Ti Grade 5 / (Ti6Al4V) / UNS R56400 / AMS 4928 / AMS 4911
DEFENCE METAL
Ti Grade 5 (Ti-6Al-4V)
UNS R56400 · W.Nr. 3.7165 (3.7164 in aerospace quality) · ASTM Grade 5 · Ti-6Al-4V · ALPHA-BETA (two-phase) titanium alloy. ASTM B265 / B348 Grade 5 limits: Al 5.5-6.75% · V 3.5-4.5% · O 0.20% max · Fe 0.40% max · N 0.05% max · C 0.08% max · H 0.015% max · Y 0.005% max · each other element 0.10% max · other elements total 0.40% max · balance Ti. Density 4.42-4.43 g/cm3. Beta transus about 995-1000 °C. Unlike the commercially pure grades (1, 2 and 4) it DOES gain strength by SOLUTION TREATING AND AGEING (STA); this is a genuine heat-treatment hardening.
It is bought for aerospace structural and engine parts where strength-to-weight ratio and strength at moderate temperature are both required: airframe and wing attachment hardware, landing gear parts, compressor discs and blades, engine mounts, fasteners (bolts and nuts), pressure vessels, rocket…
Forms
Round bar · flat bar · plate · sheet · tube · forgings. All forms are supplied to order.
Standards
AMS (verified by four or more independent sources): 4911 – sheet, strip and plate, annealed · 4928 – bars, wire, forgings, rings and drawn shapes, annealed · 4965 – bars, wire, forgings and rings, SOLUTION HEAT TREATED AND AGED (STA) · 6931 – bars, forgings and forging stock, annealed. Military equivalents: AMS-T-9046 / MIL-T-9046 Type AB-1 (sheet, strip, plate) · AMS-T-9047 / MIL-T-9047 (bars and reforging stock). ASTM: B265 / ASME SB-265 Grade 5 (strip, sheet, plate) · B348 / ASME SB-348 Grade 5 (bars and billets) · B381 Grade F-5 (forgings) · F1472 (surgical implants, UNS R56400). Welding: matching ERTi-5 rod to AWS A5.16 / ASME SFA-5.16; where toughness is needed, ELI (ERTi-23) or unalloyed filler is also used (TWI). EVERY AMS NUMBER WAS VERIFIED ONE BY ONE. THOSE THAT BELONG TO GRADE 5: 4911 (sheet/strip/plate, annealed – 5 sources) · 4928 (bars/wire/forgings/rings, annealed – 6 sources) · 4965 (bars/wire/forgings/rings, solution heat treated and aged – 5 sources) · 6931…
Advantage
It is the only common titanium grade that gains strength by heat treatment, and the gain is measurable: in the annealed condition the ASTM B265 / B348 minimum yield is 828 MPa (120 ksi), while after solution treating and ageing (STA) the typical yield rises to between 1034 MPa (150 ksi, United…
Welding
Filler metal: matching ERTi-5 rod to AWS A5.16 / ASME SFA-5.16. TWI reports that UNALLOYED or ELI filler is used on alpha-beta alloys to raise weld metal ductility, by cutting the amount of beta phase and the interstitial load. PREHEAT IS NOT REQUIRED.
Limits
THE TEMPERATURE CEILING DIVIDES BY SOURCE: Carpenter Technology gives about 350 °C (660 °F), TIMET 350 °C (660 °F), Aubert & Duval 300 °C for creep and Granta / Titanium Information Group about 400 °C (750 °F). NO AVERAGE HAS BEEN TAKEN; a design must state which source’s criterion it uses.
Compiled from manufacturer data sheets · confirm against the current specification before ordering
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Standards by Product FormWelding, Heat Treatment and MachiningGrade 5 or Grade 5 ELI (Grade 23)?Frequently Asked Questions
Ti Grade 5 (Ti6Al4V) — Titanium – 6% Al – 4% V.
