Titanium alloy grade choice is set by four hard selection gates: required strength-to-density ratio, service temperature window, corrosion regime, and form availability (bar, plate, wire, fasteners). Across the 2026 supply base, CP-Grade 2 commercially-pure titanium, Ti-6Al-4V (Grade 5), Ti-6Al-4V ELI (Grade 23), and β-rich TB2 cover roughly 80% of OEM inquiries [S1].
Raw material spread between grades is wide: CP-Grade 2 sheet trades at one baseline, Ti-6Al-4V bar at roughly 3-5x, and β alloys such as TB2 at 5-10x that same baseline per kg, driven by vanadium, molybdenum, and chromium master-alloy cost and by tighter hot-working windows [S1]. Buyers who skip the grade gate end up overpaying 2-4x for capability they will not use, or under-spec'ing a part that fails in service.
Grade Family Map: CP, α+β, β
CP titanium (Grades 1-4) is unalloyed with oxygen as the primary strength lever; Grade 2 is the workhorse for chemical processing pipe, plate heat exchangers, and marine hardware, typically specified to ASTM B265 / B348 [S1].
Ti-6Al-4V (Grade 5) is the dominant α+β alloy: 6% aluminium, 4% vanadium, nominal tensile yield ~880 MPa, density 4.43 g/cm³, and a useful service window from cryogenic up to roughly 315-330 °C [S1][S2]. It covers aerospace structural fittings, medical implants (as ELI variant), and high-performance titanium alloy fasteners such as 45° titanium elbows and wheel-hub bolts listed in the 2026 supplier catalogue [S1].
β and near-β alloys — TB2, Ti-10V-2Fe-3Al, Ti-15V-3Cr-3Al-3Sn — push tensile strength above 1100 MPa after ageing, with deep hardenability sections over 100 mm, but trade away weldability and high-temperature creep [S3]. TB2 is documented for electron-beam and TIG welded joints where the heat-affected zone microstructure and micro-hardness must be qualified; the β family generally tops out near 300 °C in continuous service [S3].
Selection Criteria: 4 Hard Gates
Gate 1 — Mechanical demand. If allowable tensile yield under 350 MPa suffices, CP-Grade 2 saves 60-75% on raw bar cost versus Ti-6Al-4V [S1]. If the design needs >800 MPa yield at <4.5 g/cm³ density, the α+β family (Grade 5 / Grade 23 ELI) is the default; β alloys enter only when section thickness forces deep hardenability or when ageing response is required.
Gate 2 — Temperature envelope. CP and Ti-6Al-4V are limited to roughly 330 °C continuous; above that, creep in the α phase accelerates. For service approaching 425-540 °C, near-α alloys (Ti-6Al-2Sn-4Zr-2Mo, IMI 685) and α+β alloys with higher Mo/W content are specified; β alloys are not used in this hot band [S2].
Gate 3 — Corrosion regime. Titanium is passive in oxidising media (chlorinated water, nitric acid, wet chlorine) but vulnerable to reducing acids (HCl, H₂SO₄) and to crevice corrosion in hot halide brines above ~70 °C. CP-Grade 2 performs as well as Ti-6Al-4V in most oxidising service, so the upgrade to Grade 5 is rarely justified on corrosion grounds alone [S1].
Gate 4 — Form, machining, weld. CP grades cold-form, deep-draw, and weld with no special procedure. Ti-6Al-4V welds with inert-gas shielding (AWS A5.16 filler) but loses ~10-15% joint efficiency in the as-welded condition; β-rich TB2 requires post-weld solution-and-age treatment to recover properties [S1][S3]. Machining cost is the hidden line item: titanium's low thermal conductivity forces low cutting speeds, and Ti-6Al-4V is roughly 3-4x more expensive to machine than alloy steel of equivalent hardness.
Comparative Table: CP-Grade 2 vs Ti-6Al-4V vs TB2
Lining the three dominant options against four decision criteria, the spread is sharp: [S1]
Mechanical — CP-Grade 2: yield ~275-450 MPa, UTS ~345-550 MPa, elongation >20%. Ti-6Al-4V: yield ~880 MPa, UTS ~895-930 MPa, elongation ~10-14%. TB2 (β, aged): UTS >1100 MPa, elongation ~6-10% [S1][S3].
