Titanium BT20-SR (Stress relieved)
Heat-treated state
GB BT20
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).
Values for the SR 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 |
SRThis page 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 |
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-SR?
BT20-SR is BT20 heat treated to SR — 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). BT20-SR has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 82% of titanium grades. Elongation at break is 11% and the elastic modulus is 119 GPa (17.3 Msi). BT20-SR 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; SR is available on request or by drawing note.
Advantages
- Stiff — 119 GPa (17.3 Msi), better than 97% of titanium grades
- High service temperature — 500°C (932 °F), better than 94% of titanium grades
- High strength — 900 MPa (131 ksi), better than 82% of titanium grades
Limitations
- Hard to polish — 60/100, worse than 97% of titanium grades
- Limited ductility — 11%, worse than 87% of titanium grades
BT20-SR properties
Typical room-temperature values for BT20-SR; 22 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-SR 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-SR has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 82% of titanium grades. Elongation at break is 11% and the elastic modulus is 119 GPa (17.3 Msi).
Thermal6
BT20-SR is rated for continuous service to 500°C (932 °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-SR 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-SR 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-SR's machinability is poor (17/100, worse than 89% of titanium grades); weldability very good (74/100); formability poor (28/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with BT20-SR
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-SR — frequently asked
What is BT20-SR used for?
BT20-SR 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-SR?
BT20-SR has a typical yield strength of 900 MPa (131 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 82% of titanium grades. Strength varies by condition: see the 5 listed tempers.
Is BT20-SR easy to machine?
Not especially — machinability is rated poor (17/100, worse than 89% 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-SR be welded?
Yes — weldability is rated very good (74/100). 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-SR?
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-SR 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-SR?
BT20-SR is rated for continuous use to about 500°C (932 °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.