Guides/Comparisons
Titanium vs steel
titanium-vs-steelTitanium and Steel at a glance
This page compares Titanium and Steel using only values that carry a source, a test condition and an evidence level. Ranges run across temper, heat treatment and product form, measured at room temperature where the source says so.
- Yield strength: the ranges overlap (Titanium 138 to 1,282 MPa; Steel 170 to 1,330 MPa).
- Tensile strength: the ranges overlap (Titanium 240 to 1,300 MPa; Steel 310 to 1,600 MPa).
- Density: the ranges overlap (Titanium 3.8 to 8.3 g/cm³; Steel 7.67 to 8.03 g/cm³).
- Young's modulus: the ranges overlap (Titanium 82 to 207 GPa; Steel 190 to 210 GPa).
- Thermal conductivity: Steel is higher (Titanium 0.71 to 22 W/(m·K); Steel 25 to 93 W/(m·K)), about 5.2 times the midpoint of Titanium.
- Melting point: Titanium is higher (Titanium 1,604 to 1,670 °C; Steel 1,432 to 1,526 °C), about 1.1 times the midpoint of Steel.
- Thermal expansion: the ranges overlap (Titanium 8.6 to 9.7 ppm/K; Steel 3.44 to 14.6 ppm/K).
- Yield strength for each unit of density (calculated from each grade's midpoint values): Titanium 49.7 to 229 MPa per g/cm³; Steel 32.6 to 115 MPa per g/cm³.
"Higher" means the whole range is higher, not just one value. Where a value is a specified minimum, the table says "at least".
Side by side
| Property | Titanium | Steel |
|---|---|---|
| Yield strength | 138 to 1,282 MPa | 170 to 1,330 MPa |
| Tensile strength | 240 to 1,300 MPa | 310 to 1,600 MPa |
| Density | 3.8 to 8.3 g/cm³ | 7.67 to 8.03 g/cm³ |
| Young's modulus | 82 to 207 GPa | 190 to 210 GPa |
| Thermal conductivity | 0.71 to 22 W/(m·K) | 25 to 93 W/(m·K) |
| Melting point | 1,604 to 1,670 °C | 1,432 to 1,526 °C |
| Service temperature | 288 to 540 °C | no data |
| Thermal expansion | 8.6 to 9.7 ppm/K | 3.44 to 14.6 ppm/K |
| Yield strength per densitycalculated | 49.7 to 229 MPa per g/cm³ | 32.6 to 115 MPa per g/cm³ |
When to use which
| Material | Best for | Weakest at |
|---|---|---|
| Commercially pure titanium, Grade 2 (UNS R50400) | Seawater, brine and chloride service where corrosion resistance and formability matter more than strength (Alleima and Smiths datasheets) | Strength: 345 MPa minimum tensile, well below Ti-6Al-4V (see the Ti-6Al-4V profile). Crevice attack in hot seawater from about 80 °C (Pang and Blackwood 2016) |
| Ti-6Al-4V | Strength-to-weight structures that must stay strong up to about 400 degC, such as aerospace forgings and bars (the datasheet gives 4.43 g/cm3 density and 830 to 950 MPa yield) | Low thermal conductivity (6.7 W/(m K) at 20 degC), and lower ductility once it is solution-treated and aged (6 to 10 % elongation) |
| Titanium alloy Ti-6Al-4V ELI (Grade 23) | Cold-service hardware and medical implants where toughness and low interstitial content matter (Carpenter; UPMET; Titanium Industries). | Thermal conduction: 6.6 W/(m K) at 20 degC is low for a metal (UPMET). The sources read give no room-temperature fracture toughness for commercial bar. |
| Titanium Grade 9, Ti-3Al-2.5V (UNS R56320) | Seamless hydraulic and fluid tube, corrosion-resistant pipe and sporting frames, where more strength than commercially pure titanium is needed with more formability than Grade 5 (Smiths datasheets, Bibus) | Strength below Grade 5: 620 MPa minimum tensile when annealed, against 895 MPa for Grade 5 (ASTM B265). No thermal, cryogenic or space data for this grade were read in this run. |
| TiAl | Light rotating parts that run hot, such as low-pressure turbine blades in GE engines, where a density near 3.8 g/cm3 and a stiffness of 168 GPa matter more than ductility | Room-temperature ductility, since cast Ti-48-2-2 elongates only 1.70 % at 23 degC and impact can crack thin sections |
| Beta 3 | Parts that are cold formed in the solution-treated state and then aged to high strength, such as TIMETAL 15-3 strip (1000 MPa minimum tensile after 8 h at 538 degC) | Ductility after ageing (TIMETAL 15-3 strip falls to 5 to 7 % elongation), and the Beta 3 strength data are missing from the sources read |
| Commercially pure titanium with palladium, Grade 11 (UNS R52250) | Chloride and reducing-acid chemical plant equipment, and desalination or marine service, where crevice corrosion resistance matters more than strength (S+D Metals and Elgiloy datasheets) | Strength: 240 MPa minimum tensile, below the 345 MPa minimum of Grade 2 (ASTM B265). No Grade 11 crevice-corrosion test temperature was found in the sources read for this profile |
