Titanium Grade 6
ASTM Grade 6 · UNS R54520 · EN 3.7115 · GB TA7
Grade 6 (Ti-5Al-2.5Sn, 3.7115, TA7) is an early alpha titanium alloy with good weldability (score 75) and stable strength from cryogenic temperatures up to about 450 °C, the highest service ceiling in this group.
Values for the O condition
Grade 6 tempers and conditions
Grade 6 is supplied in 3 conditions, soft to hard. O is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed, extra low interstitial | Pick for cryogenic tankage and structures down to liquid-hydrogen temperature, where the low oxygen/nitrogen content preserves toughness at some loss of room-temperature strength. | 740 | 800 | 18 | 290 HB | — |
ODefault Annealed | Standard stocked condition for sheet, plate, bar and forgings used up to ~480 °C; annealed 700–845 °C and air cooled. | 810 | 860 | 16 | 33 HRC | — |
Stress relieved | Used for cold-drawn tubing and cold-rolled strip where slightly higher strength and straightness are wanted; retained cold work raises yield but cuts ductility. | 880 | 930 | 12 | 35 HRC | 1.1 % IACS |
What is Grade 6?
Grade 6 (Ti-5Al-2.5Sn, 3.7115, TA7) is an early alpha titanium alloy with good weldability (score 75) and stable strength from cryogenic temperatures up to about 450 °C, the highest service ceiling in this group. Annealed properties are 810 MPa yield, 860 MPa tensile and 16% elongation at about 310 HB (33 HRC), and it is used mainly for aerospace forgings and cryogenic tankage, with an ELI variant on file for low-temperature toughness. As an alpha alloy it is not strengthened by heat treatment, formability is limited (score 30) so hot forming is standard, and machinability is 22. Ti-6Al-4V (Grade 5) is the usual alternative where cryogenic weld ductility is not the driver. Grade 6 has a density of 4.48 g/cm³ (0.162 lb/in³), lighter than 71% of titanium grades. It melts at 1,590°C (2,894 °F). Grade 6 has a yield strength of 810 MPa (117 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 59% of titanium grades. Elongation at break is 16% and the elastic modulus is 110 GPa (16 Msi).
What is Grade 6 used for?
- Cryogenic LH2 tanks
- Aerospace forgings and structural fittings
- Rocket engine and turbopump hardware
- Welded pressure vessel shells
- Compressor casings and rings
- Airframe high-temperature brackets
Advantages
- High service temperature — 450°C (842 °F), better than 87% of titanium grades
Grade 6 properties
Typical room-temperature values for Grade 6-O; bars are the position among titanium grades.
Physical3
Grade 6 has a density of 4.48 g/cm³ (0.162 lb/in³), lighter than 71% of titanium grades. It melts at 1,590°C (2,894 °F).
Mechanical16
Grade 6 has a yield strength of 810 MPa (117 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 59% of titanium grades. Elongation at break is 16% and the elastic modulus is 110 GPa (16 Msi).
Thermal6
Grade 6 is rated for continuous service to 450°C (842 °F). It conducts heat at 7.8 W/m·K (4.51 BTU/hr·ft·°F), worse than 53% of titanium grades. Thermal expansion is 9.5 µm/m·K (5.28 µin/in·°F).
Electrical3
Grade 6 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 Grade 6 takes about 650 MJ of energy and emits 44 kg of CO₂ — less than 75% of titanium grades. Typical recycled content is 25%.
Manufacturability7
Grade 6's machinability is poor (22/100, worse than 55% of titanium grades); weldability very good (75/100); formability poor (30/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the titanium family
Yield strength against density for every titanium grade FabDigit runs. Grade 6 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Grade 6
Is Grade 6 easy to machine?
Machine like other alpha/alpha-beta titanium: rigid setups, sharp uncoated-carbide or coated carbide tools, low surface speed (~20–40 m/min), heavy feed and flood coolant to avoid work hardening, galling and fire risk from fine chips.
Can Grade 6 be welded?
One of the more weldable titanium alloys — GTAW, plasma, EB and laser welds with matching or Ti-5Al-2.5Sn ELI filler retain good ductility; full inert-gas or vacuum shielding of the weld and heat-affected zone is mandatory, followed by a 540–650 °C stress relief.
Can Grade 6 be formed, bent or molded?
Limited cold formability (large bend radii, high springback); hot forming or creep forming at 480–760 °C is standard, with post-form anneal and pickling to remove alpha case.
