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Stainless Steel

304 Stainless

304 is the most common austenitic stainless steel, an 18-8 Cr-Ni alloy that is the default for general corrosion resistance. It is non-magnetic, highly ductile (around 40% elongation), and easily formed and welded. It is not hardenable by heat treatment but work-hardens, gaining strength as it is cold-worked.

How 304 Stainless machines

One of the harder metals to machine (rated 2.5/5). It work-hardens rapidly, so dwelling or rubbing creates a hard skin that wrecks tools; the key is positive rake, sharp-edged carbide, firm constant feeds to stay under the hardened layer, rigid setups, and copious coolant. Chips are stringy and gummy. For machined stainless, 303 or 416 are far easier.

Manufacturing & processing

Suited to CNC machining and especially sheet metal forming, where its ductility allows deep drawing and bending. It welds excellently by TIG/MIG (using matched filler such as 308L) and is a mainstay of fabricated stainless. It is passivated for maximum corrosion resistance and electropolished for hygienic or cosmetic finishes; it cannot be heat-treated to harden.

Typical applications

Used wherever general corrosion resistance is needed: kitchen and food-processing equipment, sinks and countertops, tanks and vessels, piping and fittings, architectural panels and trim, fasteners, medical and lab hardware, and chemical and dairy equipment. It is the default stainless for clean, corrosion-resistant, formed or fabricated parts.

When to choose it

Choose 304 as the default corrosion-resistant stainless for general environments, forming, and welding. Step up to 316 when chlorides or marine/medical exposure demand more resistance. Pick 303 or 416 when you need an easily machined stainless for turned parts, or a 400-series grade when you need a hardenable, magnetic stainless.

Suitable surface finishes

Common finishes for 304 Stainless: passivation, electropolishing, bead blasting, brushed. Use the finish selector →

FAQ

Is 304 stainless easy to machine?
No, it is challenging (rated 2.5/5) because it work-hardens rapidly. If the tool rubs or dwells, the surface hardens and destroys the edge. Success needs sharp positive-rake carbide, firm continuous feeds, rigid setups, and plenty of coolant. For easier-machined stainless parts, use free-machining 303 or 416 instead.
Can 304 stainless be hardened by heat treatment?
No. As an austenitic stainless, 304 cannot be hardened by heat treatment; it can only be strengthened by cold working (work hardening). For a hardenable stainless, use a martensitic grade like 410 or 416, or a precipitation-hardening grade like 17-4 PH, which reach high hardness through heat treatment.
What is the difference between 304 and 316?
316 adds molybdenum, giving markedly better resistance to chlorides, salt, and pitting (corrosion rated 5.0 vs 4.5 here), making it the choice for marine, medical, and chemical service. 304 is cheaper and adequate for most general environments. Choose 316 when chloride exposure is significant, 304 otherwise.

Property values are typical/nominal for early guidance and vary by temper, grade, supplier and heat treatment. Confirm critical specs against a certified datasheet or with an mfgiq engineer.