Metal
Stainless 316L
Marine and medical stainless. Molybdenum for chloride resistance.
Published values for unfilled grades at 23 °C unless stated. Confirm against the supplier datasheet for the grade you specify.
What it is
316L adds 2–3 % molybdenum to the 304 chemistry, which sharply improves resistance to chlorides: seawater, saline, de-icing salt, and many process chemicals that pit 304.
The L designation means low carbon, which prevents chromium carbide forming at grain boundaries during welding. It is the standard stainless for surgical instruments, implants, and pharmaceutical process equipment.
Where it is used
- Surgical instruments and implantable components
- Pharmaceutical and biotech process equipment
- Marine hardware and fittings
- Chemical processing components
- Cleanroom and sterile equipment
Processing notes
Machines like 304, only slightly harder. Rigid setups, sharp tools, no dwelling.
Weld with 316L filler and back-purge to protect the root pass.
Electropolish for medical and pharmaceutical parts; it removes the machining-damaged surface layer and improves passivation.
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Design notes
Surface finish is a functional specification in hygienic design. Call out Ra explicitly, typically Ra 0.8 µm or better for product contact.
Design out crevices, dead legs, and horizontal ledges in any wetted assembly.
If the part is an implant or a patient-contact device, specify the standard, not just the grade: ASTM F138 for implant bar stock.
Grades and variants
- 316L, the standard low-carbon grade
- 316, standard carbon, non-welded applications
- ASTM F138, implant quality bar
- 2205 duplex, higher strength for structural marine parts
- 904L, for severe chemical service
Alternatives
If Stainless 316L is not the right answer
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