Titanium BT20-STA (Solution treated and aged)
Heat-treated state
GB BT20
Use solution treating plus ageing only on small-section parts where a 5-10% strength gain is needed; near-alpha strengthening potential is limited and elongation drops to 8%.
Values for the STA condition
Other BT20 tempers and conditions
BT20 is listed in 5 conditions; see the grade overview at BT20.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As hot-worked / hot-rolled | Pick the as hot-worked or hot-rolled state as the economical supply form for thick plate, bar and forging stock, then anneal or stress relieve before use; machinability is lowest at 16. | 860 | 960 | 10 | 33 HRC | 1.1 % IACS |
MDefault Thermomechanically controlled processed | Take the common annealed (750-800 °C) sheet and bar supply condition for a balance of 880 MPa yield and 12% elongation that can be welded and machined directly. | 880 | 990 | 12 | 32 HRC | — |
Duplex (double) annealed | Specify duplex (double) annealing for load-carrying hot-section parts to 500 °C that need long-term thermal stability and creep resistance, with service capability to 520 °C. | 900 | 980 | 12 | 33 HRC | 1.1 % IACS |
Stress relieved | Apply 600-650 °C stress relief to welded or hot-formed parts to remove residual stress with almost no change in strength level (900 MPa yield, 1000 MPa tensile). | 900 | 1,000 | 11 | 33 HRC | 1.1 % IACS |
STAThis page Solution treated and aged | Use solution treating plus ageing only on small-section parts where a 5-10% strength gain is needed; near-alpha strengthening potential is limited and elongation drops to 8%. | 990 | 1,080 | 8 | 36 HRC | — |
What is BT20-STA?
BT20-STA is BT20 heat treated to STA — use solution treating plus ageing only on small-section parts where a 5-10% strength gain is needed; near-alpha strengthening potential is limited and elongation drops to 8%. BT20-STA has a yield strength of 990 MPa (144 ksi) and a tensile strength of 1,080 MPa (157 ksi) — stronger than 92% of titanium grades. Elongation at break is 8% and the elastic modulus is 118 GPa (17.1 Msi). BT20-STA has a density of 4.46 g/cm³ (0.161 lb/in³), lighter than 78% of titanium grades. It melts at 1,590°C (2,894 °F). M is the default condition FabDigit quotes; STA is available on request or by drawing note.
Advantages
- Stiff — 118 GPa (17.1 Msi), better than 96% of titanium grades
- High strength — 990 MPa (144 ksi), better than 92% of titanium grades
- High service temperature — 480°C (896 °F), better than 90% of titanium grades
Limitations
- Limited ductility — 8%, worse than 99% of titanium grades
- Hard to polish — 60/100, worse than 97% of titanium grades
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 90% of titanium grades
BT20-STA properties
Typical room-temperature values for BT20-STA; 10 are specific to this condition. Other listed values are BT20 reference data and may not represent this condition. Bars are the position among titanium grades.
Physical3
BT20-STA has a density of 4.46 g/cm³ (0.161 lb/in³), lighter than 78% of titanium grades. It melts at 1,590°C (2,894 °F).
Mechanical16
BT20-STA has a yield strength of 990 MPa (144 ksi) and a tensile strength of 1,080 MPa (157 ksi) — stronger than 92% of titanium grades. Elongation at break is 8% and the elastic modulus is 118 GPa (17.1 Msi).
Thermal6
BT20-STA is rated for continuous service to 480°C (896 °F). It conducts heat at 7.5 W/m·K (4.33 BTU/hr·ft·°F), worse than 65% of titanium grades. Thermal expansion is 8.6 µm/m·K (4.78 µin/in·°F).
Electrical3
BT20-STA conducts electricity at 1.1 % IACS, worse than 67% of titanium grades.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), worse than 93% of titanium grades.
Sustainability4
Producing a kilogram of BT20-STA takes about 680 MJ of energy and emits 45 kg of CO₂ — more than 51% of titanium grades. Typical recycled content is 25%.