Properties: More than 50% of titanium products worldwide are produced from this alloy, by casting, powder metallurgy or hot forming. The properties of the various product forms depend on the chemical composition used and on the thermomechanical processing. The alloy is generally used in the annealed (soft annealed) condition, which gives the best combination of strength, toughness and ductility. The alloy can be age hardened in thicknesses up to 25 mm.
The alloy is formed from titanium combined with aluminium and vanadium. It is one of the most widely used types of titanium alloy and is chosen for many demanding applications because of properties such as high strength, low density and corrosion resistance.
It is ideal for applications requiring high performance in particular.
Application areas: chemical industry, aerospace industry, medical applications.
Machinability: The alloy is known for its high strength and hardness, which can make it somewhat difficult to machine. With the right techniques and tooling, however, it can be machined successfully.
Machining: It can be processed by operations such as milling, turning and drilling. Because of the high melting point and hardness of titanium, care should be taken to work at low speeds. Cutting tools should generally be a hard alloy or carbide, and cutting fluids should be used to prevent overheating.
Welding: The alloy is suitable for TIG (Tungsten Inert Gas) welding. Shielding with inert gases such as argon should be provided during welding, since titanium is sensitive to oxidation. MIG welding can also be applied, but it requires high precision.
Cold forming: The alloy is suitable for cold forming operations and can be shaped by processes such as plasma cutting and bending.
Hot forming: The alloy is suitable for hot forming, but it is important to prevent oxidation at high temperatures.
AMS 4965 – bars, wire, forgings and rings, SOLUTION HEAT TREATED AND AGED. AMS 4967 (annealed, heat treatable) and AMS 6930 (bars/forgings/forging stock, STA) belong to Grade 5 but were left off the card because they reached only three and two sources respectively.
Surgical implants
ASTM F1472 – Wrought Titanium-6Aluminum-4Vanadium Alloy for Surgical Implant Applications (UNS R56400). ASTM F136, the ELI implant specification, DOES NOT BELONG TO THIS GRADE.
Welding filler
Matching ERTi-5 rod to AWS A5.16 / ASME SFA-5.16. TWI reports that unalloyed or ELI (ERTi-23) filler may be used to raise weld metal ductility.
Inspection · Europe · certification
AMS 2631 – ULTRASONIC INSPECTION of titanium bar, billet and plate; it is NOT a material specification and names no grade. The split between W.Nr. 3.7165 (general) and 3.7164 (aerospace) rests on two sources. EN 10204 is not a material specification; it defines the 2.2 / 3.1 / 3.2 inspection document type.
AMS numbers are written first and ASTM numbers second. AMS 4907, 4930, 4931 and 6932 are ELI (Grade 23) numbers and DO NOT APPEAR in this map. No verified AMS pipe or tube number was found for Grade 5. Whether Grade 5 appears in ASTM B861 / B862 / B863 could not be verified by four sources and was written into the skipped list.
Two points are critical when ordering Ti Grade 5. First, different standards apply to different product forms, and aerospace (AMS) specifications impose a tighter iron limit than ASTM. Second, a common market error is to quote Grade 5 tube against “ASTM B338” — the ASTM B338 grade list does not include Grade 5; Grade 5 pipe is ordered to B861 / B862.
Standards by Product Form · Ti Grade 5 / Ti-6Al-4V (R56400)
Mechanical minimums to ASTM B265 / B348 Grade 5: tensile ≥ 895 MPa, 0.2% yield ≥ 828 MPa, elongation ≥ 10%. Density is 4.43 g/cm³ — about 57% that of steel. On chemistry, ASTM caps iron at 0.40% and AMS at 0.30%; oxygen is capped at 0.20% in both.
Welding, Heat Treatment and Machining
HEAT TREATMENT — SCHEMATIC
1 · SOLUTION TREATMENT
843-968 °C band. TIMET 899-968 °C (1650-1775 °F) TIMET 2-120 minutes
2 · COOL
WATER QUENCH. All four sources give a water quench. The quench freezes the beta phase in a supersaturated state through the section; air cooling is NOT SUFFICIENT for STA and a heavy section will not harden through at the centre.
