What Grade 4 is
Grade 4 (UNS R50700) is still unalloyed titanium. Nothing is added to it: it reaches 550 MPa by allowing more oxygen (up to 0.40%) and iron (up to 0.50%) than Grade 2 does. Oxygen is an interstitial strengthening element in titanium, and this is the top of the range before the metal loses too much ductility to be useful.
The consequence worth understanding before specifying it: Grade 4 costs formability for strength. Minimum elongation drops to 15% against Grade 2's 20%, so severe cold forming is harder. It remains fully weldable with the same discipline as Grade 2.
Chemical composition
| Element | Limit |
|---|---|
| Nitrogen, N | 0.05 |
| Carbon, C | 0.08 |
| Hydrogen, H | 0.015 |
| Iron, Fe | 0.50 |
| Oxygen, O | 0.40 |
| Titanium, Ti | Balance |
Composition limits and mechanical values below are the published requirements of the referenced ASTM specification. They state what the standard requires — they are not the measured result of any particular heat or lot, and they are not a guarantee of what a given order will return.
Mechanical properties
| Property | Minimum value |
|---|---|
| Tensile strength | 550 MPa (80 ksi) |
| Yield strength, 0.2% offset | 483 MPa (70 ksi) |
| Elongation in 2 in / 50 mm | 15% |
| Reduction of area (bar, ASTM B348) | 25% |
| Typical density | 4.51 g/cm³ (reference value) |
Values are annealed-condition minimums. Cold-worked material reaches higher strength with lower ductility; cold-worked supply is quoted to the specific requirement.
Grade 4 in dental CAD/CAM
The single largest use of Grade 4 that buyers enquire about is the milling disc — the blank stock that dental laboratories machine into implant superstructures, abutments and frameworks on a CAD/CAM mill. Grade 4 is chosen there because it delivers high strength from an unalloyed chemistry: no vanadium, and a surface that behaves predictably in the oral environment.
Two boundaries are worth stating plainly. First, this page describes the material standard and how the grade is used in the sector — it is not a medical-device claim. Second, whether we can supply disc stock in a given diameter and thickness, and to which certificate, is confirmed on inquiry rather than asserted here.
Choosing between Grade 2, Grade 4 and Grade 23 when strength matters
| If the requirement is… | Usually specified | Why |
|---|---|---|
| Corrosion duty plus moderate loads, easiest forming | Grade 2 | Highest ductility of the three and usually the lowest cost level |
| More strength, still unalloyed, no vanadium | Grade 4 | 550 MPa from interstitial strengthening; the dental-milling standard choice |
| Highest strength with toughness and low interstitials | Grade 23 (ELI) | Alloyed with aluminium and vanadium, tighter interstitials, and a different cost level |
A detailed side-by-side of the two extremes is given in Grade 2 vs Grade 5, and Grade 23 with its interstitial control is covered on the Grade 23 page.
Forms we quote in Grade 4
- Plate and sheet — the most commonly enquired Grade 4 form; see plate & sheet.
- Machined parts — components produced to drawing in Grade 4; see machined parts.
- Disc and block stock — supply availability, size range and certificate type are confirmed on inquiry.
Availability, size range and lead time for a specific grade and form are confirmed in the quotation — please contact us for confirmation.
Need Grade 4 plate or disc stock? Send diameter, thickness, standard and quantity and we will confirm what can be quoted.
WhatsAppSend your specificationRequest Grade 4 titanium
State the form, dimensions, quantity and the standard your drawing references. If you are deciding between Grade 2, Grade 4 and Grade 23, describe the load case and the environment and we will give a view.
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