Grade 23 titanium

Identity and designation boundaries

Grade 23 generally identifies Ti-6Al-4V ELI, the extra-low-interstitial variant. ATI describes lower oxygen, carbon and iron than its standard Ti-6Al-4V product. Specify the complete alloy and product requirements. ATI: 6-4 ELI technical sheet

ATI's sheet identifies UNS R56407; ASTM F136-26 identifies UNS R56401 for its wrought annealed implant-alloy scope. Preserve these source-specific associations rather than inferring a universal cross-reference or dual certification. Check the ordered standard, edition, form, condition and delivered certificate. ATI: Grade 23 identification, ASTM: F136-26

“ELI” also does not prove producer provenance, melting route, powder cleanliness, implant suitability or finished-part performance. Keep the exact manufacturer, product and traceability in the material record, especially when a supplier offers a substitution under a similar trade description.

Wrought material versus implant qualification

ASTM F136-26, updated 9 February 2026, covers chemical, mechanical and metallurgical requirements for wrought annealed Ti-6Al-4V ELI used to manufacture surgical implants. Its product classes include strip, sheet, plate, bar, forging bar and wire. It is a material specification, not approval of every finished implant design or manufacturing process. Its scope also requires SI and inch-pound systems to be used independently rather than mixing values to establish conformance. ASTM: F136-26 scope and abstract

For another application or product form, select the applicable specification rather than using “implant grade” as a substitute. A machined bar part, thin strip component and additively manufactured part require different evidence about microstructure, defects, surface condition and processing history. Identify which requirements are contractual and which are merely supplier typical data.

A bounded thin-product example

AMETEK's Titanium 6Al-4V ELI (Grade 23) Strip sheet, printed V3.12.22, describes sheet 0.005–0.020 inch thick. Its composition table lists aluminum 5.5–6.5%, vanadium 3.5–4.5%, oxygen 0.13% maximum and iron 0.25% maximum, among other controlled elements. Those figures belong to that product document, not every specification using an ELI description. AMETEK: Grade 23 strip sheet

The footnote warns that measured elongation decreases as thickness reaches 0.005 inch and below. The document characterizes its data as guidance and allows process-variable adjustment; obtain the required acceptance values and complete test protocol for the order. Do not apply the thin-sheet table to a thick forging or weld deposit. AMETEK: annealed properties and notes

The lower interstitial limits do not eliminate the need for mechanical tests. Confirm specimen orientation, gauge length, product dimensions and heat-treated condition when comparing results. Elongation, proof strength, fatigue and fracture toughness are different properties; choosing the largest tensile number is not a complete material-selection method.

Microstructure, fatigue and thermal history

Carpenter's Ti 6Al-4V ELI guidance distinguishes mill-, beta- and recrystallization-annealed structures, with different strength, ductility and damage-tolerance aims. It emphasizes that high-cycle fatigue depends on microstructure and surface condition. Preserve those conditions when using a fatigue curve rather than treating “Grade 23” as a single fatigue allowable. Carpenter: ELI microstructure and mechanical guidance

The same source explains that heating in air can produce an oxygen-enriched, hard and brittle alpha-case surface layer. Vacuum or inert-atmosphere processing and appropriate cleaning are important to controlling that condition. It also warns about hydrogen pickup during heat treatment and chemical processing. Qualify the actual thermal and cleaning route, including required removal or verification of affected surface layers. Carpenter: heat treatment and contamination

For a loaded component, record sustained temperature, thermal cycles, stress concentrations and surface finish. Validate fatigue and corrosion behavior after the intended machining, cleaning, coating and sterilization sequence where applicable. A room-temperature certificate does not establish a service-temperature limit or a lifetime for an assembled device.

Fabrication and joining

ATI's sheet is explicitly Version 1, 20 February 2012. It describes annealed Grade 23 as difficult to form at room temperature and recommends rigid tooling and suitable cutting-fluid practice for machining. For fusion welding, it stresses protection against oxygen, nitrogen and hydrogen contamination of the molten metal and adjacent heated regions. These are process considerations rather than a universal current, feed, shielding-flow or furnace recipe. ATI: formability, machining and welding

Select tooling, joint preparation, shielding, heat control and inspection through a qualified procedure for the actual form, thickness and application. Control surface contamination and maintain traceability through cutting and machining. Confirm permissible repair, straightening and thermal exposure before applying shop practices developed for a different titanium grade or condition.

Additive manufacture is a separate qualification

Aconity3D's 07/23 Grade 23 sheet explicitly identifies an LPBF process with 30 µm layers and separates as-built from heat-treated properties, including build orientations. It states that results depend on powder, process parameters and surrounding conditions. Such data describe a material-and-process combination; they do not demonstrate compliance of every printed component with a wrought specification. Aconity3D: Ti6Al4V ELI process datasheet

For a printed part, retain powder chemistry and reuse history, machine/parameter set, build orientation, heat treatment or HIP, surface removal and inspection results. Establish relevant defect and surface criteria for the actual geometry, including inaccessible internal features. A nominal density or an acceptable tensile coupon alone does not qualify fatigue-critical features.

Purchase and release record

Retain the exact designation/specification and edition, producer and product form, required chemistry and condition, certificate and heat/lot traceability, sampling and test conditions, fabrication history, and finished-part acceptance criteria. For implants or other regulated uses, establish the applicable device and process requirements separately from raw-material conformity.

The source identities above distinguish F136-26, ATI 2012, AMETEK's printed V3.12.22 code and Aconity 07/23. Carpenter's accessible sheet does not establish a clear revision date. Obtain current controlled documentation for contractual decisions; a website upload date is not a technical edition.

Related reference

Grades, tempers and conditions