AMS 4928 is the SAE aerospace material specification for annealed Ti-6Al-4V bar, wire, forgings and rings, UNS R56400. It covers the same 6% aluminum, 4% vanadium alloy as ASTM B348 Grade 5, but tightens the iron and hydrogen limits and adds aerospace-level process control, testing and traceability. This guide explains what AMS 4928 actually requires, how it differs from B348 Grade 5 and AMS 4911, and how to put a bar or machined-part RFQ together so it can be quoted without a second round of questions.
Beiyu Titanium supplies Ti-6Al-4V (Grade 5) bar and machined components for industrial, motorsport and performance applications, with EN 10204 3.1 mill test certificates and heat-number traceability; supply certified to AMS 4928 Ti-6Al-4V bar is reviewed per order.
What is AMS 4928, and what does it cover?
AMS 4928 is a SAE Aerospace Material Specification that defines Ti-6Al-4V in the annealed condition for wrought product: bar, wire, forgings and rings. The alloy is UNS R56400, the standard-interstitial version of Ti-6Al-4V, the same alloy sold industrially as ASTM B348 Grade 5.
What the AMS designation buys is not a different alloy but a different level of control. Where ASTM B348 is a general industrial standard, AMS 4928 layers on aerospace process requirements: tighter chemistry ceilings, defined testing, and traceability from the melt. A drawing that names AMS 4928 is asking for a documented pedigree, not just Grade 5 chemistry. For where this alloy sits among the common titanium grades, see our titanium grades comparison guide.
AMS 4928 vs ASTM B348 Grade 5: which one do you order?
This is the decision most buyers actually face, because both are Ti-6Al-4V at UNS R56400 with similar strength. The alloy is the same; the requirements around it are not:
| Requirement | AMS 4928 (aerospace) | ASTM B348 Grade 5 (industrial) |
|---|---|---|
| UNS number | R56400 | R56400 |
| Aluminum | 5.5 to 6.75% | 5.5 to 6.75% |
| Vanadium | 3.5 to 4.5% | 3.5 to 4.5% |
| Iron, max | 0.30% | 0.40% |
| Oxygen, max | 0.20% | 0.20% |
| Hydrogen, max | 0.0125% | 0.015% |
| Nitrogen / Carbon, max | 0.05% / 0.08% | 0.05% / 0.08% |
| Scope beyond chemistry | Aerospace process control, testing, melt traceability | General industrial bar and billet |
Confirm exact limits against the current revision of each standard; the certificate decides which requirement the material meets.
The buyer rule follows from the table. If the drawing calls out AMS 4928, then B348 Grade 5 material does not satisfy it, even though the alloy is identical, because the AMS pedigree and paperwork are part of the requirement. If the drawing does not name AMS and the part is an industrial or general performance component, B348 Grade 5 usually meets the need at a lower cost. Order to the standard the drawing names, and if none is named, ask which pedigree the application really requires before paying for the aerospace layer.
What are the AMS 4928 mechanical minimums, and what about hardness?
AMS 4928 sets minimum tensile properties that step down with section size, because larger cross sections cool and work differently:
| Section size (round or equivalent) | Tensile strength, min | Yield strength, min | Elongation, min (Long / LT / ST) | Reduction of area, min (Long / LT / ST) |
|---|---|---|---|---|
| Up to 2.000 in | 135 ksi (931 MPa) | 125 ksi (862 MPa) | 10% / 10% / not applicable | 25% / 20% / not applicable |
| Over 2.000 to 4.000 in | 130 ksi (896 MPa) | 120 ksi (827 MPa) | 10% / 10% / 10% | 25% / 20% / 15% |
| Over 4.000 to 6.000 in | 130 ksi (896 MPa) | 120 ksi (827 MPa) | 10% / 10% / 8% | 20% / 20% / 15% |
| Over 6.000 to 10.000 in | 130 ksi (896 MPa) | 119 ksi (820 MPa) | 10% / 10% / 8% | 20% / 20% / 15% |
All values are per AMS 4928 for the annealed condition; the mill test certificate reports the actual results by heat and size. AMS 4928 notes typical use for parts requiring moderate strength with maximum service temperature roughly 750 to 900°F (399 to 510°C), depending on time at temperature, but the drawing and service environment still decide the acceptance basis.