Manufacturability7
BT20-STA's machinability is poor (15/100, worse than 97% of titanium grades); weldability very good (72/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with BT20-STA
Is BT20 easy to machine?
Use low speed, high feed, rigid clamping and high-pressure coolant with carbide or diamond-coated tooling. Keep depth of cut constant to avoid work hardening and built-up edge.
Can BT20 be welded?
TIG, plasma, electron-beam and laser welding are all usable with continuous inert-gas or vacuum shielding, followed by stress relief at 600–650 °C. Weld strength is close to the parent metal, with slightly reduced ductility.
Can BT20 be formed, bent or molded?
Room-temperature formability is poor; bend and draw at 650–800 °C or use superplastic forming. Forging is carried out at roughly 930–990 °C in the alpha+beta field.
What surface finishes work on BT20?
Pickle in HNO₃/HF to remove scale and alpha case. Colour anodising, micro-arc oxidation or shot peening can follow; avoid chlorine-bearing solvent residues that can cause stress corrosion.
BT20 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, high aluminum equivalent | 5.5 – 7 | 6.4 |
| Zr | 1.5 – 2.5 | 2 |
| Mo | 0.5 – 2 | 1.5 |
| V | 0.8 – 2.5 | 1.5 |
| Feimpurity limit | ≤ 0.25 | — |
| Siimpurity limit | ≤ 0.15 | — |
| Oimpurity limit | ≤ 0.15 | — |
| Cimpurity limit | ≤ 0.1 | — |
| Nimpurity limit | ≤ 0.05 | — |
| Himpurity limit | ≤ 0.02 | — |
| Ti | balance | — |
BT20-STA — frequently asked
What is BT20-STA used for?
BT20-STA is typically used for airframe structural parts, welded panels and bulkheads, hot-formed and superplastically formed skins, forged frames and fittings, engine mounting brackets and welded hot-air ducting. In short: strongest weldable near-alpha; 500 °C service capability; hot forming required.
What is the yield strength of BT20-STA?
BT20-STA has a typical yield strength of 990 MPa (144 ksi) and a tensile strength of 1,080 MPa (157 ksi) — stronger than 92% of titanium grades. Strength varies by condition: see the 5 listed tempers.
Is BT20-STA easy to machine?
Not especially — machinability is rated poor (15/100, worse than 97% of titanium grades). Use low speed, high feed, rigid clamping and high-pressure coolant with carbide or diamond-coated tooling. Keep depth of cut constant to avoid work hardening and built-up edge.
Can BT20-STA be welded?
Yes — weldability is rated very good (72/100). TIG, plasma, electron-beam and laser welding are all usable with continuous inert-gas or vacuum shielding, followed by stress relief at 600–650 °C. Weld strength is close to the parent metal, with slightly reduced ductility.
What surface finishes work on BT20-STA?
Pickle in HNO₃/HF to remove scale and alpha case. Colour anodising, micro-arc oxidation or shot peening can follow; avoid chlorine-bearing solvent residues that can cause stress corrosion.
Can BT20-STA be formed, bent or molded?
Room-temperature formability is poor; bend and draw at 650–800 °C or use superplastic forming. Forging is carried out at roughly 930–990 °C in the alpha+beta field.
What is the maximum service temperature of BT20-STA?
BT20-STA is rated for continuous use to about 480°C (896 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between BT20-M and BT20-STA?
M is the default condition — take the common annealed (750-800 °C) sheet and bar supply condition for a balance of 880 MPa yield and 12% elongation that can be welded and machined directly. STA: use solution treating plus ageing only on small-section parts where a 5-10% strength gain is needed; near-alpha strengthening potential is limited and elongation drops to 8%. Yield strength is 880 MPa in M versus 990 MPa in STA.
Sources
- GOST 19807-91 Титан и сплавы титановые деформируемые. Марки — Gosstandart (1991)
- ASM Handbook Vol. 2 — Properties of Nonferrous Alloys (Titanium) — ASM International (1990)
- Марочник стали и сплавов — сплав ВТ20 — Mashinostroenie (2003)
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.