Titanium Ti-17-STA (Solution treated and aged)
Heat-treated state · default condition
UNS R58650 · GB TC17
Standard high-strength condition for fan/compressor disks and thick forgings needing strength plus good LCF life.
Values for the STA condition
Other Ti-17 tempers and conditions
Ti-17 is listed in 5 conditions; see the grade overview at Ti-17.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Supplied for further hot working, machining of near-net shapes or straightening before the customer performs the ageing cycle. | 880 | 950 | 15 | 31 HRC | 1 % IACS |
As-forged / mill-annealed billet and bar | Raw billet, bar and forging stock condition sold for onward forging; not a design-strength condition. | 930 | 1,020 | 12 | 33 HRC | 1 % IACS |
Overaged | Used where dimensional/thermal stability and toughness matter more than peak strength, e.g. large stabilised disk forgings. | 950 | 1,030 | 12 | 34 HRC | 1 % IACS |
Beta solution treated (above beta transus ~890-900 °C) and aged | Choose when maximum fracture toughness and crack-growth resistance in very thick sections outweigh a modest loss of ductility and fatigue strength. | 1,020 | 1,100 | 7 | 36 HRC | 1 % IACS |
STADefaultThis page Solution treated and aged | Standard high-strength condition for fan/compressor disks and thick forgings needing strength plus good LCF life. | 1,075 | 1,150 | 10 | 37 HRC | — |
What is Ti-17-STA?
Ti-17-STA is Ti-17 heat treated to STA — standard high-strength condition for fan/compressor disks and thick forgings needing strength plus good LCF life. Ti-17-STA has a yield strength of 1,075 MPa (156 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 98% of titanium grades. Elongation at break is 10% and the elastic modulus is 112 GPa (16.2 Msi). Ti-17-STA has a density of 4.65 g/cm³ (0.168 lb/in³), heavier than 90% of titanium grades. It melts at 1,600°C (2,912 °F).
Advantages
- High strength — 1,075 MPa (156 ksi), better than 98% of titanium grades
Limitations
- Difficult to weld — 30/100, worse than 98% of titanium grades
- Limited ductility — 10%, worse than 93% of titanium grades
- Limited formability — 15/100, worse than 93% of titanium grades
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 90% of titanium grades
Ti-17-STA properties
Typical room-temperature values for Ti-17-STA; 11 are specific to this condition. Other listed values are Ti-17 reference data and may not represent this condition. Bars are the position among titanium grades.
Physical3
Ti-17-STA has a density of 4.65 g/cm³ (0.168 lb/in³), heavier than 90% of titanium grades. It melts at 1,600°C (2,912 °F).
Mechanical15
Ti-17-STA has a yield strength of 1,075 MPa (156 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 98% of titanium grades. Elongation at break is 10% and the elastic modulus is 112 GPa (16.2 Msi).
Thermal6
Ti-17-STA is rated for continuous service to 350°C (662 °F). It conducts heat at 7 W/m·K (4.04 BTU/hr·ft·°F), worse than 76% of titanium grades. Thermal expansion is 9.4 µm/m·K (5.22 µin/in·°F).
Electrical2
Ti-17-STA has an electrical resistivity of 1.7×10⁻⁶ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), worse than 93% of titanium grades.
Sustainability4
Producing a kilogram of Ti-17-STA takes about 680 MJ of energy and emits 42 kg of CO₂ — more than 51% of titanium grades. Typical recycled content is 20%.
Manufacturability7
Ti-17-STA's machinability is poor (16/100, worse than 93% of titanium grades); weldability poor (30/100); formability poor (15/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Ti-17-STA
Is Ti-17 easy to machine?
Machine like a hard beta-rich titanium: rigid setup, sharp uncoated-carbide or coated inserts, ~15-30 m/min in the aged condition, heavy flood coolant, positive rake and no dwelling to avoid work hardening and edge notching.
Can Ti-17 be welded?
GTAW/EBW is metallurgically possible with full inert or vacuum shielding, but the aged HAZ loses ductility, so post-weld solution+age is required and welding is normally excluded from critical rotating hardware.
Can Ti-17 be formed, bent or molded?
Essentially a hot-work alloy — forge/ring-roll just below or above the beta transus (~850-925 °C) with controlled cooling; cold forming is impractical, so bends and rings are made hot or by machining.
What surface finishes work on Ti-17?
Shot peen or low-stress grind highly loaded surfaces; anodic/AMS 2488 conversion coatings, ion plating or dry-film lube prevent galling, and pickling must avoid hydrogen pickup.
Ti-17 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Alalpha stabilizer | 4.5 – 5.5 | 5 |
| Sn | 1.6 – 2.4 | 2 |
| Zr | 1.6 – 2.4 | 2 |
| Mobeta stabilizer, deep hardenability | 3.5 – 4.5 | 4 |
| Crbeta stabilizer | 3.5 – 4.5 | 4 |
| Fe | ≤ 0.3 | — |
| Ocontrolled range | 0.08 – 0.13 | 0.11 |
| C | ≤ 0.05 | — |
| N | ≤ 0.05 | — |
| H | ≤ 0.01 | — |
| Simax (some specs) | ≤ 0.15 | — |
| Ti | balance | — |
Ti-17-STA — frequently asked
What is Ti-17-STA used for?
Ti-17-STA is typically used for jet engine fan disks, compressor disks and high-strength rotating parts. In short: deep-hardening disk alloy; high fracture toughness; hot-work only, no cold forming.
What is the yield strength of Ti-17-STA?
Ti-17-STA has a typical yield strength of 1,075 MPa (156 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 98% of titanium grades. Strength varies by condition: see the 5 listed tempers.
Is Ti-17-STA easy to machine?
Not especially — machinability is rated poor (16/100, worse than 93% of titanium grades). Machine like a hard beta-rich titanium: rigid setup, sharp uncoated-carbide or coated inserts, ~15-30 m/min in the aged condition, heavy flood coolant, positive rake and no dwelling to avoid work hardening and edge notching.
Can Ti-17-STA be welded?
Not readily — weldability is rated poor (30/100). GTAW/EBW is metallurgically possible with full inert or vacuum shielding, but the aged HAZ loses ductility, so post-weld solution+age is required and welding is normally excluded from critical rotating hardware.
What surface finishes work on Ti-17-STA?
Shot peen or low-stress grind highly loaded surfaces; anodic/AMS 2488 conversion coatings, ion plating or dry-film lube prevent galling, and pickling must avoid hydrogen pickup.
Can Ti-17-STA be formed, bent or molded?
Essentially a hot-work alloy — forge/ring-roll just below or above the beta transus (~850-925 °C) with controlled cooling; cold forming is impractical, so bends and rings are made hot or by machining.
What is the maximum service temperature of Ti-17-STA?
Ti-17-STA is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Ti-17-STA and Ti-17-ST?
STA is the default condition — standard high-strength condition for fan/compressor disks and thick forgings needing strength plus good LCF life. ST: supplied for further hot working, machining of near-net shapes or straightening before the customer performs the ageing cycle. Yield strength is 1,075 MPa in STA versus 880 MPa in ST.
Sources
- AMS 4995 — Titanium Alloy Forgings Ti-5Al-2Sn-2Zr-4Mo-4Cr, Solution and Precipitation Heat Treated — SAE International (2019)
- AMS 4970 — Titanium Alloy Bars, Forgings and Rings Ti-5Al-2Sn-2Zr-4Mo-4Cr — SAE International (2018)
- Materials Properties Handbook: Titanium Alloys — ASM International (1994)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- GB/T 2965 / TC17 (2007)
- Ti-17 (TC17) forging billet datasheets (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.