SS 316 / 316L – Chemical Composition, Equivalents & Products
SS 316 is an austenitic stainless steel containing 16–18% chromium, 10–14% nickel and 2–3% molybdenum. The molybdenum gives it markedly better resistance than 304 to pitting and crevice corrosion in chloride environments and to many acids, which makes 316 the standard grade for marine, chemical, pharmaceutical and food processing equipment. SS 316L is the low-carbon version used for welded construction, and most material is dual certified 316/316L.
Giriraj Impex supplies SS 316 and 316L in every product form – we manufacture flanges, fittings, bars and fasteners, and stock and supply pipes, tubes, plates and sheets. This page gives the grade's composition, properties and equivalent designations.
Chemical composition
The limits for plate and sheet (ASTM A240) and for pipe (ASTM A312) are shown below; they differ slightly between product standards.
| Grade | UNS | C | Mn | P | S | Si | Cr | Ni | Mo | N |
|---|---|---|---|---|---|---|---|---|---|---|
| 304 | S30400 | 0.07 | 2.00 | 0.045 | 0.030 | 0.75 | 17.5–19.5 | 8.0–10.5 | – | 0.10 |
| 304L | S30403 | 0.030 | 2.00 | 0.045 | 0.030 | 0.75 | 17.5–19.5 | 8.0–12.0 | – | 0.10 |
| 316 | S31600 | 0.08 | 2.00 | 0.045 | 0.030 | 0.75 | 16.0–18.0 | 10.0–14.0 | 2.00–3.00 | 0.10 |
| 316L | S31603 | 0.030 | 2.00 | 0.045 | 0.030 | 0.75 | 16.0–18.0 | 10.0–14.0 | 2.00–3.00 | 0.10 |
Other elements and footnotes as given in the standard.
| Grade | UNS | C | Mn | P | S | Si | Cr | Ni | Mo |
|---|---|---|---|---|---|---|---|---|---|
| TP304 | S30400 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0–20.0 | 8.0–11.0 | – |
| TP304L | S30403 | 0.035 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0–20.0 | 8.0–13.0 | – |
| TP316 | S31600 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0–18.0 | 10.0–14.0 | 2.00–3.00 |
| TP316L | S31603 | 0.035 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0–18.0 | 10.0–14.0 | 2.00–3.00 |
Other elements and footnotes as given in the standard. Dual-certified material meets both grades.
Mechanical properties
| Grade | Tensile strength min, MPa (ksi) | Yield strength min, MPa (ksi) | Elongation in 50 mm min, % | Hardness max, HBW / HRB |
|---|---|---|---|---|
| 304 | 515 (75) | 205 (30) | 40 | 201 / 92 |
| 304L | 485 (70) | 170 (25) | 40 | 201 / 92 |
| 316 | 515 (75) | 205 (30) | 40 | 217 / 95 |
| 316L | 485 (70) | 170 (25) | 40 | 217 / 95 |
Values for annealed material.
Dual-certified 316/316L meets the 0.030% maximum carbon of 316L and the minimum strength of 316.
Equivalent grades
| Grade | UNS | EN number | EN name | JIS | BS |
|---|---|---|---|---|---|
| 304 | S30400 | 1.4301 | X5CrNi18-10 | SUS304 | 304S31 |
| 304L | S30403 | 1.4307 | X2CrNi18-9 | SUS304L | 304S11 |
| 316 | S31600 | 1.4401 | X5CrNiMo17-12-2 | SUS316 | 316S31 |
| 316L | S31603 | 1.4404 | X2CrNiMo17-12-2 | SUS316L | 316S11 |
Equivalent grades are similar but not identical; composition and property limits differ between standards. Order to the standard you need.
Related variants include 316Ti (UNS S31635, EN 1.4571), stabilised with titanium, and 316H (S31609) with controlled higher carbon for high-temperature strength. See the grade equivalent chart.
