TI · titanium
Titanium Ti-6Al-4V (Grade 5)
The alloy the whole titanium reputation comes from. Published index around 20–25% against B1112 = 100%; low thermal conductivity puts the heat in the tool edge, and it work-hardens the moment the cutter rubs.
Quoting this material
- Typical lead time
- 12–20 working days
- Condition
- Annealed (mill annealed); also supplied in STA where higher strength is required
- Achievable finish
- Ra 1.6 µm typical · Ra 0.4 µm best
Machined in-house to your drawing: see the precision CNC machining service and the machine and inspection capability it runs on.
Machinability
Our own 1–10 shop ranking, not a published index: 10 is free-cutting brass C360, 1 is Inconel 718. It ranks how a material behaves on the floor - cycle time, chip control and tool life together. Where a published index exists it is quoted in the note.
The alloy the whole titanium reputation comes from. Published index around 20–25% against B1112 = 100%; low thermal conductivity puts the heat in the tool edge, and it work-hardens the moment the cutter rubs.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Tensile strength | 950 | MPa |
| Yield strength (0.2%) | 880 | MPa |
| Elongation | 14 | % |
| Hardness | 349 | HB |
| Thermal conductivity | 6.7 | W/m·K |
| Modulus of elasticity | 113.8 | GPa |
Hardness, tensile and thermal figures are typical published values for the condition stated. Actual mill certificates govern; send the specification with the drawing and we confirm against the certificate before the material is cut.
Condition
Annealed (mill annealed); also supplied in STA where higher strength is required
Heat treatment
Solution treatment and ageing (STA) raises the strength above the annealed condition, and it is done by the mill or a specialist heat treater, not in a machine shop. Annealing after welding relieves stress without changing the phase structure.
Achievable surface finish
Ra 1.6 µm
Ra 0.4 µm
Surface finish is functional on fatigue parts: a machined scratch in titanium is a crack initiator, and shot peening is often specified to put the surface into compression.
Tooling and cutting parameters
Cutting speed
- 40–80 m/min (carbide)
Feed
- 0.08–0.20 mm/rev turning · 0.05–0.12 mm/tooth milling
Tooling
- Uncoated fine-grain carbide, sharp positive rake, generous corner radius; no honed edges
Coolant
- High-pressure flood, aimed at the edge; through-tool wherever possible
Starting points for carbide on a rigid setup, not a guarantee. The right numbers depend on the machine, the toolholder and the fixturing - ask and we will say what we would actually run.
Typical applications
- Aircraft structural fittings and brackets
- Medical implants (with ELI grades)
- Aerospace engine mount components
- Motorsport and high-performance fasteners
- Subsea and offshore hardware
DFM notes for this grade
- Keep the tool engaged: a dwell or a spring pass work-hardens the surface and the next cut has to get under a skin that is now much harder
- Rigidity is everything - titanium deflects the tool and the part, and chatter in a thin rib will crack the part or the tool before it scrapes the finish
- Sharp corners and rough finishes are fatigue initiators in a part that is usually specified for fatigue: radii and finish are design requirements here, not shop choices
Questions buyers ask
- Why does titanium need such low cutting speeds?
- Because titanium conducts heat away from the cut at roughly a third of steel and a sixteenth of aluminium. All the heat stays in the cutting zone, so the edge reaches softening temperature at a cutting speed where steel would be comfortable. Higher speed does not cut faster - it destroys the tool.
- Can Ti-6Al-4V be heat treated to a higher strength?
- Yes, by solution treatment and ageing, which takes it to roughly 1,100 MPa. It is a mill or specialist operation with a controlled cycle, and it changes the machining behaviour - the STA condition is harder and more notch sensitive than the annealed material we normally cut.
Grades we would quote instead
Ti-6Al-4V ELI
3/10The same alloy as Grade 5 with tighter limits on oxygen, nitrogen and iron.
Grade 4
4/10The strongest of the commercially pure grades - roughly the strength of a mild steel with the corrosion resistance of titanium, and about as hard to cut as a stainless.
Ti-5Al-2.5Sn
3/10An alpha alloy: similar machining behaviour to Ti-6Al-4V with slightly better weldability and lower strength.