3 · AGEING
see the table below
DEFENCE METAL
Solution treatment
Temperature
843-968 °C band. TIMET 899-968 °C (1650-1775 °F) · Granta/TIG 904-954 °C (1660-1750 °F) · NASA/DMIC 843-954 °C (1550-1750 °F) · RMI/RTI 954 °C (1750 °F). FOUR INDEPENDENT SOURCES. All lie BELOW the beta transus (995-1000 °C); NASA/DMIC states that the low end of the band (843 °C) is used for ductility and formability and the high end (927-954 °C) for maximum strength.
Time
TIMET 2-120 minutes · Granta/TIG 5 minutes to 2 hours · RMI/RTI 10 minutes · NASA/DMIC according to section thickness.
Cooling
WATER QUENCH. All four sources give a water quench. The quench freezes the beta phase in a supersaturated state through the section; air cooling is NOT SUFFICIENT for STA and a heavy section will not harden through at the centre.
Warning
NASA/DMIC reports an alpha case of 0.08-0.20 mm (3-8 mils) under typical solution-treating conditions in air. If vacuum or a protective atmosphere is not used, that layer must be removed.
DEFENCE METAL
1 · STRESS RELIEF
Step
1 · STRESS RELIEF
Summary
Reduces residual stress left by machining, cold forming, straightening and welding. It changes neither the grain structure nor the strength.
Temperature
482-649 °C. RMI/RTI 482 °C (900 °F) · NASA/DMIC 538-649 °C (1000-1200 °F). TWO INDEPENDENT SOURCES; four could not be reached, so this is not written as a binding band.
Time
RMI/RTI 30 minutes · NASA/DMIC 30 minutes to 1 hour.
Cooling
Air cool.
Resulting hardness
Hardness and strength are practically unchanged. Stress relief is NOT a hardening step.
DEFENCE METAL
2 · ANNEALING (MILL ANNEAL)
Step
2 · ANNEALING (MILL ANNEAL)
Summary
The standard as-delivered condition. The temperature stays below the beta transus and the equiaxed alpha plus intergranular beta structure is kept. The specification minima are written against this condition.
Temperature
704-816 °C common band. TIMET 704 °C (1300 °F) · RMI/RTI 704 °C (1300 °F) · Granta / Titanium Information Group 732 °C (1350 °F) · NASA/DMIC 704-816 °C (1300-1500 °F). FOUR INDEPENDENT SOURCES. NO AVERAGE HAS BEEN TAKEN.
TIMET air cool or slower · RMI/RTI air cool · NASA/DMIC furnace cool to about 593 °C (1100 °F), then air · Granta/TIG furnace cool to 566 °C (1050 °F), then air.
Annealing ABOVE the beta transus and cooling produces a transformed-beta (lamellar / Widmanstaetten) structure. Yield strength falls slightly while fracture toughness and crack growth resistance rise. It is not a strength step but a TOUGHNESS step.
Temperature
Above the beta transus. RMI/RTI gives 1016 °C (1860 °F). NeoNickel lists a ‘beta annealed’ condition separately but gives no temperature. TWO SOURCES; not written as a binding temperature.
Time
RMI/RTI 20 minutes. Single source.
Cooling
Air cool (transformed-beta structure).
Resulting hardness
NeoNickel gives 903 MPa (131 ksi) yield and 134 ksi-root-in K1C for the beta annealed condition, and 910-979 MPa (132-142 ksi) yield with 128-140 ksi-root-in K1C for continuously rolled annealed sheet. SINGLE SOURCE.
DEFENCE METAL
AGEING · LOW END (maximum strength)
Step
AGEING · LOW END (maximum strength)
Temperature
482-552 °C. TIMET low end of the band 482 °C (900 °F) · NASA/DMIC 482-593 °C (900-1100 °F) · United Performance Metals 524-552 °C (975-1025 °F) · Granta/TIG 538 °C (1000 °F) · NeoNickel 538 °C. FIVE INDEPENDENT SOURCES.
