304 Stainless Steel
304 is the most widely used austenitic stainless steel, offering good corrosion resistance and excellent weldability at moderate cost.
- Family /
- Stainless Steels
- Machinability /
- ~45%
- Condition /
- Annealed
- Also called /
- three oh four
304 is the most widely used austenitic stainless steel, offering good corrosion resistance and excellent weldability at moderate cost.
Machinability is approximate and rated against free-machining 1212 steel at 100%. Higher is easier to cut.
What it is
Roughly 18% chromium and 8% nickel, which is why it is sometimes called 18-8. It is non-magnetic in the annealed condition and cannot be hardened by heat treatment — only by cold work.
How it cuts
Considerably harder to machine than carbon steel. It is gummy, produces long stringy chips, and work-hardens aggressively if the tool rubs instead of cutting. It wants sharp tooling, a positive rake, rigid setups and a committed depth of cut.
What catches people out
Work hardening is the main trap. A light or dwelling pass hardens the surface ahead of the tool, and the next pass then has to cut through material harder than the original — which destroys tools quickly and is usually blamed on the material rather than the technique.
304 Stainless Steel — Common Questions
Can 304 stainless be hardened?
- Not by heat treatment. Austenitic grades like 304 only harden through cold work. If you need a hardenable stainless, 17-4 PH or a martensitic grade such as 410 is the right direction.
Why is machining 304 more expensive than carbon steel?
- It cuts at roughly half the rate, wears tooling faster, and work-hardens if the cut is not maintained. The material premium is real but the machining time is usually the larger part of the cost difference.
Other stainless steels
Got a part for 304 Stainless Steel?
Send the drawing or the sample. We will tell you straight what it will take to make.