Medical & surgical
Surgical instruments, fixation hardware, instrument trays. ASTM F138 implant-grade for short-term in-body use.
Austenitic stainless · UNS S31603
Stainless Steel 316L
Low-carbon austenitic stainless. Excellent corrosion resistance — especially against chlorides and seawater — and the standard for medical, surgical, food-contact, and marine parts where pitting is a real risk.
UTS
580 MPa
Density
8.0 g/cc
Modulus
193 GPa
Mach.
45 /100
When to use
Pick 316L when corrosion resistance is non-negotiable.
The "L" stands for low carbon (≤0.03%). Lower carbon means less carbide precipitation at grain boundaries during welding or thermal cycling — which directly translates to better corrosion resistance in harsh environments. 316L is what you spec when 304 has failed by pitting, or when the part will be welded.
The 2–3% molybdenum addition is the workhorse here: it dramatically improves resistance to pitting and crevice corrosion in chloride-rich environments. That’s why 316L dominates marine, food, and pharmaceutical hardware.
Strengths
Why 316L is the default.
- Chloride resistanceMo addition resists pitting in seawater, brine, sweat, and processed-food environments.
- WeldableLow carbon prevents sensitization — no post-weld heat treatment usually required.
- BiocompatibleStandard for surgical instruments and short-term implants. (For long-term implants, use 22-13-5 or implant-grade Ti.)
- CryogenicDuctility holds down to liquid nitrogen temperatures (−196 °C).
- Cosmetic finishPolishes well — ideal for food-grade, sanitary, and architectural surfaces.
Trade-offs
Where it falls short.
- Yield strengthYield (290 MPa) is the lowest of common stainless grades. Pick 17-4PH if structural strength matters.
- GallingAustenitic stainless self-galls under load. Use anti-seize on threads, or run thread inserts.
- Work hardensChips harden the work surface. Aggressive feeds, no dwell — same rules as Ti.
- Thermal expansion16 µm/m·°C — high enough that cryogenic-to-ambient parts need allowance.
- Magnetic when workedCold work induces some martensite. Annealed 316L is non-magnetic; machined surfaces may show weak magnetism.
Specs
Mechanical, physical & chemical data.
Typical values for solution-annealed 316L bar per ASTM A276. Cold work increases strength substantially at the cost of corrosion resistance and ductility.
Mechanical
Properties (annealed)
| Ultimate tensile strength | 580 MPa (84 ksi) |
|---|---|
| Yield strength (0.2% offset) | 290 MPa (42 ksi) |
| Elongation at break | 50% |
| Reduction of area | 65% |
| Modulus of elasticity | 193 GPa (28.0 Msi) |
| Shear modulus | 74 GPa |
| Poisson's ratio | 0.30 |
| Hardness (typical) | ≤95 HRB |
| Endurance limit 10⁷ cycles, R = -1 | 240 MPa |
Source: ASM Handbook Vol. 1; AK Steel datasheet. Cold drawn bar reaches ~860 MPa UTS.
Physical & thermal
Properties at room temp
| Density | 8.0 g/cc (0.289 lb/in³) |
|---|---|
| Melting range | 1375 – 1400 °C |
| Specific heat | 0.500 J/g·°C |
| Thermal conductivity | 16.3 W/m·K |
| CTE (0–100 °C) | 16.0 µm/m·°C |
| Electrical resistivity | 0.74 µΩ·m |
| Magnetic permeability Effectively non-magnetic when annealed | ≈1.008 |
Cold work raises permeability — fully cold-worked 316L can register on a magnet.
Composition
Chemistry, weight %
| Chromium (Cr) | 16.0 – 18.0 |
|---|---|
| Nickel (Ni) | 10.0 – 14.0 |
| Molybdenum (Mo) | 2.0 – 3.0 |
| Manganese (Mn) | 2.0 max |
| Silicon (Si) | 1.0 max |
| Carbon (C) The defining feature of 'L' grade | 0.03 max |
| Phosphorus (P) | 0.045 max |
| Sulfur (S) | 0.03 max |
| Nitrogen (N) | 0.10 max |
| Iron (Fe) | balance |
316LN adds N (0.10–0.16%) for higher strength while retaining low-C corrosion behavior.
Specifications
Common purchase specs.
ASTM A276
Stainless bar — general purpose
ASTM A479
Stainless bar — pressure parts
ASTM A484
Common requirements — bar/billet
AMS 5653
Bars, forgings, rings — solution annealed
ASTM F138
Surgical implant grade
ISO 5832-1
Implants for surgery
AISI 316L
Equivalent designation
EN 1.4404
European equivalent
Machining
How we cut it.
316L is the gummy cousin of 303 free-machining stainless. Where 303 chips and breaks cleanly, 316L tries to weld back to the tool. Sharp edges, positive rake, and constant feed.
Cutting speed
100–250 SFM with carbide. Slower than 4140 — work-hardening risk if you push too hard.
Feed rate
Aggressive, constant. Keep the chip continuous.
Tooling
Sharp positive-rake carbide. Coated grades extend tool life on production.
Coolant
Flood with water-soluble or sulfurized oil. Helps chip evacuation.
No dwell
Same rule as Ti. Stopping mid-cut work-hardens the surface.
Climb mill
Reduces work-hardening of the next pass's surface.
Threading
Use carbide inserts or single-point. HSS taps can gall — watch the lubricant.
Drilling
Peck cycles and frequent chip clearing. Deep holes need through-tool coolant.
Applications
Where 316L shows up.
Food & pharmaceutical
Process valves, fittings, mixing tank components. Polished 316L surfaces are easy to clean and don't harbor pathogens.
Marine & subsea
Boat hardware, deep-sea enclosures, valve bodies. Mo content prevents the chloride pitting that destroys 304.
Compare
Related materials.
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