Titanium

A light metal (4.4–4.5 g/cm³) protected by a tough oxide film. Unalloyed grades 1–4 differ in oxygen and strength; Ti-6Al-4V (Grade 5) is the high-strength alloy.

Where it is used

Seawater piping, heat exchangers and chemical plant
Aircraft structures, engine parts and fasteners
Medical implants and marine hardware

Strengths

Strength comparable to steel at about 57 % of its weight
Outstanding resistance to seawater and chlorides
Keeps its strength up to about 350 °C (Grade 5)

Limitations

Expensive and hard to machine
About half the stiffness of steel
Welding needs full inert-gas shielding

Typical values: Ti-6Al-4V (Grade 5)

ASTM B265

0.2 % proof strength Rp0.2: ≥ 828 MPa; guaranteed minimum · annealed, sheet and plate 0.025–1.000 in; also ASTM B348 bars < 3 in; 1
Tensile strength Rm: ≥ 895 MPa; guaranteed minimum · annealed, sheet and plate 0.025–1.000 in; also ASTM B348 bars < 3 in; 1
Elongation after fracture A: ≥ 10 %; guaranteed minimum · annealed; 1
Density ρ: 4 420 kg/m³; nominal; 1
Modulus of elasticity E: 107 000–122 000 MPa; guaranteed range; 1

What engineers ask about titanium

How light is it, and how stiff?

Ti-6Al-4V weighs 4.42 g/cm³ with E 107–122 GPa; unalloyed Grade 2 weighs 4.51 g/cm³ with E 105–120 GPa. That is about 57 % of the weight of steel and about half its stiffness.

Density and modulus on each grade

1 Sources

1
Titanium Metals Corporation (TIMET) — TIMETAL 6-4, 6-4 ELI & 6-4-.1Ru, data sheet · Table 2
AuthoritativeProducerRead in full · 2 Nov 2026
2
Titanium Metals Corporation (TIMET) — TIMETAL 50A, commercially pure titanium (ASTM Grade 2), data sheet · Table 2
AuthoritativeProducerRead in full · 2 Nov 2026

Where is it used for corrosion resistance?

Grade 2 is used for seawater piping, reactor vessels and heat exchangers, with excellent resistance to erosion and corrosion by seawater and marine atmospheres; Ti-6Al-4V is highly resistant to general corrosion in seawater.

1 Sources

1
Titanium Metals Corporation (TIMET) — TIMETAL 50A, commercially pure titanium (ASTM Grade 2), data sheet · Introduction
AuthoritativeProducerRead in full · 2 Nov 2026
2
Titanium Metals Corporation (TIMET) — TIMETAL 6-4, 6-4 ELI & 6-4-.1Ru, data sheet · Introduction
AuthoritativeProducerRead in full · 2 Nov 2026

Titanium grades

Unalloyed titanium and Ti-6Al-4V: high strength for their weight and resistance to seawater.

Standard fromAnywhere

ASTM

Unalloyed (commercially pure) titanium

Grades 1–4 differ by oxygen and iron content: more oxygen, more strength, less formability.

Grade	Standard	0.2 % proof strength	Tensile strength	Evidence
Titanium Grade 2 The workhorse unalloyed titanium: guaranteed Rp0.2 275 MPa, 4.51 g/cm³, outstanding resistance to seawater and chlorides.	ASTM B265	≥ 275 MPa1	390–540 MPa—	Single source 14 Trade sources only 2 Disagreements explained 2

Alpha-beta titanium alloys

Ti-6Al-4V and relatives: heat-treatable, high strength for their weight.

Grade	Standard	0.2 % proof strength	Tensile strength	Evidence
Ti-6Al-4V (Grade 5) The most used titanium alloy: annealed Rm 895 MPa, Rp0.2 828 MPa at 4.4 g/cm³ — steel-like strength at 56 % of its weight.	ASTM B265	≥ 828 MPa1	≥ 895 MPa1	Single source 19 Disagreements explained 3

Planned groups

Grades 1, 3 and 4; Ti-6Al-4V ELI (Grade 23); Grade 7 and 12

Standards for titanium

ASTM B265

All standards for titanium