Ti-5553 Titanium
A very high-strength near-beta titanium alloy
Typical values for the temper in the title
Ti-5553 contains 5% aluminum, 5% molybdenum, 5% vanadium and 3% chromium. It was developed to reach very high strength (about 1200 MPa tensile and more) even in thick parts, where Ti-10-2-3 struggles to maintain properties.
It is used for landing gear and heavy structural parts on newer aircraft, where it replaces steel while keeping weight low and corrosion resistance high.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 1200 MPa | |
| Yield strength Rp0.2 | 1100 MPa | |
| Elongation A | 8% | |
| Hardness | 360 HB | |
| Modulus of elasticity E | 114 GPa | |
| Density ρ | 4.65 g/cm³ | |
| Machinability | 25% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Al aluminum | about 5 (nominal) | strengthening |
| Mo molybdenum | about 5 (nominal) | beta stabilizer |
| V vanadium | about 5 (nominal) | beta stabilizer |
| Cr chromium | about 3 (nominal) | beta stabilizer |
| Ti titanium | balance |
Nominal composition, as given in the alloy name. Exact ranges are defined in AMS and producer specifications.
Conditions and heat treatment
Near-beta alloys are hardened by solution treatment and aging.
| Condition | Properties | When to choose it |
|---|---|---|
| Solution treated and aged | about 1200 MPa tensile and more (database value) | landing gear and thick structural parts |
Applications
- Landing gear
- Thick aerospace structural parts
- Wing attachments
- Heavy forgings
- High-strength fasteners
Fabrication
Machining
Titanium conducts heat poorly, so heat stays at the tool edge. Use low cutting speed, adequate feed (do not "rub"), sharp tools and plenty of coolant. Fine chips can ignite.
Welding
Welds well by TIG, but only with full inert-gas shielding, including a trailing shield and backing gas. Oxygen and nitrogen from the air embrittle the weld. Weld color (silver, not blue or grey) indicates shielding quality.
Threads and contact
Titanium tends to gall in sliding contact. Use anti-seize compound on threads.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| Ti-10-2-3 | 1250 / 1100 MPa | Difficult | an older near-beta alloy · material page |
| Ti-6Al-4V (Grade 5) | 950–1100 / 880 MPa | Good — ERTi-5 | weaker, more common · material page |
| AerMet 100 | 1965 / 1725 MPa | Good — ER250 filler | a high-strength steel, much heavier · material page |
Common mistakes
Looking for its ASTM Grade
It has no ASTM grade. It is defined in producer and aircraft-builder specifications. Some sources wrongly assign it Grade 21, a different alloy.
Machining with Ti-6Al-4V parameters
At this strength machining is even harder. Suitable parameters are needed.
Departing from the heat treatment
Properties are very process-sensitive.
Equivalents, standards and supply
| Standards | Producer and aircraft-builder specifications |
|---|---|
| Forms | plate · rod · forging |
| Producers | TIMET · ATI · VSMPO |
Learn more
Values are typical and for comparison only. For design, rely on the standard and the mill certificate. Sources: ASTM B265 (sheet and plate), ASTM F136, AMS specifications, producer data sheets, and the METAL HUB materials database.
Updated: October 31, 2026