Manufacturability
The process limits FabDigit's quote engine applies to Grade 6. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Fair22 / 100 |
|---|---|
| ISO material group | S.3 |
| Cutting speed (rough / finish) | 60 / 75 m/min |
| Minimum wall | 1 mm |
| Minimum internal radius | 1.5 mm |
| Drill depth limit | 4× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Fair30 / 100 |
|---|---|
| Weldability | Good75 / 100 |
| Bendable | Yes |
Grade 6 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 |
|---|---|---|
| Al | 4 – 6 | 5 |
| Sn | 2 – 3 | 2.5 |
| FeELI: 0.25 max | ≤ 0.5 | 0.25 |
| OELI: 0.12 max | ≤ 0.2 | 0.15 |
| CELI: 0.05 max | ≤ 0.08 | 0.03 |
| NELI: 0.035 max | ≤ 0.05 | 0.02 |
| H0.015 max sheet/strip; ELI 0.0125 max | ≤ 0.02 | 0.01 |
| Residuals (each)0.40 max total | ≤ 0.1 | |
| Ti | balance |
What surface finishes work on Grade 6?
Descale by molten-salt/alkaline plus HNO₃-HF pickling to remove alpha case; anodize (AMS 2488) or dry-film lubricate anti-galling surfaces; can be shot peened for fatigue and takes a good mechanical polish.
Surface treatments FabDigit runs on titanium parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Conversion Coating
Organic Coating
CVD Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Titanium Grade 6 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- R54520
- EN / DIN / Werkstoff-Nr.
- 3.7115
- GB (China)
- TA7
How much does Grade 6 cost?
Grade 6 is a specialty-cost titanium ($$$$$), pricier than about 99% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Grade 6 — frequently asked
What is Grade 6 used for?
Grade 6 is typically used for cryogenic LH2 tanks, aerospace forgings and structural fittings, rocket engine and turbopump hardware, welded pressure vessel shells, compressor casings and rings and airframe high-temperature brackets. In short: weldable aerospace titanium.
What is the yield strength of Grade 6?
Grade 6 has a typical yield strength of 810 MPa (117 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 59% of titanium grades. Strength varies by condition: see the 3 listed tempers.
Is Grade 6 easy to machine?
Not especially — machinability is rated poor (22/100, worse than 55% of titanium grades). Machine like other alpha/alpha-beta titanium: rigid setups, sharp uncoated-carbide or coated carbide tools, low surface speed (~20–40 m/min), heavy feed and flood coolant to avoid work hardening, galling and fire risk from fine chips.
Can Grade 6 be welded?
Yes — weldability is rated very good (75/100). One of the more weldable titanium alloys — GTAW, plasma, EB and laser welds with matching or Ti-5Al-2.5Sn ELI filler retain good ductility; full inert-gas or vacuum shielding of the weld and heat-affected zone is mandatory, followed by a 540–650 °C stress relief.
What surface finishes work on Grade 6?
Descale by molten-salt/alkaline plus HNO₃-HF pickling to remove alpha case; anodize (AMS 2488) or dry-film lubricate anti-galling surfaces; can be shot peened for fatigue and takes a good mechanical polish.
Can Grade 6 be formed, bent or molded?
Limited cold formability (large bend radii, high springback); hot forming or creep forming at 480–760 °C is standard, with post-form anneal and pickling to remove alpha case.
What is the maximum service temperature of Grade 6?
Grade 6 is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Grade 6-O and Grade 6-ELI?
O is the default condition — standard stocked condition for sheet, plate, bar and forgings used up to ~480 °C; annealed 700–845 °C and air cooled. ELI: pick for cryogenic tankage and structures down to liquid-hydrogen temperature, where the low oxygen/nitrogen content preserves toughness at some loss of room-temperature strength. Yield strength is 810 MPa in O versus 740 MPa in ELI.
How much does Grade 6 cost?
Grade 6 is a specialty-cost titanium ($$$$$), pricier than about 99% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in Grade 6?
Yes — Grade 6 is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM B265 — Titanium and Titanium Alloy Strip, Sheet and Plate (Grade 6) — ASTM International (2020)
- ASTM B348 — Titanium and Titanium Alloy Bars and Billets (Grade 6) — ASTM International (2021)
- AMS 4910 / AMS 4909 / AMS 4926 / AMS 4924 — Ti-5Al-2.5Sn sheet and bar, annealed and ELI — SAE International (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Materials Properties Handbook: Titanium Alloys — ASM International (1994)
- MMPDS — Metallic Materials Properties Development and Standardization (Ti-5Al-2.5Sn) — Battelle/FAA (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.