Time
1-24 hours. TIMET 2-8 hours · NASA/DMIC 1-24 hours, with no significant effect beyond 8 hours · Granta/TIG 4 hours.
Cooling
Air cool.
Result
Highest yield, lowest toughness. United Performance Metals gives 1034 MPa (150 ksi) yield and about 360 HBW after 524-552 °C; NeoNickel gives 1096 MPa (159 ksi) yield and 80 ksi-root-in K1C for 538 °C.
DEFENCE METAL
AGEING · HIGH END (towards toughness)
Step
AGEING · HIGH END (towards toughness)
Temperature
621-691 °C. RMI/RTI 621 °C (1150 °F) · TIMET high end of the band 691 °C (1275 °F) · NeoNickel 677 °C. THREE SOURCES.
Time
RMI/RTI 24 hours · TIMET 2-8 hours.
Cooling
Air cool.
Result
Yield falls and toughness rises: NeoNickel gives 945 MPa (137 ksi) yield and 105 ksi-root-in K1C for 677 °C. Within one alloy, the ageing temperature is what chooses between strength and toughness.
The diagram is schematic; the time axis is NOT to scale. No published TTT/CCT curve was used, so no curve is drawn. Ti-6Al-4V is an ALPHA-BETA alloy and, unlike the commercially pure grades, it DOES gain strength by SOLUTION TREATING AND AGEING (STA); this is a genuine heat-treatment hardening. The upper limit of every stage is set by the BETA TRANSUS: about 995-1000 °C (1825-1830 °F). Each stage below was verified separately and the source count is stated on every stage. STA = SOLUTION TREAT + WATER QUENCH + AGE. If any one of the three steps is left out, the result is not STA. A drawing that says only ‘heat treated’ is not enough; the solution temperature, the quench medium and the ageing temperature and time must each be written. THE STA EFFECT IS LIMITED BY SECTION THICKNESS: TIMET gives the STA cycle only for certain bar products. The sources DIVERGE on the beta transus: TIMET 996 °C (1825 °F ±25 °F) · United Performance Metals 999 °C (1830 °F ±25 °F) · Granta / Titanium Information Group 999 °C (±15 °C) · NeoNickel 996 °C (±28 °C). NO AVERAGE HAS BEEN TAKEN; the card writes the range 995-1000 °C. The stress relief and beta annealing stages did not reach four sources; the source counts are written inside the stages and those figures must not be used as a binding recipe. No published TTT/CCT curve was used; the diagram shows only the order of the cycle.
Welding
GTAW (TIG) is the most common and preferred process; GMAW, plasma, electron beam, laser and resistance welding are also used. The filler is matching AWS A5.16 ERTi-5 (AMS 4954), or ERTi-23 (ELI, AMS 4956) for a more ductile and tougher weld. Atmospheric contamination is the decisive issue with this material: pure argon shielding, back (root) purging and a trailing shield are mandatory — pick-up of oxygen, nitrogen or hydrogen embrittles the weld. Avoid iron contamination: use dedicated grinding wheels and brushes and clean gloves. All surface oxide and grease must be removed before welding. Post-weld stress relief is recommended.
Heat treatment
Ti-6Al-4V is an α+β alloy with a β-transus of roughly 995–1000 °C. The standard delivery condition is mill annealed: 705–760 °C, typically 730 °C, for 0.5–4 hours, air or furnace cooled. Stress relief is carried out between 540 and 650 °C for 1–8 hours. Where higher strength is required, solution treatment and ageing (STA) is applied: for bar and forgings, 955 ± 14 °C for 2 hours followed by water quenching, then ageing at 525–550 °C for 4–8 hours. The effectiveness of STA depends strongly on section thickness — above roughly 25–50 mm the quench rate becomes insufficient. STA material must be ordered separately to AMS 4965. Heat treatment must be carried out in vacuum or an inert atmosphere; treating in air forms a brittle oxygen-rich “alpha case” that has to be removed mechanically.