| Commercially pure titanium, Grade 3 (UNS R50550) | Formed and welded parts that need more strength than Grade 2 while keeping weldability and corrosion resistance in oxidising, neutral and mildly reducing media (Smiths) | Strength: 450 MPa minimum tensile, well below Ti-6Al-4V (see the Ti-6Al-4V profile). Oxygen limit of 0.35 %, the highest of CP grades 1 to 3 in ASTM B265 Table 2 |
| Commercially pure titanium, Grade 7 | Chemical processing and hot chloride or acid service where crevice corrosion is the main concern and Grade 2 is not enough (ATI corrosion data sheet; Elgiloy datasheet) | Strength: 345 MPa minimum tensile, the same as Grade 2 and well below Ti-6Al-4V. Its crevice limit depends on pH and temperature, and no Grade 7 test at pH 1 or below was read in this run |
| Minor titanium alloys, Ti-Mo, Ti-V, Ti-Fe, Ti-Si | Ti-10V-2Fe-3Al for forged, heat-treated structural parts that must hold about 1000 N/mm2 tensile strength at room temperature and about 900 N/mm2 at 315 degC | Ti-Mo binaries lose ductility when aged or cast (Ti-15.05Mo falls to 6.95 % elongation after solution treatment), and Ti-Ga, Ti-Si and Ti-V have no alloy-level property value in the sources read |
| A36 structural carbon steel | Welded and bolted structural frames, girders and shapes that will be painted or galvanized | Rusts outdoors and corrodes first when it touches copper or tin in a wet electrolyte; minimum strength falls above 650 °F (343 °C) |
| Carbon steel 1018 | Machined shafts, pins and gears, and cost-sensitive structural parts that are coated against rust | Rust in moist air and salt unless it is coated, and strength that depends on whether the bar was cold drawn or hot rolled |
| Carbon steel 1045 | Forged or machined axles, shafts, gears and machine parts that need more strength than low-carbon steel, and that are coated against rust | Rust in moist air and salt unless it is coated, and strength that depends on whether the bar was cold drawn, hot rolled, normalised or annealed |
| Carbon steel 1215 | Screw-machine parts such as bushings, inserts, pins, studs and couplings, where machining speed and surface finish matter more than weldability (Alro; Titanium Industries) | Welding and fatigue. Alro says it is difficult to weld, and Titanium Industries says it fails in parts under severe fatigue stress |
| Alloy steel AISI 4130 | Aircraft and motorsport tube, sheet and bar, and oil and gas parts, where weldability and strength after heat treatment both matter | Hydrogen gas and salt solutions: in one laboratory study the threshold stress intensity fell from 88 to 32 MPa√m as hydrogen pressure rose from 21 to 69 MPa, and salt solution cut corrosion-fatigue life |
| Alloy steel AISI 4140 | Machine parts and structures in medium and large sections that need high strength and toughness after quenching and tempering | Hydrogen gas, which cut notched strength by about 60 percent in one room-temperature study, and dilute sulfuric acid, which corroded it at 176.87 mpy |
| Carbon steel 1010 | Formed, drawn and welded parts, and light structural parts, where cost and ductility matter | Rust in moist air and salt unless it is coated, and strength that depends on the processing condition |
| Carbon steel 1070 | Springs, shafts and hand tools that are heat treated and kept dry or coated (tensile strength 640 to 700 MPa in the supplier range) | Corrosion, which is poor without a coating, brittleness once fully hardened, and poor weldability |
| Alloy steel AISI 4340 | Large sections that need high tensile strength and toughness after quenching and tempering, such as aircraft landing gear, gears and shafts (voestalpine, Saky Steel). | Toughness at the highest strength levels: the minimum Charpy impact energy falls from 42 J at condition U to 9 J at condition Z (voestalpine). No corrosion data were read for this grade. |
Where each is used
| Material | Use |
|---|---|
| Commercially pure titanium, Grade 2 (UNS R50400) | Seawater-cooled heat exchanger and condenser tubing |
| Commercially pure titanium, Grade 2 (UNS R50400) | Desalination pipe and reverse-osmosis pressure vessels |
| Commercially pure titanium, Grade 2 (UNS R50400) | Aerospace hydraulic tubing (AMS 4943 annealed; AMS 4944 and 4945 cold worked and stress relieved) |
| Ti-6Al-4V | Aerospace forging and bar (example of an AMS 4928 bar forging) |
| Ti-6Al-4V | Aircraft and spacecraft structural parts made to AMS 4928 and AMS 4911 |
| A36 structural carbon steel | General construction and structural framing |
| A36 structural carbon steel | Girders, structural shapes and angle iron |
| A36 structural carbon steel | Bolted and welded structural joints |
| Carbon steel 1018 | Shafts, pins and gears |
| Carbon steel 1018 | Low-stress structural components |