Choose 316 when the part lives near the sea, around chlorides, pool chemicals, or harsh cleaning agents. For indoor, inland, and food-contact parts that don't see salt, 304 does the job at a lower price.
That's the rule we give most customers, and it holds up. The two grades look identical on the shelf and cut, bend, and weld almost the same way. The difference only shows months later, as brown tea staining on a balustrade fitting in Gqeberha, or small pits in a pool pump cover. Here's what actually separates them, where the line falls in South Africa, and a few cases where people pay for 316 they didn't need.
What's the difference in the metal?
Both are austenitic stainless steels: non-magnetic when annealed, easy to form, and widely available as sheet. The key difference is one extra alloying element.
| 304 | 316 | |
|---|---|---|
| Chromium | About 18% | About 16–18% |
| Nickel | About 8% | About 10–14% |
| Molybdenum | None | About 2–3% |
| Resistance to chlorides (salt) | Moderate | Much better |
| Pitting and crevice corrosion | More prone | More resistant |
| Magnetic? | No (when annealed) | No (when annealed) |
| Relative cost | Lower | Higher |
| Typical uses | Kitchens, shopfitting, inland architecture | Coastal, marine, pools, chemical plant |
The molybdenum is the point. It makes 316 much better at resisting pitting and crevice corrosion, the small, deep attacks caused by chlorides. Chlorides come from sea salt, swimming pool chlorine, de-icing salts, some cleaning chemicals, and many industrial processes.
The higher nickel and the molybdenum are also why 316 costs more.
Where 304 is the right choice
304 is the general-purpose stainless steel, and for good reason. Use it for:
- Kitchen and catering equipment, counters, and splashbacks
- Food processing, dairy, and brewing parts that aren't exposed to chlorides
- Shopfitting, display, and signage parts indoors
- Architectural trim and balustrade fittings inland, like Johannesburg, Pretoria, or Bloemfontein
- Machine guards and covers in clean industrial settings
Inland and indoors, 304 stays bright for years with basic cleaning. Paying for 316 there buys you very little.
Where people pay for 316 they don't need
We see 316 on drawings for parts that will never meet a grain of salt. A few common ones:
- Indoor kitchen equipment in an inland city. Unless there's salty product or chlorinated wash-down, 304 is the standard choice.
- Parts that will be powder coated. If the stainless is hidden under a coating, the grade's appearance doesn't matter, and on hidden industrial parts even 3CR12 may do.
- Brackets and covers inside a dry machine. No moisture, no chlorides, no reason for molybdenum.
- "Because it's the better one." Don't pick 316 because it sounds better. Pick it because the environment needs it.
On a large panel or a big production run, that choice can make a real difference to the quote.
Where 316 earns its price
Use 316 when chlorides are part of the environment:
- Coastal installations. Anything exposed outdoors in Durban, Cape Town, Gqeberha, East London, or other coastal towns. Salt spray carries inland too, especially in windy areas.
- Swimming pools and spas. Chlorinated water and the air around it are hard on 304.
- Marine fittings on boats, jetties, and harbour equipment.
- Chemical and process plant where chloride-containing products or cleaners are used.
- Food plants with aggressive cleaning, such as frequent chlorinated wash-downs.
The best metal for coastal work is a bigger topic than just the stainless grade. Our post on the best metal for coastal areas in South Africa compares 316 with aluminium, galvanising, and powder coated options.
The finish matters as much as the grade
Here's something that surprises people: a rough 316 surface can still tea-stain at the coast. Rough or scratched finishes trap salt and moisture, which is where staining starts, whatever the grade. The Australian stainless association (ASSDA) recommends 316 as a minimum within about 5 km of the surf, and a surface smoother than about 0.5 µm Ra on top of that.
For anything exposed outdoors near the coast:
- Choose a smooth finish, and if it's brushed, keep the grain vertical so rain can wash it.
- Avoid crevices and pockets where water and salt sit.
- Clean welds properly. Heat tint left on a weld is a weak spot regardless of grade.
- Wash it down now and then. Rain does this on open surfaces, but sheltered areas under eaves get no rinse, and that's where staining shows first.
Our guide to stainless steel sheet finishes explains the options.
What about 304L and 316L?
The L grades are low-carbon versions, with a maximum of 0.03% carbon instead of 0.08%. Lower carbon reduces the risk of a problem called sensitisation, where chromium carbides form near welds and leave those areas less corrosion-resistant. For heavily welded parts, particularly in thicker sheet, the L grades are a sensible default, and many suppliers stock dual-certified material that meets both specifications. Ask about it on the quote if welding is a big part of the job.
Fabrication: almost no difference
From a workshop point of view, 304 and 316 behave very similarly.
- Laser cutting: both cut cleanly, usually with nitrogen for a bright, oxide-free edge.
- Bending: both spring back more than mild steel and need an inside radius of roughly 1.5–2× thickness as a starting rule.
- Welding: both distort more than mild steel and form heat tint that should be cleaned off.
- Magnetism: both are non-magnetic when annealed, but bending can make them slightly magnetic near the folds. That's normal and doesn't mean it's the wrong grade.
If a cheaper grade is on your mind for hidden industrial parts, compare 3CR12 vs 304 stainless steel as well.
Getting it made
Put the grade, thickness, finish, and quantity on your quote. If you're not sure whether you need 316, tell us where the part will be installed and we'll help you choose. Our laser cutting service handles stainless steel along with mild steel, aluminium, and 3CR12. Start a quote for laser cutting and add bending and welding on the same order.