If the drawing is still deciding the heat-treatment route, compare annealed and solution-treated-and-aged titanium bar before locking the mechanical-property basis.
On hardness: AMS 4928 does not specify a hardness value. It controls tensile strength, yield, elongation and reduction of area, not hardness. As a reference, annealed Ti-6Al-4V typically runs around 30 to 36 HRC (roughly 300 to 350 HB), but that is a typical property, not a spec limit, so it should not go into an RFQ as a requirement. The tighter hydrogen ceiling also matters for high-load parts; for how hydrogen and grain size are measured and accepted on bar, see our guide to titanium bar grain size and hydrogen control.
For machining planning, account separately for why Ti-6Al-4V galls and work-hardens; those cutting considerations are not hardness acceptance limits under AMS 4928.
AMS 4928 vs AMS 4911 and the other Ti-6Al-4V specs
A common mix-up is AMS 4928 against AMS 4911. Both cover annealed Ti-6Al-4V at R56400; the difference is product form. AMS 4928 is the bar, wire, forging and ring spec, while AMS 4911 covers sheet, strip and plate. Order 4928 for round bar and machining stock, and 4911 for flat-rolled product. Here is how the equivalents line up:
| Ti-6Al-4V product form | Governing specification |
|---|---|
| Bar, wire, forging, ring (annealed) | AMS 4928 |
| Sheet, strip, plate (annealed) | AMS 4911 |
| Bar and billet (industrial) | ASTM B348 Grade 5 |
| Forgings (industrial) | ASTM B381 Grade F-5 |
| Common designations | UNS R56400, Grade 5, W.-Nr. 3.7165 |
So the AMS 4928 equivalent depends on what you mean: same alloy, different form is AMS 4911; same alloy, industrial pedigree is ASTM B348 Grade 5. If you are still choosing between commercially pure and alloy grades on strength and cost, our CP titanium grade selection guide covers where Grade 5 fits.
When do performance and motorsport parts need AMS 4928?
Ti-6Al-4V to AMS 4928 is the aerospace-grade wrought bar that high-load performance parts are machined from when a drawing calls for a certified pedigree. In practice, European performance and motorsport buyers procure machined Ti-6Al-4V components specified to AMS 4928 for strength-critical parts where weight and fatigue life matter and the design references the aerospace spec.
The practical question for any performance build is whether the drawing genuinely requires that aerospace layer or only the alloy, since a part with no AMS call-out can usually run on Grade 5 to ASTM B348 at lower cost and shorter lead time.
How is AMS 4928 different from medical F136 Ti-6Al-4V?
Both AMS 4928 and ASTM F136 are Ti-6Al-4V, but they are different grades of it for different worlds, and they are not interchangeable:
- AMS 4928 is standard-interstitial Ti-6Al-4V, UNS R56400, with oxygen up to 0.20%, for structural, aerospace, industrial and performance parts.
- ASTM F136 is Ti-6Al-4V ELI (extra-low interstitial), Grade 23, UNS R56401, with oxygen capped near 0.13% for higher fracture toughness in surgical implants.
A performance or industrial part built to AMS 4928 should not be switched to implant ELI material, and an implant should not be machined from AMS 4928 standard-interstitial bar; the UNS number on the certificate has to match the drawing. For implant-grade material, see our companion guide, ASTM F136 Ti-6Al-4V ELI bar.
If the certificate language still needs to be reconciled across AMS, ASTM, EN 10204 and Werkstoff terminology, use our Grade 5 titanium certification guide before the RFQ is released.
How do you specify and certify AMS 4928 bar or machined parts?
A complete Ti-6Al-4V line states the specification, form, size and pedigree so the mill can confirm fit on the first pass:
| RFQ item | Typical performance or industrial call-out | Why it matters |
|---|---|---|
| Specification | AMS 4928, or ASTM B348 Grade 5 if AMS is not required | Sets the testing and traceability level |
| Form | Round or rectangular bar, or a machined part to drawing | Determines the mill and machining route |
| Size and tolerance | Bar diameter and length, or finished dimensions and tolerance | Feeds machining without a cleanup pass |
| Condition | Annealed | Property and machinability baseline |
| Mechanical minimums | Per AMS 4928 for the section size | Confirmed on the certificate, not at goods-in |
| Certification | EN 10204 3.1 MTC with chemistry and mechanicals tied to the heat number | Traceability and acceptance |
State the specification exactly as the drawing does, because AMS 4928 and B348 Grade 5 are the same alloy but not the same order; give bar size and tolerance, or the finished-part drawing, so machining allowance is right.