Temperature — CP-Grade 2: continuous to ~315 °C. Ti-6Al-4V: continuous to ~315-330 °C. TB2: limited to ~300 °C, with rapid creep above [S2][S3].
Corrosion — All three share the passive TiO₂ layer and behave similarly in oxidising media; CP-Grade 2 is generally sufficient where Ti-6Al-4V is selected for strength, not corrosion [S1].
Cost & form — CP-Grade 2 is the cheapest and most available in plate, sheet, bar, and wire coil. Ti-6Al-4V carries a 3-5x premium and is widely stocked in bar, billet, plate, and fastener forms including wheel-hub bolts and pipe fittings [S1]. TB2 is a specialty order, typically 5-10x CP-Grade 2 per kg, with limited distributor stock.
Standards, Sourcing, and Welding Filler
Mill form standards for plate/sheet (ASTM B265), bar/billet (ASTM B348), pipe (ASTM B861/B862), and fittings (ASTM B363) govern dimensional and chemical limits; for aerospace, AMS 4911 (Ti-6Al-4V sheet) and AMS 4928 (Ti-6Al-4V bar) are the reference specifications. Welding consumable follows AWS A5.16 — titanium and titanium-alloy welding wire and rod — with matching grade filler (ERTi-2 for CP, ERTi-5 for Ti-6Al-4V) [S1].
For buyers comparing 2026 supply, the pattern in published mill catalogues is consistent: a Chinese mill offers CP-Grade 1/2/4 sheet and plate, Ti-6Al-4V bar and billet, and β-alloy TB2 bar on mill order, plus secondary products such as 45° titanium elbows, wheel-hub bolts, and titanium pipe fittings in Ti-6Al-4V [S1]. Peer-relation context for buyers balancing aluminum alloy versus titanium for low-density structural parts is covered in our carbon steel vs cast iron spec domain guide and our carbon steel buying guide 2026.
Failure Modes and Mis-Spec Traps
Mis-spec 1 — Specifying Ti-6Al-4V where CP-Grade 2 suffices. Common in chemical-plant pipe where the designer defaults to "stronger = safer"; cost penalty is 3-5x per kg with no corrosion benefit in oxidising service [S1].
Mis-spec 2 — Specifying β-rich TB2 for welded assemblies expecting as-welded strength. The HAZ softens markedly; post-weld solution treatment and ageing are mandatory to recover UTS above 1100 MPa [S3].
Passive-layer breakdown is rapid and is not recovered by upgrading to a higher alloy content [S1].
Mis-spec 4 — Ignoring machining cost. Switching a part from 17-4PH stainless / alloy steel to Ti-6Al-4V cuts weight 40% but can raise total part cost 2-3x once cycle time, tool wear, and fixturing are counted. The right gate to optimise is mass-critical, not strength-critical, applications.
Who Titanium Is For (and Who It Is Not)
Specifying titanium makes sense for: aerospace primary and secondary structure (Ti-6Al-4V, Ti-6Al-4V ELI), medical implants (Grade 23 ELI, Grade 1/2 for instruments), chemical-process heat exchangers and anodes (CP-Grade 2), marine fasteners and propeller shafts (Ti-6Al-4V, Grade 2), and high-performance automotive connecting rods and wheel-hub bolts where mass saving is paid for [S1].
Titanium is the wrong call for: hot-service above 540 °C (use nickel superalloys — see nickel alloy), reducing-acid service without lined construction, cost-sensitive structural frames where carbon steel or aluminum alloy meet the load case, and any application where the buyer cannot absorb a 3-10x raw-material premium for the life of the part.
For buyers weighing titanium against competing alloy families on a 2026 RFQ, our related selection reads on tank container selection criteria and mesh belt conveyor buying guide 2026 put the same gate logic against different equipment classes.
Trackable signals for the next 90 days: ASTM B348 revision activity on Ti-6Al-4V ELI interstitial limits, AWS A5.16 filler-grade additions for β-alloy wire, and mill-order lead times for TB2 bar quoted against CP-Grade 2 plate stock. A spread of TB2 lead time above 16 weeks versus CP-Grade 2 below 6 weeks is the clearest read on β-alloy supply tightness in mid-2026 [S1][S3].