304 vs 316 Stainless
304 and 316 are the two austenitic stainless steels every shop stocks, and mechanically they are near twins: same yield and tensile minimums, same density, same modulus, both non-magnetic when annealed. The one composition change that matters is molybdenum. 316 carries 2 to 3% Mo (and a little more nickel), which is what lets it shrug off chlorides that pit 304.
So the decision is about the environment, not the load. Salt spray, seawater, de-icing brine, pool chemistry, many process chemicals and most medical or food-contact work push you to 316. Indoor, architectural, kitchen and general fabrication stay on 304 and save roughly a fifth to a third of the material cost.
| Property | 304 | 316 |
|---|---|---|
| Type | Austenitic 18/8 | Austenitic, Mo-bearing |
| Chromium | ~18% | 16–18% |
| Nickel | 8–10.5% | 10–14% |
| Molybdenum | — | 2–3% |
| Density | ~8.0 g/cm³ | ~8.0 g/cm³ |
| Yield (ASTM A240 min) | 205 MPa (30 ksi) | 205 MPa (30 ksi) |
| Tensile (ASTM A240 min) | 515 MPa (75 ksi) | 515 MPa (75 ksi) |
| Corrosion resistance | Good (general) | Better — chlorides, marine, chemical (Mo) |
| Magnetic (annealed) | No | No |
| Relative cost | Baseline | ~20–30% higher |
| Typical uses | Kitchen, architectural, general fab | Marine, coastal, chemical, medical |
Typical values for the stated conditions. Confirm against the mill certificate and your spec.
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Decision matrix
A check marks the side with the edge on that dimension.
| Dimension | 304 | 316 |
|---|---|---|
| Machining | ✓ Fair; gummy, work-hardens, needs rigid setups and positive tooling | Fair; slightly tougher on tools than 304, same rules |
| Welding | Excellent; 308L filler, L grade for heavy sections | Excellent; 316L filler, same practice |
| Forming | Excellent; deep draws and tight bends in annealed sheet | Excellent; marginally higher springback |
| Strength | 205 MPa yield min, work-hardens fast | 205 MPa yield min, work-hardens fast |
| Corrosion resistance | Good in fresh water, food, mild atmospheres; pits in chlorides | ✓ Better; molybdenum resists chloride pitting and crevice attack |
| Finishing | Passivates, electropolishes, takes No. 4 and mirror finishes | Identical finishing; electropolishes well for sanitary work |
| Material cost | ✓ Baseline stainless | About 1.2-1.3x, tracks nickel and molybdenum prices |
| Availability | ✓ Every form, every service center | Widely stocked; fewer sizes in tube and structural shapes |
Choose 304 when
- Indoor, architectural, kitchen or general fabrication with no chloride exposure
- Cost matters and the part is not going near salt, brine or aggressive chemicals
- You need an odd stock size or structural shape today
- Food equipment in non-chloride service where 304 is already the industry norm
Choose 316 when
- Marine, coastal or de-icing-salt exposure, including outdoor hardware near the ocean
- Chloride or chemical process contact: pharmaceutical, chemical, pulp and paper, pool equipment
- Medical devices, implants adjacent hardware and sanitary equipment that will be CIP cleaned
- The part will be electropolished and expected to stay stain-free for years outdoors
Frequently asked questions
- What is the main difference between 304 and 316?
- 316 contains 2–3% molybdenum, which sharply improves resistance to chlorides (salt, seawater, de-icing) and many chemicals. 304 has no molybdenum. Mechanically the two are nearly identical; the choice is almost always about corrosion environment and cost.
- Is 316 stronger than 304?
- Not meaningfully. Both meet the same ASTM A240 minimums (205 MPa yield, 515 MPa tensile, annealed). 316 is chosen for corrosion resistance, not strength.
- When should I pay for 316?
- Use 316 for marine/coastal exposure, chloride or chemical contact, and many medical/food applications. For indoor, architectural, and general fabrication, 304 is usually the cost-effective choice. 316 typically runs 20–30% more.
- Is 316 stainless magnetic?
- Not in the annealed condition; neither is 304. Both can pick up slight magnetism after heavy cold work, because deformation converts some austenite to martensite. 316 is a little more stable than 304, so it stays less magnetic after forming, but neither should be specified as fully non-magnetic without a test.