Machining
Machinability rating is roughly 20–22% of B1112. The governing rule is low cutting speed, high feed, sharp tooling and copious coolant. Typical speeds with coated carbide: turning 70–90 m/min, milling and drilling 50–70 m/min. Thermal conductivity is very low, so heat concentrates at the cutting edge — high-pressure, high-volume coolant directed straight at the edge is essential. Use a chlorine-free cutting fluid; chlorine residue creates a risk of stress-corrosion cracking. Rigid clamping is mandatory, since vibration causes sudden tool failure, and dwelling in the cut work-hardens the surface. Fine chips and dust ignite readily: do not let chips accumulate and keep a Class D extinguisher on hand.
Grade 5 or Grade 5 ELI (Grade 23)?
The difference between the two grades comes down to one thing: interstitial element levels, principally oxygen and iron. The alloying elements (Al and V) are identical.
In short, ELI gives up roughly 7% strength in exchange for markedly better ductility, fracture toughness and cryogenic performance. Buying ELI for a simple strength application is money wasted. For detail see Ti Grade 5 ELI · Ti Grade 2.
Frequently Asked Questions
I ordered ASTM B348 Grade 5 and received an AMS 4928 certificate. Is that acceptable?
Generally yes, but only in one direction. For bar, wire and forgings AMS 4928 imposes a tighter iron limit than ASTM B348 (0.30% versus 0.40%) along with additional inspection and traceability requirements. AMS 4928 material therefore satisfies B348 Grade 5; the reverse is not true — B348-certified material does not automatically substitute for AMS 4928. For aerospace work always order to AMS; dual-certified material is the safest option.
Can Grade 5 be used above 400 °C?
Not for continuous service. The upper limit quoted by manufacturers is 350–400 °C, for two reasons: at 427 °C the yield strength falls by roughly 40% relative to room temperature, and long exposure in air at high temperature forms a brittle oxygen-rich surface layer that shortens fatigue life. Short-term, intermittent exposure can go higher subject to engineering assessment, but should not be taken as a continuous design value.
Can I order Grade 5 tube to ASTM B338?
No. This is a common market error: the ASTM B338 grade list does not include Grade 5. Grade 5 seamless pipe is ordered to ASTM B861 and welded pipe to ASTM B862. Note also that AMS 4945 and AMS 4946 are not Ti-6Al-4V — they are Ti-3Al-2.5V hydraulic tubing specifications, which some supplier listings show incorrectly.
AMS 4911 – annealed sheet, strip and plate, 4.76-101.6 mm
–
823
893
10%
AMS 4928 – annealed bars, wire, forgings and rings
–
828
931
10%
ANNEALED (MILL ANNEALED) – typical values
334 HBW / 36 HRC
828
903
10-18%
BETA ANNEALED
–
903
–
–
SOLUTION TREATED AND AGED (STA) – low-end ageing (524-552 °C)
about 360 HBW
1034-1096
–
–
SOLUTION TREATED AND AGED (STA) – high-end ageing (677 °C)
–
945
–
–
ASTM F1472 – surgical implant, annealed
–
860
930
10%
In the chart, a value given as a range is drawn at its lower bound; the full range is in the table. SPECIFICATION MINIMA and TYPICAL VALUES are not mixed in the same table; the ‘Source type’ field of each row states which it is. The STA rows are TYPICAL values. ASTM B265 / B348 Grade 5 is written against the annealed condition and gives no separate floor for STA; the STA floor comes from AMS 4965 and AMS 6930, whose numerical content could not be verified by four sources. The fracture toughness (K1C) values come from a single source (NeoNickel) and no separate diagram was made; they are given as information in the row notes.
COMPARISON
A single criterion: SPECIFICATION CEILINGS and SPECIFICATION FLOORS (not typicals). Chemical ceilings from Table 1 of ASTM B265 / B348, tensile values from Table 2; the implant rows from ASTM F1472 and ASTM F136. The product condition is annealed. Producer typicals run above these floors.
DEFENCE METAL
Grade
UNS
W.-Nr.
