If you need one sentence to pick a stainless steel grade, here it is: use 304 for general indoor and mild-corrosion work, 316L wherever chlorides or welding are involved, 2205 where you need roughly double the strength of 304 with better chloride resistance, and 430 only for dry, non-critical, magnetic applications on a tight budget. The grade decision is made against three questions — how corrosive is the environment, will it be welded, and how much strength does it need — and the table below maps every common grade to those three answers (each linked to its full stainless grade page).
Quick-reference table
| Grade | UNS | Type | Chloride resistance | Weldable | Typical use |
|---|---|---|---|---|---|
| 304 | S30400 | Austenitic | Moderate | Yes (use 304L for weld) | General indoor, kitchen, trim |
| 304L | S30403 | Austenitic | Moderate | Yes — low carbon | Welded tanks and frames |
| 316 | S31600 | Austenitic | Good | Yes | Chemical, food process |
| 316L | S31603 | Austenitic | Good | Yes — low carbon | Marine, pharma, welded pipe |
| 2205 | S32205 | Duplex | Excellent | Yes | Offshore, heat exchanger, structural |
| 201 | S20100 | Austenitic | Low | Fair | Decorative, low-cost indoor |
| 430 | S43000 | Ferritic | Low | Poor (magnetic) | Appliance trim, non-critical |
| 321 | S32100 | Austenitic | Moderate | Yes — titanium stabilized | High-temperature welded service |
| 310S | S31008 | Austenitic | Moderate (heat) | Yes | Furnace, high-temperature |
Values and uses are typical, not acceptance limits. The grade that governs your part is confirmed on the mill certificate for your heat.
The three questions, in order
How corrosive is the environment? This is the PREN question. Pitting resistance is measured by PREN = Cr + 3.3 Mo + 16 N. 304 sits around 18–19, 316L around 24–26, 2205 above 30. Above roughly PREN 24 the material resists the chloride levels that start pitting 304 — which is why anything coastal, chlorinated or marine defaults to 316L or 2205.
Will it be welded? If yes, use an L grade (304L, 316L) or a stabilized grade (321). Welding a plain 304 or 316 can precipitate chromium carbides at the grain boundary and leave the joint vulnerable to intergranular attack. The low-carbon and stabilized grades survive welding without a post-weld anneal.
How much strength? 304 and 316L are roughly equal in strength. If you need roughly double the yield strength with better chloride resistance, 2205 duplex is the answer — and it often lets you use a thinner section, which offsets some of its cost.
Where each grade goes wrong
- 304 in a marine or chlorinated environment will pit. Upgrade to 316L.
- 430 welded or outdoors will corrode and is magnetic, so it fails where appearance or structure matters.
- 201 in a humid or coastal setting has only modest corrosion resistance; it is a decorative, low-cost grade, not a structural one.
- 316L below the waterline in a hot, stagnant, chloride-rich zone can still suffer crevice corrosion; where that matters, 2205 or a higher alloy is the answer.
How to order against this table
Name the grade, the environment and the weld condition in your first message. A 304 request that turns out to be coastal is corrected to 316L before quoting, not after the part fails. State the service — salt air, food contact, temperature, welded or not — and the right grade, form and certificate type come back in the same reply.