Beiyu supplies Ti-6Al-4V (Grade 5) bar and machined components for industrial, motorsport and performance applications, with EN 10204 3.1 mill test certificates and heat-number traceability by order scope. The producing mill operates a documented quality system, and its certificates accompany the material so the certificate entity matches the mill on the MTC. Whether a given order can be supplied certified to AMS 4928 is reviewed per order against the drawing and pedigree required.
For repeat orders, review how heat-to-heat variation in Ti-6Al-4V ingots can affect the actual chemistry and mechanical results reported against the same specification limits.
What does the annealed condition actually mean for AMS 4928 bar?
AMS 4928 covers Ti-6Al-4V in the annealed condition, and for a buyer the word annealed carries two practical promises. The first is a predictable microstructure: an alpha-beta structure processed below the beta transus, which for Ti-6Al-4V sits at about 995 °C, giving the balanced strength, ductility and machinability the specification’s minimums assume. The second is dimensional stability on the machine: annealed bar has lower residual stress than as-rolled material, so it moves less when a machinist takes heavy cuts. What annealed does not promise is the higher strength of the solution-treated-and-aged (STA) condition; parts that need STA properties run under a different specification and a different heat-treatment route, and the two are not interchangeable line items. If a drawing calls for heat treatment after machining, say so on the RFQ, because the mill’s anneal and the part maker’s downstream treatment have to be planned as one route.
What about AMS 4965, the solution treated and aged version?
AMS 4965 covers the same Ti-6Al-4V alloy as AMS 4928, but in the solution treated and aged condition rather than annealed. STA raises tensile and yield strength, so AMS 4965 appears on drawings where annealed Grade 5 strength is not enough. The two are not interchangeable on a certificate: state the specification and the condition together on the RFQ, annealed to AMS 4928 or STA to AMS 4965, along with grade, size and the test package the order requires.
Machining and fabrication behaviour buyers should plan for
Ti-6Al-4V machines well with the right setup and punishes the wrong one. The alloy conducts heat poorly and its cut surface hardens when a tool rubs or dwells instead of cutting, so the working rules are low cutting speed, steady positive feed, rigid fixturing and generous coolant. The full mechanism, and why the same behaviour shows up as galling in service, is covered in our guide to why Ti-6Al-4V galls and work-hardens. Two planning consequences follow for procurement. First, order machining allowance: enough stock to remove the surface layer and reach clean parent metal, especially where the drawing carries tight surface-integrity requirements. Second, if the part will be welded, plan full inert-gas shielding of the heated zone, because titanium picks up oxygen and nitrogen fast at welding temperature and embrittles; weld colour is the working indicator, as set out in the titanium weld colour chart.
Service temperature and environment limits
Annealed Ti-6Al-4V holds useful strength to roughly 350 to 400 °C depending on load and duration, with long-term, creep-limited service usually planned more conservatively and strength falling progressively above that range. On the environment side, the alloy’s oxide film gives strong resistance in neutral and oxidising media, seawater included, but Ti-6Al-4V is not the corrosion workhorse of the family: for hot reducing acids and aggressive chloride crevices, the corrosion grades, Grade 7 and Grade 12, are the honest recommendation, and Ti-6Al-4V is chosen where the driver is strength. Above roughly 600 °C in air titanium begins to form the oxygen-enriched surface layer known as alpha case, with growth becoming practically significant at hot-working temperatures; the layer is brittle, it matters mainly for hot processing rather than service, and it is why forged or hot-worked surfaces are machined or pickled back to parent metal.
Storage, handling and contamination control
Titanium bar does not rust, but it can be contaminated. The receiving-side rules cost little and prevent audit findings later: store titanium separated from carbon steel so grinding sparks and steel dust do not embed iron in the surface; keep it clear of chloride sources; and if a job site also runs steel, dedicate tools or clean between materials, because embedded iron shows up later as rust staining and, on certified work, as a failed surface-iron check. Keep heat-number marking legible through storage, since a bar that loses its identity loses its certificate with it. Bundles should stay strapped and end-protected until use.