Standard
Aluminium
Vanadium
Oxygen max
Iron max
Nitrogen max
Carbon max
Hydrogen max
Tensile min MPa
Yield min MPa
Elongation min
Note
Ti Grade 5 (Ti-6Al-4V)
UNS R56400
3.7165
ASTM B265 / B348 Grade 5
5.5-6.75%
3.5-4.5%
0.20%
0.40%
0.05%
0.08%
0.015%
895
828
10%
Aerospace structural grade. Gains strength by solution treating and ageing (STA).
Ti Grade 23 (Ti-6Al-4V ELI)
UNS R56407
3.7165
ASTM B265 / B348 Grade 23
5.5-6.5%
3.5-4.5%
0.13%
0.25%
0.03%
0.08%
0.0125%
828
759
10%
ELI = Extra Low Interstitial. Interstitial elements are cut back for fracture toughness and cryogenic behaviour.
Ti-6Al-4V – surgical implant (ASTM F1472)
UNS R56400
–
ASTM F1472
5.5-6.75%
3.5-4.5%
0.20%
0.30%
0.05%
0.08%
0.015%
930
860
10%
The iron ceiling drops from 0.40% in B348 to 0.30%. THIS ROW RESTS ON A SINGLE SOURCE (GE Additive / Arcam).
Ti-6Al-4V ELI – surgical implant (ASTM F136)
UNS R56401
–
ASTM F136
5.5-6.5%
3.5-4.5%
0.13%
0.25%
0.05%
0.08%
0.012%
860
795
10%
The NITROGEN ceiling is HIGHER than in B265/B348 Grade 23 (0.05% against 0.03%); the hydrogen ceiling is lower (0.012%).
DEFENCE METAL
Additional information
Iliski
THE TWO GRADES ARE THE SAME ALLOY: the Al and V ranges are almost identical (the upper Al limit drops from 6.75% to 6.5%). THE DIFFERENCE LIES ONLY IN THE INTERSTITIAL CEILINGS: oxygen falls from 0.20% to 0.13% (-35%), iron from 0.40% to 0.25% (-37.5%), nitrogen from 0.05% to 0.03% (-40%) and hydrogen from 0.015% to 0.0125% (-17%). The price is strength: the minimum tensile falls from 895 MPa to 828 MPa (-7.5%) and the minimum yield from 828 MPa to 759 MPa (-8.3%). What is bought is fracture toughness, fatigue crack growth resistance and low-temperature ductility.
Mechanism
Oxygen and nitrogen enter the octahedral interstitial sites of the hexagonal close-packed alpha lattice and create an asymmetric lattice distortion; the resulting stress field impedes dislocation glide (interstitial solid solution strengthening). Strength rises while the capacity for plastic deformation at a crack tip falls, so fracture toughness and low-temperature ductility go down. Iron stabilises the beta phase and can segregate to grain boundaries. That is why all four ceilings are lowered together in ELI; ELI is NOT a separate alloy but the same alloy held to a narrower interstitial band.
Warning
THE UNS NUMBERS ARE EASILY CONFUSED: Grade 5 = R56400. On the ELI side there are TWO numbers – ASTM B265 / B348 Grade 23 = UNS R56407, and ASTM F136 (surgical implants) = UNS R56401. They are the same alloy but the nitrogen and hydrogen ceilings differ. If an order says only ‘Ti-6Al-4V ELI’ it is undefined which ceiling applies; the specification number and the grade number must be written together.
The iron ceiling in the ASTM F1472 row (0.30%) and the tensile/yield floors in the ASTM F136 row (860 / 795 MPa) come from a SINGLE SOURCE (GE Additive / Arcam); they were not confirmed by four sources. The ASTM B265 / B348 Grade 23 floors (828 / 759 MPa) were verified by two independent sources (TIMET, United Performance Metals); four sources could not be reached. The United Performance Metals table shows that ASTM F136 gives lower values for heavy sections (above 44.45 mm); the card does not write a single floor.
