The Bench · N° 52

Grade 2 and Grade 5 titanium solve different problems

Grade 2 is commercially pure, corrosion-resistant and comparatively formable. Grade 5 adds aluminium and vanadium for much greater strength, with a different price and manufacturing burden.

Hen & Mills Editorial · 5 min read · 18 October 2026

Grade 2 and Grade 5 titanium are not quality levels in a simple ladder. Grade 2 is commercially pure titanium chosen for corrosion resistance and workable ductility, while Grade 5 is a titanium alloy chosen when substantially higher strength is worth more difficult processing.

Two recipes under one familiar colour

ASTM identifies Grade 2 as unalloyed titanium and Grade 5 as an alloy containing about six per cent aluminium and four per cent vanadium, commonly written Ti-6Al-4V. Both are light compared with steel and both form a protective oxide film that gives titanium its celebrated corrosion resistance. Their similar grey appearance hides a large mechanical difference.

Daido Steel's published minimum figures make the contrast plain. Its annealed ASTM Grade 2 data lists yield strength of at least 275 MPa and tensile strength of at least 345 MPa. Grade 5 is listed at 828 MPa yield and 895 MPa tensile strength. Exact properties depend on product form and heat treatment, but the scale of the gap explains why the alloy appears in demanding structural components.

Strength is not the same as surface hardness

A stronger alloy can carry more load before permanently deforming, yet a watch owner mostly notices what happens in the first few micrometres of the surface. Untreated titanium is prone to visible scuffs and galling. Its oxide and the way the underlying metal deforms can make marks look dramatic, even when the case remains structurally untroubled.

Watch brands address this with hardening treatments and coatings. Citizen describes untreated titanium as soft and difficult to process, then uses Duratect surface technologies in its Super Titanium cases. The surface treatment can dominate scratch behaviour, so comparing a coated Grade 2 case with an untreated Grade 5 case by grade alone tells little about which will look newer after a year.

Why Grade 2 remains useful

Commercially pure Grade 2 offers excellent resistance to many corrosive environments, good formability and more elongation before failure than the stronger alloy. Those traits suit formed parts and cases where extreme structural strength is unnecessary. A watch case is not an aircraft landing component. Its wall thickness, geometry and case-back system can provide ample stiffness with either material.

Grade 2 also gives designers the characteristic darker, softer grey associated with titanium, depending on finish. It can be blasted for a muted technical surface or brushed to show directional grain. Machining still demands suitable tools and control because titanium conducts heat poorly and has a tendency to adhere at the cutting edge.

What Grade 5 buys

Grade 5 allows higher strength at similar low density. A designer may use that margin for thinner sections, sharper load-bearing details or greater resistance to deformation. The alloy can also take refined alternating finishes when the manufacturer has mastered the cutting and polishing process, which helps explain its use in expensive cases with bright bevels.

It is not automatically lighter on the wrist. Density is similar enough that case dimensions, crystal, movement, bracelet and clasp determine the finished mass. If two manufacturers use the same external shape and wall thickness, the material choice alone will not create a dramatic weight gap between the grades.

Machining shapes the price

Titanium's low thermal conductivity leaves heat near the tool. Its chemical reactivity encourages pickup, and springback complicates forming. Grade 5's higher strength adds cutting load. Tool geometry, speed, coolant and workholding all need attention, particularly where a case combines deep pockets, thin walls and crisp decorative planes.

The finished component may require separate blasting, brushing and polishing operations, with strict control at their borders. A simple matte case can be less expensive to produce than an intricate mixed-finish one even if both use the same alloy. “Grade 5” does not contain a labour estimate.

Skin comfort needs careful wording

Titanium is widely used where corrosion resistance and biocompatibility matter, and many wearers find it comfortable because it is light and warms quickly against the wrist. Yet a complete watch includes pins, screws, a clasp and possibly coatings or coloured treatments. A titanium case label does not guarantee that every touching component has the same composition.

Allergy claims should therefore belong to the exact product and its tested materials. Grade numbers describe alloy chemistry and mechanical requirements. They do not certify an assembled watch for every wearer.

The finish changes the personality

Bead blasting scatters light and can make titanium look dark and uniform, although contact marks may burnish the surface. Brushing gives scratches a visual direction and can make later wear less conspicuous. Polished Grade 5 can look surprisingly bright, but a mirror area will advertise fine marks just as polished steel does.

Surface hardening changes the equation again. Some treatments diffuse elements into the surface, while others deposit a hard coating. Their colour, depth, adhesion and repair options differ. If a treated surface is polished during service, the treatment may be altered or removed. Owners should ask about the entire finish system before assuming a local refinisher can restore it conventionally.

Reading a titanium specification

First identify whether the brand states commercially pure titanium, Grade 2, Grade 5 or only “titanium”. Then look for a named surface treatment and a hardness claim with a test method. Case construction and finish deserve equal attention. A well-executed Grade 2 case can be more suitable and more attractive than a poorly finished Grade 5 one.

The grade becomes meaningful when it is connected to a design decision. Higher strength is valuable if sections are thin or loads are concentrated. Formability and corrosion behaviour may matter more in another component. Surface durability comes from what was done to the surface, not merely from the bulk alloy beneath it.

Different answers, neither universal

Grade 2 is not the budget imitation of Grade 5, and Grade 5 is not an automatic upgrade for every watch. One favours commercially pure titanium's workability and corrosion performance. The other trades alloying and manufacturing effort for far higher strength.

The honest question is not which number wins. It is what the case designer needed the material to do, how the surface was treated and whether the finished geometry takes advantage of the choice.