Limitations and failure modes worth knowing before you order
An honest specification sheet includes what the material does badly.
- Fatigue lives or dies at the surface. Ti-6Al-4V is notch-sensitive; machining marks, embedded contamination and un-removed alpha case cut fatigue life far more than a few MPa of tensile strength ever adds. Surface condition callouts do more for a cyclically loaded part than grade upgrades.
- Hydrogen pickup is a processing risk. Over-aggressive pickling or poorly controlled chemical cleaning loads hydrogen into the surface, and hydrogen embrittles titanium; this is controlled at the mill and should stay controlled downstream. The mechanism is covered in the grain size and hydrogen control guide.
- Galling in service. Titanium-on-titanium fasteners and sliding fits gall without lubrication or surface treatment; design around it rather than discovering it at assembly.
- It is not the toughness champion. Where damage tolerance and fracture toughness lead the requirement, the extra-low-interstitial Grade 23 exists for exactly that trade, as covered in the Grade 5 certification guide.
Procurement notes from the export desk
Three habits make AMS 4928 orders land cleanly. Send the drawing note verbatim, revision letter included, because AMS revisions move and a paraphrased callout is how a mismatch gets built into an order. Check the size band: AMS 4928 minimums step with section size, so confirm the guaranteed numbers for your diameter rather than quoting the headline figures. And where a project sits between the industrial and AMS worlds, ask for dual certification to ASTM B348 and AMS 4928 up front; certifying both at production is routine, re-certifying after delivery is not. Beiyu reviews each AMS 4928 enquiry line against mill capability before quoting, with EN 10204 3.1 documentation and heat-number traceability by order scope.
Frequently asked questions
What is AMS 4928?
AMS 4928 is the SAE aerospace material specification for annealed Ti-6Al-4V (UNS R56400) in bar, wire, forging and ring form. It sets the alloy chemistry, tensile and yield minimums by section size, and aerospace-level testing and traceability. It is the certified-pedigree route for the same alloy sold industrially as ASTM B348 Grade 5.
AMS 4928 vs ASTM B348 Grade 5: are they interchangeable?
The alloy is identical (Ti-6Al-4V, R56400), but the specifications are not interchangeable. AMS 4928 adds tighter iron and hydrogen limits, aerospace process control and melt traceability, so B348 Grade 5 does not satisfy an AMS 4928 call-out. Where no AMS is named, B348 Grade 5 usually meets industrial and performance needs more economically.
What is the AMS 4928 equivalent?
For the same alloy in flat product, the equivalent is AMS 4911 (sheet, strip, plate). For the same alloy at industrial pedigree, it is ASTM B348 Grade 5 (bar and billet) or ASTM B381 F-5 (forgings). All share UNS R56400 and the designation W.-Nr. 3.7165.
Does AMS 4928 specify a hardness?
No. AMS 4928 controls tensile strength, yield, elongation and reduction of area, not hardness. Annealed Ti-6Al-4V typically measures around 30 to 36 HRC, but that is a typical property rather than an acceptance requirement, so hardness should not be written into an AMS 4928 order as a spec limit.
References
- SAE AMS 4928, Titanium Alloy Bars, Wire, Forgings, Rings, and Drawn Shapes, 6Al-4V, Annealed: sae.org/standards/content/ams4928
- ASTM B348, Standard Specification for Titanium and Titanium Alloy Bars and Billets: astm.org/b0348
- EN 10204, Metallic products, types of inspection documents (CEN)
Request a quote for AMS 4928 Ti-6Al-4V bar
Use the titanium bar RFQ checklist to confirm the specification, condition, dimensions, tolerance, quantity and MTC scope before submission.
To quote Ti-6Al-4V for a performance or industrial part, Beiyu needs: specification (AMS 4928 or ASTM B348 Grade 5), form (bar or machined part), size and tolerance (bar diameter and length, or the finished drawing), condition, mechanical minimums, and quantity. Send the drawing or spec and we review each line against mill and machining capability before quoting, with EN 10204 3.1 MTC and heat-number traceability by order scope. Contact Beiyu Titanium for an RFQ.