Physical properties
| Property | 304 / 304L | 316 / 316L |
|---|---|---|
| Density, g/cm³ | 7.9 | 8.0 |
| Melting range, °C | approx. 1400–1450 | approx. 1375–1400 |
| Thermal conductivity at 100 °C, W/m·K | approx. 16 | approx. 16 |
| Modulus of elasticity, GPa | approx. 193 | approx. 193 |
| Magnetic (annealed) | No | No |
Typical values from recognised industry references, for guidance only; they are not specification limits.
Corrosion resistance
316 resists a wider range of environments than 304: coastal and marine atmospheres, brackish water, many chloride-bearing process streams, dilute sulphuric and phosphoric acids, acetic and other organic acids, and the cleaning and sterilising chemicals used in food and pharmaceutical plants. In warm seawater and concentrated chloride solutions it can still pit and suffer crevice corrosion, and austenitic grades remain susceptible to chloride stress corrosion cracking above about 60 °C; for those conditions, duplex 2205, super duplex, 904L or 6% molybdenum grades are considered. 316L is resistant to sensitisation during welding; for sustained service in the 425–860 °C range, 316H or 316Ti may be specified.
SS 316 products we supply
- SS 316 pipes – seamless and welded, ASTM A312 TP316/316L.
- SS 316 sheets and plates – ASTM A240 316/316L.
- SS 316 round bars – ASTM A276/A479.
- SS 316 flanges – ASTM A182 F316/316L.
- SS 316 pipe fittings – ASTM A403 WP316/316L and A182 F316/316L.
- Fasteners in A193 B8M / A194 8M – see the stainless steel page for all forms.
Comparable grades
SS 304 has no molybdenum and costs less; it is adequate for fresh water, food and atmospheric exposure away from chlorides. SS 904L has much higher nickel and molybdenum plus copper, for sulphuric and phosphoric acids and stronger chloride conditions. 317L, with more molybdenum than 316L, sits between them and is used in flue gas desulphurisation and some chemical plants. Duplex 2205 offers higher strength and chloride stress corrosion resistance at a similar price to 316L in many forms.
Typical applications of SS 316
316 and 316L are used for chemical and petrochemical process equipment, pharmaceutical and biotech vessels and piping, dairy and brewery plants using chlorinated sanitisers, marine fittings and boat hardware, coastal architecture and balustrades, desalination pre-treatment, pulp and paper equipment, surgical and dental instruments in the 316L variant, and heat exchangers with brackish cooling water. In each case the reason is the same – better resistance than 304 to chlorides and acids, at a moderate cost increase.
Fabrication
316 and 316L form and weld much like 304, using 316L filler metal so that the weld keeps its molybdenum. They work-harden during forming and machining. After welding, heat tint is removed and the surface pickled and passivated to restore full corrosion resistance; this step matters more for 316 than 304 because it is usually chosen for harsher environments.
Frequently Asked Questions
SS 316 contains about 16–18% chromium, 10–14% nickel and 2–3% molybdenum, with 0.08% maximum carbon (0.030% for 316L in ASTM A240).
The 2–3% molybdenum in 316 improves its resistance to pitting and crevice corrosion caused by chlorides. It is still not fully resistant to warm seawater, where duplex or higher alloys are used.
SS 316L corresponds to EN 1.4404 (X2CrNiMo17-12-2), and 316 to EN 1.4401 (X5CrNiMo17-12-2). Japanese equivalents are SUS316L and SUS316.
316L has a lower maximum carbon content, which prevents sensitisation in welds. Its minimum strength is slightly lower than 316. Material is often dual certified 316/316L.
316Ti (UNS S31635, EN 1.4571) is 316 stabilised with titanium to resist sensitisation at elevated temperatures. It is common in European specifications.
The typical density of SS 316 is about 8.0 g/cm³ (8,000 kg/m³), slightly higher than 304 because of its molybdenum and nickel content.
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