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316 stainless steel (UNS S31600) is an austenitic chromium-nickel stainless steel that contains 2.00-3.00% molybdenum. The molybdenum is what separates it from plainer austenitic grades: it raises resistance to pitting and crevice corrosion in chloride-bearing media. It is not immune to corrosion, and a datasheet value is a reference point rather than a design limit.
This guide is for lab, clinic and procurement staff who meet “316” on a specification, certificate or product listing and need to know what the grade is, what its numbers mean, and where its resistance stops. It is general materials information, not a recommendation for any particular product or use.
Short answer
316 is a stainless steel with 16.00-18.00% chromium, 10.00-14.00% nickel and 2.00-3.00% molybdenum, with a carbon limit of 0.08% (United Performance Metals datasheet, checked 2026-10-30). Its molybdenum content gives better pitting and crevice resistance in chlorides than a grade without it, but chlorides, high temperature and strongly oxidizing conditions can still damage it.
Definition and scope
“316” is the grade name; the Unified Numbering System designation for the standard grade is S31600. The low-carbon variant, 316L (S31603), has the same limits except a carbon maximum of 0.030%. ATI describes 316 as an austenitic stainless steel supplied as plate, sheet and strip to ASTM A240 / ASME SA-240. The page you are reading covers the standard grade only; for the carbon difference, see 316 vs 316L, and for the contrast with the more common grade, see 304 vs 316 stainless steel.
316 stainless steel properties
Every value below comes from the manufacturer or distributor data sheet named in the last column. Treat them as typical or minimum reference values, not guarantees for a specific lot.
| Property | Value for 316 (S31600) | Source |
|---|---|---|
| Chromium | 16.00-18.00% | United Performance Metals; ATI |
| Nickel | 10.00-14.00% | United Performance Metals; ATI |
| Molybdenum | 2.00-3.00% | United Performance Metals; ATI |
| Carbon | 0.08% maximum (316L: 0.030% maximum) | United Performance Metals |
| Manganese / silicon | 2.00% / 0.75% maximum | United Performance Metals |
| Nitrogen | 0.10% maximum | United Performance Metals |
| Yield strength | 30 ksi (205 MPa) minimum | ATI; United Performance Metals |
| Tensile strength | 75 ksi (515 MPa) minimum | ATI; United Performance Metals |
| Elongation | 40% minimum | ATI |
| Hardness | 95 HRB maximum | ATI |
| Density | 0.29 lb/in³ (about 8.03 g/cm³) | ATI; United Performance Metals |
| Modulus of elasticity | 29 × 10⁶ psi (200 GPa) | United Performance Metals |
| Melting range | 2540-2630 °F (1390-1440 °C) | United Performance Metals |
The United Performance Metals datasheet states that its technical data is “for information only and not for design purposes.”
316 stainless steel chemical resistance: how molybdenum helps
Outokumpu states that adding molybdenum and nitrogen increases stainless steels’ resistance to pitting, and that stainless steels are “particularly susceptible to pitting and crevice corrosion in media containing halide ions such as chlorides.” Seawater and process solutions with high chloride concentrations are named as high-risk media.
Both Outokumpu and ASSDA publish the pitting resistance equivalent number (PRE) as a rough way to compare grades. Outokumpu prints it as PRE = %Cr + 3.3 × %Mo + 16 × %N; ASSDA prints a version that adds a tungsten term. Outokumpu cautions that PRE “only gives an indication” and should be used only for rough comparison.
Worked example: the PRE range inside the 316 limits
This is our own arithmetic using the Outokumpu formula and the composition limits above, not a figure published by either source.
- Lowest case (Cr 16.00, Mo 2.00, N 0): 16.00 + 3.3 × 2.00 = 22.6.
- Highest case without nitrogen (Cr 18.00, Mo 3.00, N 0): 18.00 + 3.3 × 3.00 = 27.9.
- Adding the 0.10% nitrogen maximum contributes up to 1.6 more, so the top of the range is about 29.5.
ASSDA states that stainless steels with a PRE above 40 resist ambient-temperature seawater. The whole 316 range sits well below 40, which is a practical reason not to read “316 resists chlorides” as “316 is suitable for seawater.”
Limits of that resistance
Outokumpu gives a chloride stress-corrosion-cracking threshold above 60 °C for chloride environments, and notes that in strongly oxidizing environments molybdenum “has proved to be detrimental to corrosion resistance.” Neither statement is specific to 316, but both apply to its composition, which depends on molybdenum. For the underlying passive-film mechanism see stainless steel corrosion resistance; for specific chemicals use a compatibility chart such as chemical compatibility of wetted materials instead of a general claim.
Where 316 appears in lab and supply decisions
The United Performance Metals datasheet lists these applications for alloy 316/316L: oil and petroleum refining equipment, aerospace structures, food processing equipment, pulp and paper processing equipment, soap and photographic handling equipment, textile industry equipment, architectural uses and pharmaceutical processing equipment. For lab and facility purchasing, the useful point is what to quote so that a requirement is unambiguous:
- Grade and UNS number: 316 / S31600, or S31603 if the low-carbon grade is intended.
- Product specification: ASTM A240 covers plate, sheet and strip; see ASTM A240.
- Carbon cap: 0.08% for 316 versus 0.030% for 316L, so the two are not interchangeable on paper.
- Surface treatment: if a finishing step such as passivation matters, it is a separate requirement; see passivation of stainless steel.
Common misunderstandings
- “Stainless means it cannot corrode.” Chloride pitting and crevice corrosion are documented failure modes for stainless steels, 316 included.
- “More molybdenum is always better.” Outokumpu reports the opposite in strongly oxidizing environments.
- “A PRE number is a rating.” It is a rough comparison tool only.
- “The datasheet is a design value.” The distributor’s own datasheet says it is not for design purposes.
Frequently asked questions
What is 316 stainless steel made of?
Iron with 16.00-18.00% chromium, 10.00-14.00% nickel, 2.00-3.00% molybdenum, and limits on carbon (0.08% maximum), manganese, silicon, phosphorus, sulfur and nitrogen.
What are the properties of 316 stainless steel?
Minimum yield of 30 ksi (205 MPa), minimum tensile strength of 75 ksi (515 MPa), at least 40% elongation and a density of about 8.03 g/cm³; see the table above.
What is the chemical resistance of 316 stainless steel?
Molybdenum improves resistance to pitting and crevice corrosion in chlorides compared with grades without it, but resistance is limited in strong chloride media, at elevated temperature and in strongly oxidizing environments. Check specific chemicals against a compatibility source.
Is 316 better than 304?
The two differ mainly in molybdenum; the comparison, including a magnet-test note, is in 304 vs 316 stainless steel.
What is the difference between 316 and 316L?
The carbon limit: 0.08% for 316, 0.030% for 316L. See 316 vs 316L for the full comparison.
Sources
- United Performance Metals, Alloy 316/316L datasheet (AMS 5507/5524/5648, UNS S31600/S31603), checked 2026-10-30.
- ATI, ATI 316 (UNS S31600), checked 2026-10-30.
- Outokumpu, Corrosion resistance, checked 2026-10-30.
- ASSDA, Corrosion, checked 2026-10-30.
