Not when annealed. Cold working (bending, drawing, machining) can make it slightly magnetic; this does not mean it is a lower grade.

SS304 or SS316: which should I use?

SS316 contains molybdenum and resists salt water and chlorides much better. Use 304 for general and food use, and 316 for marine, chemical and coastal conditions.

Can SS304 be hardened?

Not by heat treatment. It becomes harder only by cold working. For a hardenable stainless steel, use SS410 or SS420.

It resists rust in normal conditions, but it can stain or pit in chlorides or where iron particles are left on the surface. Cleaning and passivation keep it bright.

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SS304 stainless steel

Also called: AISI 304, 1.4301, X5CrNi18-10, SUS304, 18/8 stainless, 304L

SS304 is the most widely used stainless steel: an austenitic grade with about 18% chromium and 8% nickel ("18/8"). It resists rust in air, water and most foods and chemicals, is easy to form and weld, and cannot be hardened by heat treatment.

Quick facts

Type: Austenitic stainless steel
Main alloys: About 18% chromium, 8% nickel
Tensile strength: About 515 MPa min (annealed)
Yield strength: About 205 MPa min (annealed)
Magnetic?: Non-magnetic when annealed; slightly magnetic after cold work
Hardening: Not by heat treatment; only by cold work

Equivalent grades

Standard	Closest grade
AISI / ASTM	304 (UNS S30400); low-carbon 304L (S30403)
EN / DIN	1.4301 (X5CrNi18-10); 304L = 1.4307
IS 6911 (India)	X04Cr19Ni9
JIS	SUS304

Typical chemical composition

Element	%
Carbon (C)	0.08 max (304L: 0.03 max)
Chromium (Cr)	18.0–20.0
Nickel (Ni)	8.0–10.5
Manganese (Mn)	2.0 max
Silicon (Si)	0.75 max

Limits differ slightly between product standards (sheet, bar, pipe).

304 or 304L?

304L has less carbon, so it does not lose corrosion resistance next to welds. Choose 304L for welded tanks, vessels and pipework; 304 is fine for parts that are not welded or are welded thinly.

Corrosion limits

Good in air, fresh water, food and most mild chemicals
Can pit in salt water, chlorides and coastal air: choose SS316 there
Avoid contact with plain carbon steel tools and dust during fabrication, which leaves rust spots; passivation restores the surface

Machining and welding

SS304 work-hardens, so tools must be sharp and keep cutting rather than rub; it machines more slowly than carbon steel. It welds easily by TIG and MIG without preheating.

Typical uses

Food, dairy and pharmaceutical equipment
Kitchen equipment and sinks
Tanks, vessels and pipework
Fasteners, fittings and architectural trim
Chemical and textile machinery parts

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Questions

Is SS304 magnetic?: Not when annealed. Cold working (bending, drawing, machining) can make it slightly magnetic; this does not mean it is a lower grade.
SS304 or SS316: which should I use?: SS316 contains molybdenum and resists salt water and chlorides much better. Use 304 for general and food use, and 316 for marine, chemical and coastal conditions.
Can SS304 be hardened?: Not by heat treatment. It becomes harder only by cold working. For a hardenable stainless steel, use SS410 or SS420.
Does SS304 rust?: It resists rust in normal conditions, but it can stain or pit in chlorides or where iron particles are left on the surface. Cleaning and passivation keep it bright.

The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 8 October 2026.