Aerospace Titanium Standards: AMS 4928, AMS 4911, ASTM B348 and Ti-6Al-4V at Farnborough Airshow
The aerospace industry places some of the most demanding requirements on metallic materials. Strength, weight, corrosion resistance, fatigue performance, traceability and consistency all matter when components are being manufactured for aircraft and other aerospace applications.
One material that continues to play an important role across the industry is titanium, particularly Ti-6Al-4V, commonly known as Titanium Grade 5.
During a visit to the Farnborough International Airshow, I took the opportunity to look at the aerospace industry from a materials and manufacturing perspective.
In the video below, I explore the show while highlighting some of the titanium specifications that engineers, buyers, machinists, stockholders and aerospace manufacturers regularly encounter.
Why Is Titanium Used in Aerospace?
Titanium offers an attractive combination of properties for aerospace applications.
It provides a high strength-to-weight ratio, excellent corrosion resistance and good performance across demanding operating environments. This makes titanium particularly useful where reducing weight is important without sacrificing mechanical performance.
Titanium can be found in applications ranging from structural components and fasteners to engine components, hydraulic systems and other critical aircraft assemblies.
However, specifying a material simply as “titanium” or even “Ti-6Al-4V” is usually not enough.
The aerospace industry relies on detailed material specifications defining the alloy, product form, condition, mechanical properties, manufacturing route, testing and certification requirements.
Ti-6Al-4V – Titanium Grade 5
One of the most widely recognised titanium alloys is Ti-6Al-4V.
The alloy contains approximately 6% aluminium and 4% vanadium, with titanium making up the balance.
It is commonly known commercially as Titanium Grade 5, although aerospace purchasing specifications will usually reference a more specific material standard.
Two specifications that frequently appear when searching for aerospace Ti-6Al-4V are:
AMS 4928
AMS 4911
The correct specification depends heavily on the product form being supplied.
AMS 4928 – Ti-6Al-4V Bar, Billet and Forging Stock
AMS 4928 is one of the key specifications associated with Ti-6Al-4V material supplied in forms such as bar, billet and forging stock.
For companies machining aerospace components, titanium bar is an important raw material.
Typical searches from buyers and engineers include:
AMS 4928 titanium bar
AMS 4928 Ti-6Al-4V
AMS 4928 round bar
aerospace titanium bar
Grade 5 titanium aerospace material
A critical point for buyers is that specifying Ti-6Al-4V alone does not necessarily mean a material automatically meets AMS 4928.
The required aerospace specification should always be checked against the manufacturer’s certification and the requirements of the component drawing or purchase order.
AMS 4911 – Ti-6Al-4V Sheet, Strip and Plate
Where Ti-6Al-4V is required in flat product form, AMS 4911 is another important aerospace specification.
It is commonly associated with Ti-6Al-4V supplied as:
Titanium sheet
Titanium strip
Titanium plate
This makes AMS 4911 an important specification for manufacturers producing fabricated or machined aerospace components from flat titanium material.
Common search terms include:
AMS 4911 titanium sheet
AMS 4911 titanium plate
AMS 4911 Ti-6Al-4V
aerospace titanium sheet
Grade 5 titanium plate
Again, product form matters. A Ti-6Al-4V bar specification and a Ti-6Al-4V sheet specification are not automatically interchangeable simply because the underlying alloy chemistry is similar.
ASTM B348 – Titanium Bar and Billet
Another specification frequently encountered in the titanium industry is ASTM B348.
ASTM B348 covers titanium and titanium alloy bars and billets and is commonly used when specifying titanium long products.
You may therefore encounter material described as:
ASTM B348 Grade 5 Titanium
This identifies Ti-6Al-4V supplied under the requirements of the ASTM B348 specification.
However, aerospace users should distinguish between ASTM material specifications and the specific AMS requirements called up by an aerospace drawing, customer or OEM.
An ASTM B348 Grade 5 bar should not automatically be assumed to meet AMS 4928 unless it has been manufactured, tested and certified accordingly.
ASTM B265 – Titanium Sheet, Strip and Plate
For flat titanium products, ASTM B265 is another widely recognised specification.
It covers titanium and titanium alloy:
Plate
Sheet
Strip
A buyer searching for ASTM B265 Grade 5 titanium plate, for example, is generally looking for Ti-6Al-4V flat product manufactured to that ASTM specification.
