Stainless Steel A2 (304)

Family

Metals

Category

stainless

Density

7.9 g/cm³ · 7900 kg/m³

Typical property classes

A2-70 Stainless (304), A2-80 Stainless (304)

Grade

304 · UNS S30400

Governing standard

ASTM A276 (bar) · ASTM A240 (plate, sheet and strip)

Yield strength

205 MPa

Tensile strength

515 MPa

Modulus of elasticity

193 GPa

Hardness

≤ 201 HB

These are the annealed-condition minimums. The A2-70 and A2-80 classes listed on this page reach their strength by cold working, not by alloying: A276 sets higher minimums for cold-finished bar up to 12.7 mm — 620 MPa tensile, 310 MPa yield.

Minimum values specified by ASTM A276.

Machining

Gummy. It work-hardens under the cut, so light feeds, sharp tooling and a rigid setup matter more than speed — 304 is one of the harder common alloys to get a clean finish on.

Corrosion

Good general resistance and no rusting in ordinary atmosphere. Weak against chlorides: it pits in salt water and in pool water.

Welding

Readily welded by all the common processes, with no preheat and no post-weld heat treatment needed on standard 304.

Like the workability notes on the wood pages, these lines are not measurements. They carry no units and no single source, and the ratings they mention are relative — a machinability figure is quoted against a bench-mark alloy, not against an absolute scale. Read them as the consensus of the trade, not as a specification.

• Good corrosion resistance in normal atmosphere
• Slightly magnetic when cold worked

Which tools work a material is a property of the family (Metals), not of the individual species — so this list is the same on every metals page, and changes when the tool data changes rather than when this paragraph does.