CNC Machining TB5 (Ti15V3Cr3Sn3Al): Parameters, Tooling & Surface Finish Tips

Quick Selection Answer: Is TB5 the Right Titanium for Your Part?

TB5 (Ti-15V-3Cr-3Sn-3Al) is a metastable beta titanium alloy, not an alpha-beta grade like Ti-6Al-4V. Choose it when you need a part that can be cold-formed into complex geometry and then aged to high strength. In the solution-treated condition it behaves like austenitic stainless steel for formability, with elongation of 15-25%. After aging at 482-538°C, tensile strength rises to 1000-1450 MPa. If your part is a simple machined block that will never be formed, standard Ti-6Al-4V is usually cheaper and easier to source. If the design demands tight bend radii, cold drawing, or a lower stiffness in service, TB5 earns its cost.

Grade and Standard Designations

TB5 is the Chinese designation for a beta titanium widely known internationally as Ti-15-3-3-3 or Ti-15V-3Cr-3Sn-3Al. Material for sheet, strip, and plate is specified under AMS 4914, and the UNS number is R58153. Because this alloy’s properties depend heavily on heat treatment condition, a drawing that carries only the grade name is incomplete. The condition designation (solution treated, or solution treated plus aged) must be stated on the drawing, otherwise the supplier and the machinist are both guessing.

Approximate equivalents exist in other national systems, but they are not drop-in replacements. A grade that is nominally “beta titanium” may differ in oxygen content, beta transus, or aging response. Treat cross-references as a starting point for discussion, not as interchangeability.

Condition, Supply State, and Chemistry

Most TB5 reaches a machine shop in the solution-treated condition, because that is the state suppliers stock for formability. Solution treatment runs at roughly 815-845°C followed by air cooling or water quenching; unlike some alpha-beta grades, air cooling is sufficient to retain the beta phase in section thicknesses under about 25 mm. Aging then holds the part at 482-538°C for 4-16 hours to precipitate fine alpha phase within the beta matrix.

The table below reflects AMS 4914 composition limits for TB5 sheet, strip, and plate. Substitutional elements control the beta transus; interstitial limits control ductility and aging response, so a mill certificate should list every interstitial.

Typical Mechanical Properties by Condition

The gap between solution-treated and aged TB5 is the single most important fact for a designer. Values below are typical ranges for sheet and plate per AMS 4914; aged figures reflect a representative 510°C, 8-hour cycle. Actual values depend on product form, section size, and the exact aging schedule. Confirm against the applicable specification and the mill certificate for your lot.

Note the ductility trade-off. A solution-treated sheet forms readily at 15-25% elongation, but the same part aged toward 1325 MPa yield strength may retain only 3-6% elongation. Decide which condition the part must survive in service, and machine accordingly. This is also why TB5 draws comparisons with lower-modulus implant materials: in the solution-treated state its modulus is closer to bone, while aging stiffens the lattice. Do not, however, read that as a claim of medical or aerospace qualification for any specific part; suitability depends on the governing standard, certification, and end-use approval, not on the alloy family alone.

CNC Machining TB5: Practical Starting Parameters

The table below is a starting reference only, for solid carbide tooling with TiAlN or AlTiN PVD coatings and high-pressure through-tool coolant. Speeds and feeds shift with machine rigidity, toolholder runout, coolant delivery, tool grade, and the material condition. Treat these as a first trial, then tune to the actual cut, chip, and surface result. No fixed surface roughness or tolerance is implied.

Roughing at 6Al-4V speeds will destroy an edge quickly. Beta titanium has low thermal conductivity, so most heat goes into the tool rather than the chip. Tool selection and coolant strategy matter as much as the numbers: for roughing, uncoated or TiAlN-coated micrograin carbide in an ISO K20-class grade is a common choice, while AlTiN-coated fine-grain carbide or CBN is often used for finishing. Avoid chromium-rich coatings on titanium, and avoid diamond coatings, which degrade rapidly against titanium. For a comparison of how a lower-alloy titanium grade changes these choices, see our TC6 titanium machining notes.

Machining Difficulties to Plan Around

• Work hardening. Solution-treated TB5 work-hardens readily. A dull tool smears the surface and creates a hardened layer, so finishing passes must cut through harder material. Change inserts on a schedule, not on visible failure.
• Chatter and deflection. Aged TB5 cuts with high forces. Long overhangs or weak fixturing produce vibration that both spoils finish and locally work-hardens the surface. Use the shortest practical tool assembly and verify runout.
• Chip control. Solution-treated chips can be continuous and stringy, similar to 300-series stainless. Grooved chipbreaker geometry helps break them. Aged chips are segmented but abrasive.
• Clamping force. In the solution-treated state the yield strength is lower, so excessive clamp pressure can permanently deform the part before cutting starts.
• Heat treatment sequence. If a part needs both heavy removal and tight tolerances, a common approach is to rough in the solution-treated state, age, then finish. Aging produces small dimensional growth, which final machining removes. Confirm this sequence with the heat treater and the drawing requirements. For a grade with a different heat-treatment window, see the TC17 titanium guide.

Applications and Comparisons

TB5 is selected where cold formability plus high aged strength are both required. Typical uses include cold-formed aerospace brackets, ducts, and clips; springs and fasteners; and weight-sensitive motorsport components. When comparing alternatives, compare like for like: state the condition and use the same property. For a near-alpha alternative with different trade-offs, see our TA15 (Ti-6.5Al-2Zr-1Mo-1V) machining notes. Against Ti-6Al-4V, TB5 offers better formability and, in the solution-treated state, a lower elastic modulus, but lower strength if left unaged. Against commercially pure titanium it offers far higher aged strength. None of these comparisons should be read as a compliance statement for a regulated application; that depends on the governing specification and required approvals.

What to Include in Your RFQ

To get an accurate quotation and a manufacturable part, include: the drawing or 3D model with tolerances and surface requirements; the material grade and condition designation (solution treated or aged, with any applicable AMS number); the quantity; required surface finish; any heat treatment or surface treatment specification; and inspection or documentation requirements. With those inputs, machining strategy and feasibility can be assessed properly. Feasibility ultimately depends on material, thickness or geometry, drawing quality, and inspection requirements. Send the details through our custom quote request, and we will review the geometry against TB5’s machining behavior.