and below 1,450 °F, held more than 30 minutes and less than 10 hours | FAA-H-8083-31, p. 4-85 |
| Largest hole drilled in one step | 0.1563 in | FAA-H-8083-31, p. 4-86 |
| Heat tint colours | Blue at 700–800 °F, purple at 800–950 °F, gray or black at 1,000 °F or higher | AC 43.13-1B CHG 1, par. 6-181a |
The 30 % and 60 % comparisons are the handbook's own wording. Do not use them in a calculation; use the allowables for the exact condition.
Design allowables — Ti-6Al-4V annealed sheet
0.1875 in and under. MIL-HDBK-5J Table 5.4.1.0(b). A and B bases in ksi unless a unit is shown.
| Property | A basis | B basis | Unit |
|---|---|---|---|
| Ftu, L | 134 | 139 | ksi |
| Ftu, LT | 134 | 139 | ksi |
| Fty, L | 126 | 131 | ksi |
| Fty, LT | 126 | 131 | ksi |
| Fcy, L | 133 | 138 | ksi |
| Fcy, LT | 135 | 141 | ksi |
| Fsu | 87 | 90 | ksi |
| Fbru, e/D = 1.5 | 213 | 221 | ksi |
| Fbru, e/D = 2.0 | 272 | 283 | ksi |
| Property | A basis | B basis | Unit |
|---|---|---|---|
| Fbry, e/D = 1.5 | 171 | 178 | ksi |
| Fbry, e/D = 2.0 | 208 | 217 | ksi |
| Elongation, L (S-basis) | 8 | — | % |
| Elongation, LT (S-basis) | 8 | — | % |
| E | 16.0 | 16.0 | 10³ ksi |
| Ec | 16.4 | 16.4 | 10³ ksi |
| G | 6.2 | 6.2 | 10³ ksi |
| Density | 0.160 | 0.160 | lb/in³ |
Form: sheet; condition: annealed; specification: AMS 4911 and AMS-T-9046 Comp. AB-1; thickness 0.1875 in and under. Bearing values are dry-pin values (MIL-HDBK-5J Section 1.4.7.1). The handbook footnotes the elongation: 8% for 0.025 to 0.062 in and 10% for 0.063 in and above, printed in the A column with the B cell blank. E, Ec, G and density are printed once across all columns. Source: MIL-HDBK-5J (31 Jan 2003), Table 5.4.1.0(b), p. 5-53. MIL-HDBK-5J (2003) is superseded by MMPDS; check current MMPDS before design use. Density 0.160 lb/in³ is about 4.43 g/cm³ (converted), from the same MIL-HDBK-5J table.
Where it is used
The AMT Handbook says titanium alloys are used chiefly for parts that need good corrosion resistance, moderate strength up to 600 °F and light weight. Ti-6Al-4V is used in aircraft turbine engine components and in aircraft structural components, and is the most widely used titanium alloy (p. 4-85).
For installing titanium parts the handbook recommends Monel rivets or standard close-tolerance steel fasteners (p. 4-85).
Forming, drilling and isolation
Forming. Ti-6Al-4V is hard to form. Use a minimum radius chart, because too small a radius puts excess stress in the bend. A powerful press brake is required; hand box and pan brakes cannot form it (p. 4-85).
Drilling. Use carbide or 8 percent cobalt tools and a positive power feed where possible. Never let a blunt bit rub without cutting: the surface work hardens and is very difficult to restart. Holes of 0.1875 in and larger are stepped up from 0.1563 in, in increments of 0.0313 or 0.0625 in (p. 4-86).
Isolation. Titanium must be isolated from magnesium, aluminum and alloy steel, because the other metal suffers galvanic corrosion or oxidation on contact (p. 4-85).
Corrosion, hydrogen and tools
Titanium is highly corrosion-resistant because an oxide film forms on contact with air. If corrosion does develop it usually shows as pitting, and it is difficult to detect (AC par. 6-181).
Surfaces are susceptible to hydrogen embrittlement. Chlorinated hydrocarbon solvents and chemical corrosion removers are prohibited on titanium (AC par. 6-181c).
Dry abrasive blasting of titanium creates sparking; make sure there are no flammable vapors. Small particles of titanium burn very easily (AC par. 6-181b; AMT Handbook p. 4-85).
Questions people actually ask
Why do I have to keep titanium away from aluminum?
The AMT Handbook says galvanic corrosion or oxidation of the other metal occurs on contact. Isolate it, and use the fasteners the SRM calls for.
Can I hand-drill a 1/4 in hole in titanium?
Not in one step. The handbook limits a single-step hole to 0.1563 in, and says larger holes are stepped up in 0.0313 or 0.0625 in increments.
Limits — when NOT to use this
- Not a source of design allowables. Strength depends on the condition and form. Use MMPDS with the basis; the SRM governs a repair.
- No bend radii on this page. AC Table 4-6 covers aluminum only. The minimum radius chart for the actual alloy and condition comes from the manufacturer or SRM.
- Not a substitute for steel or aluminum. Substitution changes stiffness, weight and galvanic pairs. It is approved-data territory.
- Welding is outside this page. Titanium welding is its own procedure; see “TIG Welding Titanium” in the AMT Handbook, Chapter 5.
Sources
- FAA-H-8083-31, AMT Handbook — Airframe, Volume 1, Chapter 4 — Working Titanium, pp. 4-85 to 4-86 — description, alloy comparison, forming with stress relief, drilling and isolation.
- FAA AC 43.13-1B CHG 1, Chapter 6 — par. 6-181 — oxide colours, pitting, hydrogen embrittlement and prohibited solvents.
- MIL-HDBK-5J, Metallic Materials and Elements for Aerospace Vehicle Structures — density as used on our kit weight page; the home of the design allowables (Chapter 5, titanium). Cancelled; replaced by MMPDS.
- MIL-HDBK-5J (31 Jan 2003), Table 5.4.1.0(b), p. 5-53 — Ti-6Al-4V annealed sheet, 0.1875 in and under: Ftu, Fty, Fcy, Fsu, Fbru, Fbry, elongation, E, Ec, G and density.
- MMPDS (formerly MIL-HDBK-5) — the current home of design allowables with A, B and S basis. Cancelled MIL-HDBK-5J was superseded by it. A repair substantiation cites MMPDS or the SRM, not a website.