Not one material, but a family

Stainless steel is not a single material. It is a family of grades, each balancing corrosion resistance, strength, formability and cost differently. Pick the wrong one and you either pay for properties you never use, or watch a “stainless” part begin to pit and rust within a year.

The coil is where most projects start. From a single coil, fabricators produce kitchen equipment, storage tanks, architectural panels, railings and marine fittings. At Shandong Baimaoxing Steel Co., Ltd. we supply cold-rolled and hot-rolled coils across the standard grades, with surface processing from 2B to mirror polish. This guide covers the four grades buyers ask about most — 201, 304, 316L and 430 — and what each one is actually for.

The four grades we ship most

304 · The workhorse

Figure 2. 304 coil in a food-processing context

An austenitic grade with roughly 18% chromium and 8% nickel, 304 is the default for food processing, kitchen equipment, brewing and general fabrication. It forms, welds and polishes well, and stays non-magnetic in the annealed condition. When a buyer is unsure which grade they need, 304 is usually the answer.

316L · Built for salt and chemicals

Figure 3. 316L coil against a marina backdrop

316L adds 2–3% molybdenum to the 304 recipe, which gives it real resistance to chlorides — sea air, de-icing salts, pool chemicals. The “L” means low carbon (0.03% max), so welds keep their corrosion resistance. It is the grade for marine hardware, coastal construction, chemical plant and medical instruments. It costs more, and in these environments it earns it.

201 · The budget option

Figure 4. 201 coil in a light-industrial plant

201 replaces part of 304’s nickel with manganese and nitrogen, which brings the price down noticeably. It still looks like stainless and behaves acceptably indoors, but its corrosion resistance sits clearly below 304, and it is not suited to damp, salty or chemically aggressive conditions. Fine for indoor fixtures, light industry and decorative parts in mild environments.

430 · Magnetic and economical

Figure 5. 430 coil with an architectural interior backdrop

430 is a ferritic grade — chromium-based, with essentially no nickel. It is magnetic, easy to form and cheaper than the austenitic grades. Its corrosion resistance suits indoor and lightly exposed work: appliance panels, elevator cladding, automotive trim and decorative profiles, where a clean surface and a low price are what matter.

Side by side: the four grades

The composition ranges below follow the common international standards for these grades (ASTM A240, JIS G4305, GB/T 3280). Magnetism refers to the annealed condition — austenitic grades can pick up slight magnetism after heavy cold working.

Table 1. Comparison of the four grades

Cost is relative and varies with market prices for nickel and molybdenum; 316L is the most expensive of the four mainly because of its higher nickel and molybdenum content.

Marine environments: does 316L beat 304?

For salt-water exposure, the short answer is yes — and it is not a marginal difference. Marine corrosion is driven by chlorides, which attack stainless steel through pitting and crevice corrosion. 304 is susceptible: in splash zones and tidal areas it pits, discolours, and can fail within a couple of seasons. The molybdenum in 316L roughly doubles its pitting resistance, which is why 316L is the accepted standard for boat fittings, docks, coastal facades and seaside restaurants.

Upgrading from 304 to 316L in a marine application is rarely a luxury. It extends service life, cuts maintenance and avoids early replacement — the extra material cost usually pays for itself on the first repair bill it prevents.

Two practical notes. Keep welds clean and fully passivated, and never let carbon-steel tools or grinding dust touch the surface. Grade choice matters, but good practice matters just as much.

Table 2. 304 vs 316L for marine use

Surface finish: the other half of the decision

The grade decides how a coil resists corrosion; the finish decides how it looks, how it behaves in contact with food or chemicals, and what it costs. These are the finishes we process most.

Figure 6. Brushed, mirror-polished and 2B surfaces compared

Table 3. Common surface finishes

Brushed and mirror finishes are produced after cold rolling; pick the finish together with the grade, since deep polishing reveals any surface defect in the coil.

Choose the grade for the environment

Pick the grade for the environment, the finish for the application, and most of the guesswork disappears. If an application sits near salt water, chlorides or aggressive chemicals, 316L is the honest recommendation — not the cheapest one, but the one that stays intact.

Shandong Baimaoxing Steel Co., Ltd. supplies 201, 304, 316L and 430 coils, cold-rolled and hot-rolled, from standard 2B and brushed surfaces to mirror polish.

Send our sales team your grade, thickness, width and finish — we will quote accordingly.