AISI 316L and Ti Grade 2 are frequently weighed up as alternatives for the same equipment in the chemical and marine industries. Both are corrosion resistant and both weld easily. The difference is in which type of corrosion they withstand.
Chloride: the limit of 316L
The protective layer of 316L is chromium oxide, and that layer can be pierced locally by chloride ions. The result is pitting and crevice corrosion. As temperature rises that limit falls quickly; in hot seawater 316L is not a safe choice.
The protective layer of titanium is titanium dioxide. That layer is extremely stable against chlorides; Ti Grade 2 lasts practically indefinitely in seawater and does not pit. Stress corrosion cracking is not seen in titanium either.
On the mechanical side 316L is ahead, but the difference is not as large as supposed: according to our datasheets the yield strength of 316L is 170 MPa against ≥275 N/mm² for Ti Grade 2 — that is, titanium actually gives the higher yield strength. In tensile strength 316L (485 MPa) is ahead of titanium (≥345 N/mm²).
The weight difference is decisive: titanium 4.51 g/cm³, 316L 8.00 g/cm³. Titanium is half the weight.
Titanium is ahead in thermal conductivity as well (20 against 16.3 W/m·K) — in heat exchanger applications that translates directly into efficiency. In exchange, the cost of titanium is markedly higher and it is harder to machine.
Comparison in numbers
| PROPERTY | AISI 316L | Ti Grade 2 |
|---|---|---|
| Material class | Austenitic stainless steel | Commercially pure titanium |
| Main elements | 16–18% Cr · 10–14% Ni · 2–3% Mo | Ti (balance) |
| Carbon (C) | max 0.03% | ≤ 0.08% |
| Tensile strength | 485 MPa | ≥ 345 N/mm² |
| Yield strength Rp0.2 | 170 MPa | ≥ 275 N/mm² |
| Elongation | 40% | ≥ 20% |
| Hardness | max 217 HB | ≤ 150 HB |
| Density | 8.00 g/cm³ | 4.51 g/cm³ |
| Modulus of elasticity | 193 GPa | 105 kN/mm² |
| Thermal conductivity | 16.3 W/m·K | 20 W/m·K |
| Chloride / seawater resistance | Limited (pitting risk) | Very high |
| Stress corrosion cracking | Risk in hot chlorides | Not seen in practice |
| UNS | S31603 | R50400 |
| AMS | 5653 · 5507 | 4902 · 4941 · 4942 · 4951 |
Values are taken from our product datasheets; section thickness and the applied heat treatment regime change the result.
Which one, and when?
AISI 316L is sufficient — food and pharmaceutical pipework, indoor process equipment, water lines with a low chloride load, welded tanks, general industrial use. Its cost is far below that of titanium and it is easy to find in every form.
Ti Grade 2 is required — seawater heat exchangers, desalination plants, chlor-alkali equipment, offshore pipelines, coastal facilities, corrosive environments where weight matters. Above the temperature and chloride level at which 316L begins to pit, it is the only reasonable solution.
An economic note: the initial cost of titanium is high, but in an environment where 316L has to be replaced every few years the total cost of ownership turns in titanium’s favour.
Intermediate solutions
For budget and performance needs between 316L and titanium, see our AISI 904L and duplex AISI 318 comparisons.
Technical datasheets
AISI 316L — chemical composition, mechanical values, standard equivalents
Ti Grade 2 — chemical composition, mechanical values, standard equivalents
Both grades are supplied to order in round bar, flat bar, plate, sheet, pipe and forged forms. Contact us for a quotation.