For aerospace applications, it remains important to check whether ASTM B265 is acceptable or whether the drawing specifically requires an AMS aerospace specification such as AMS 4911.
Titanium Tubing for Aerospace
Titanium tube is another significant product category, particularly in aerospace fluid systems and other applications where low weight and corrosion resistance are valuable.
Specifications can vary substantially depending on the alloy and intended use.
ASTM B338 is one recognised specification covering certain titanium and titanium alloy tubing, while aerospace applications may call for dedicated AMS tubing specifications.
This highlights an important principle when purchasing aerospace titanium:
The alloy is only part of the specification. The product form and required standard are equally important.
A request for “Grade 5 titanium tube”, for example, needs to be narrowed down to the required dimensions, manufacturing method, condition, testing requirements and applicable aerospace specification.
AMS vs ASTM Titanium Specifications
One of the most common sources of confusion when sourcing titanium is the difference between an alloy grade and a material specification.
Consider these descriptions:
Ti-6Al-4V describes an alloy.
Titanium Grade 5 is a widely used grade designation for Ti-6Al-4V.
ASTM B348 Grade 5 describes Grade 5 titanium supplied as bar or billet to ASTM B348 requirements.
AMS 4928 specifies Ti-6Al-4V material under a particular aerospace material specification.
They may all relate to Ti-6Al-4V, but they should not automatically be treated as identical purchasing requirements.
For aerospace procurement, always work from the specification stated on the engineering drawing, customer requirement or purchase order.
Titanium Product Forms Used by Aerospace Manufacturers
Aerospace titanium suppliers commonly provide material in a variety of forms, including:
Titanium round bar – used extensively for machining aerospace components.
Titanium billet – used as starting material for forgings and other manufacturing processes.
Titanium plate – used for larger machined or fabricated components.
Titanium sheet – used where thinner sections or fabricated structures are required.
Titanium tube – used across specialist aerospace systems and assemblies.
Titanium forgings – used for components requiring controlled grain structure and high mechanical performance.
Each product form can have its own applicable AMS, ASTM or customer-specific specification.
Why Material Certification and Traceability Matter
In aerospace supply chains, the specification printed on an enquiry is only the beginning.
Material traceability is extremely important.
Buyers may need to verify information including:
Material specification
Alloy and grade
Heat or melt number
Chemical composition
Mechanical properties
Heat treatment condition
Manufacturing route
Testing and inspection results
Country of origin
Manufacturer
Material certification
The exact requirements depend on the customer, application and applicable quality system.
This is why aerospace material sourcing is considerably more involved than purchasing a piece of metal based only on dimensions and alloy.
Aerospace Manufacturing at Farnborough International Airshow
Farnborough International Airshow provides an interesting opportunity to see just how extensive the modern aerospace supply chain has become.
Behind every finished aircraft is an enormous network of material producers, stockholders, forgers, machinists, fabricators, surface treatment companies, testing laboratories, equipment manufacturers and specialist engineering businesses.
Titanium is just one part of that supply chain, but it demonstrates how tightly controlled aerospace materials can be.
For suppliers looking to enter or expand within aerospace manufacturing, understanding specifications such as AMS 4928, AMS 4911, ASTM B348 and ASTM B265 is an important starting point.
Key Aerospace Titanium Specifications
For anyone beginning their research, some of the important terms worth understanding include:
AMS 4928 – Ti-6Al-4V bar, billet and forging stock
AMS 4911 – Ti-6Al-4V sheet, strip and plate
ASTM B348 – Titanium and titanium alloy bar and billet
ASTM B265 – Titanium and titanium alloy sheet, strip and plate
ASTM B338 – Titanium and titanium alloy tubing for covered applications
Ti-6Al-4V – One of the most widely used titanium alloys
Titanium Grade 5 – Common grade designation for Ti-6Al-4V
Final Thoughts
If you are buying, machining or supplying titanium for aerospace applications, understanding the exact material specification is essential.
Two pieces of material can both be described as Ti-6Al-4V Grade 5, but that does not necessarily mean they meet the same aerospace specification.
Always consider:
Alloy + Product Form + Condition + Specification + Certification
rather than alloy alone.
Watch the video above for a look around the Farnborough International Airshow and a broader view of the aerospace manufacturing industry where materials such as titanium play such an important role.
