316 Stainless Steel: Marine-Grade Properties, Composition & Applications
AISI 316 / ASTM A240 (UNS S31600) · Published: 2026-07-25 · Updated: July 2026
316 stainless steel is the standard 'marine-grade' austenitic stainless, adding 2-3% molybdenum to the 18-8 chromium-nickel chemistry of 304 to dramatically improve resistance to chloride pitting and crevice corrosion. This single alloying...
316 stainless steel is the standard 'marine-grade' austenitic stainless, adding 2-3% molybdenum to the 18-8 chromium-nickel chemistry of 304 to dramatically improve resistance to chloride pitting and crevice corrosion. This single alloying addition shifts 316 from a general-purpose stainless into the workhorse for coastal architecture, marine fittings, pharmaceutical piping, chemical process equipment, surgical implants, and food processing where salt or chloride exposure is possible. The standard 316 grade has a maximum 0.08% carbon, which is acceptable for as-rolled products and non-welded components. For welded fabrications exposed to corrosive service, the low-carbon variant 316l-stainless-steel/">316L (UNS S31603, ≤0.03% C) is strongly preferred to prevent sensitization in the heat-affected zone—eliminating the need for post-weld solution annealing. 316 has the same excellent formability, weldability, and non-magnetic character as 304, with a marginal cost premium of 25-40%. For the full UNS S31600 data sheet, see ss316l/">AISI 316L (UNS S31603).
Quick Facts
| Category | Stainless Steel |
| Standard | AISI 316 / ASTM A240 (UNS S31600) |
| Density | 8.00 g/cm³ |
| Yield Strength | 205 MPa (30 ksi) |
| Tensile Strength | 515 MPa (75 ksi) |
Detailed Mechanical Properties
| Elongation | 50% (annealed) |
| Hardness | 70-90 HB (annealed) |
| Charpy V Notch | >100J at -196°C |
| Modulus Of Elasticity | 193 GPa |
Physical Properties
| Melting Point | 1370-1400 °C |
| Thermal Conductivity | 16.3 W/m·K at 20°C |
| Electrical Resistivity | 0.000074 Ω·cm |
| Specific Heat | 500 J/kg·K |
Global Equivalents & Cross-Reference
| Alternative Standard / Grade | Action |
|---|---|
| AISI 316 | Compare |
| UNS S31600 | Compare |
| EN 1.4401 | Compare |
| SUS316 | Compare |
| 06Cr17Ni12Mo2 | Compare |
| X5CrNiMo17-12-2 | Compare |
Heat Treatment & Processing
| Solution Annealing | 1040-1120°C, water quench |
| Stress Relieving | 250-425°C (avoid 425-860°C) |
| Note | Cannot be hardened by heat treatment; strength is achieved only by cold work |
Welding & Fabrication
| Preheat | Not required |
| Filler Metal | ER316L (GMAW/GTAW), E316L-16 (SMAW) |
| Interpass Temp | Max 175°C |
| Weldability Rating | Excellent |
Related Materials
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Frequently Asked Questions
What is the difference between 316 and 316L stainless steel?
Only carbon content. Standard 316 has ≤0.08% carbon; 316L has ≤0.03% carbon. The 'L' (low-carbon) variant prevents chromium carbide precipitation during welding, eliminating intergranular corrosion (weld decay) in the heat-affected zone without post-weld solution annealing. 316L has marginally lower yield strength (~170 MPa vs 205 MPa for 316) but is otherwise similar. For welded components in corrosive service, always specify 316L.
Is 316 stainless steel truly marine-grade?
316 is the minimum recommended grade for marine atmospheric exposure (splash zones, coastal architecture within 5 km of saltwater). However, 316 will pit in continuous seawater immersion. For seawater immersion, specify a higher-alloy grade: duplex 2205 (PREN 35), super-austenitic 254 SMO (PREN 43), or nickel-based alloys like Inconel 625.
Why is 316 used for pharmaceutical and food equipment?
316/316L is specified by ASME BPE for pharmaceutical piping and 3-A sanitary standards for dairy and food processing because its molybdenum improves resistance to pitting in purified water loops, CIP (clean-in-place) chemical solutions, and salt-containing food products. 316L is also non-reactive with food acids and does not impart taste or odor.
How much more expensive is 316 than 304?
316 typically costs 25-40% more than 304 due to its higher nickel and molybdenum content. Specify 316 only when justified by chloride exposure or sanitary requirements—specifying it unnecessarily wastes project budget. For indoor, freshwater, or mild chemical service, 304 is the economical default.
Can 316 be used for surgical implants?
Yes, 316L (specifically ASTM F138 wrought and F139 conditions) is one of the standard implant alloys for fracture fixation plates, screws, and temporary orthopedic devices. For permanent joint replacement implants (hip, knee), titanium Ti-6Al-4V or cobalt-chromium alloys are preferred for their superior biocompatibility and fatigue strength.
References & International Standards
- ASTM International. Standard Specifications for Steel & Metal Alloys. astm.org
- International Organization for Standardization (ISO). Metallic Materials — Cross-Reference Database. iso.org
- American Iron and Steel Institute (AISI). Steel Grade Designations & Equivalents. steel.org
- European Committee for Standardization (CEN). EN Steel Standards & Numbering System. cencenelec.eu
Stainless & Corrosion-Resistant Steel — Engineering Reference
Stainless steels are defined by their chromium content (minimum 10.5%), which forms a self-healing passive layer of chromium oxide that resists corrosion. Grades are classified by microstructure: austenitic (300 series), ferritic (400 series), martensitic, and duplex.
ASTM A240/A276/A312, EN 10088, JIS G4304/G4305, GB/T 3280/4237
Food processing equipment, medical implants, chemical tanks, architectural cladding, marine hardware, pharmaceutical piping
For welded stainless fabrications, specify the low-carbon variant (304L, 316L) to prevent chromium carbide precipitation at grain boundaries, which causes intergranular corrosion (weld decay).