TI · 10 grades
Titanium Alloys
Sold on strength-to-weight, paid for in cycle time.
Titanium gives you the strength of a good steel at 57% of the density and with better corrosion resistance than 316 - and charges for it in machining hours, because it conducts heat away from the cut at roughly a third of the rate of steel. Commercially pure grades (2, 4) are for corrosion service; Ti-6Al-4V is the structural workhorse; the ELI variant is the one for medical implants and cryogenic service.
What this family does well, and where it bites
- Ti-6Al-4V: 900+ MPa tensile at 4.43 g/cm³ - steel strength at half the weight
- Low thermal conductivity means the tool edge takes the heat: floods and high pressure coolant
- Notch sensitive - radii and surface finish are functional, not cosmetic
- Certified stock with full traceability is standard for aerospace and medical work
Titanium Alloys grades we machine
Each grade page carries the properties as supplied, what heat treatment does or does not do to it, the achievable surface finish, starting cutting parameters and the DFM notes that matter for that specific grade.
Grade 2
5/10150 HV (~70 HRB) · 345 MPa
The easiest titanium to cut and still awkward by steel standards.
Grade 4
4/10175 HV (~80 HRB) · 550 MPa
The 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-6Al-4V
3/10349 HB (~36 HRC) · 950 MPa
The alloy the whole titanium reputation comes from.
Ti-6Al-4V ELI
3/10~32 HRC · 860–965 MPa
The same alloy as Grade 5 with tighter limits on oxygen, nitrogen and iron.
Ti-5Al-2.5Sn
3/10~320 HB · 790 MPa
An alpha alloy: similar machining behaviour to Ti-6Al-4V with slightly better weldability and lower strength.
Ti-6-2-4-2
2/10~360 HB · 900 MPa
A near-alpha alloy for hot sections: harder and more abrasive than Ti-6Al-4V and correspondingly slower to machine.
Ti-3Al-2.5V
4/10~250 HB · 620 MPa
A leaner alloy than 6Al-4V, developed for tubing: easier to form and weld, and easier to machine while still beating commercially pure grades on strength.
Ti-15-3
3/10~30 HRC annealed · ~42 HRC aged · 1,000–1,200 MPa (aged)
A metastable beta alloy: soft and stringy in the annealed state, and ageing takes it to high strength.
Ti-10-2-3
3/10~36 HRC (aged) · 1,100–1,250 MPa (aged)
A high-strength beta alloy for heavy-section forgings and machined parts.
Grade 7
4/10~160 HV · 345 MPa
Grade 2 chemistry with a small palladium addition.
Questions buyers ask
- Why does titanium cost so much more to machine?
- Three reasons that compound. The material costs 5–10× a comparable steel. The cutting speed is roughly a quarter, so the machine hour rate is charged over a longer cycle. And tooling wears faster, so inserts are consumed several times more quickly. A titanium quote at 3× the aluminium equivalent is normal.
- Does the grade really matter, or is Ti-6Al-4V always the answer?
- For anything structural, Ti-6Al-4V is the default. Grade 2 (commercially pure) is weaker but far more formable and weldable, and it is the right choice for chemical service where strength is not the driver. Grade 23 (Ti-6Al-4V ELI) is the medical one - lower interstitial content, higher toughness, and it is what an implant drawing will specify.