304 is the general-purpose austenitic stainless: good corrosion resistance, good weldability, food-safe, and available everywhere. It is also the grade that teaches new buyers about work hardening — dwell with a dull tool and the surface gets harder than the tool.
| Tensile strength | 505 MPa |
|---|---|
| Yield strength | 215 MPa |
| Hardness | 92 HRB |
| Density | 8.00 g/cm³ |
| Elongation | 40% |
| Thermal conductivity | 16.2 W/m·K |
| Series | Austenitic (18/8) |
Typical values for the standard condition (Stainless Steel 304 / 304L). Heat treatment, temper and product form move these numbers — confirm against the mill certificate for your order.
Good corrosion resistance in most atmospheric and food-service environments
Excellent weldability and formability
Food-safe and widely accepted in hygienic applications
Available in every form at low cost relative to other stainless grades
Starting parameters for carbide tooling. These are the shop's working numbers, not brochure values — adjust for machine rigidity, tool geometry and workholding.
| Surface speed | 60–120 m/min |
|---|---|
| Feed per tooth | 0.05–0.15 mm/tooth |
| Tooling | AlTiN or TiAlN coated carbide, 4–5 flute for rigidity |
| Coolant | High-pressure flood, essential not optional |
Work-hardens fast. Never dwell or rub — if the tool stops moving it hardens the surface and destroys the next pass. Rigidity matters more than speed; a light, fast cut beats a heavy, slow one.
Slower cutting (roughly a quarter of aluminum speeds) and higher material cost roughly double the part price versus 6061. Passivation is normally included; electropolishing is a separate operation.
For the full cost structure — material, programming, setup, cycle time, finishing and inspection — see CNC machining cost per hour, and for how price changes with quantity see machining by production volume.
It work-hardens under the cutter and conducts heat poorly, so heat stays at the cutting edge instead of dissipating into the workpiece. Surface speeds are roughly a quarter of aluminum, and the tool needs to stay sharp and keep moving. A dwell or a dull edge hardens the surface and ruins the next pass.
316L adds molybdenum, which substantially improves resistance to chlorides and acids. It is the grade for marine, chemical and medical applications. 304 is fine for food service and general atmospheric exposure but will pit in salt or chloride-rich environments.
Yes, normally. Machining leaves embedded iron and disrupts the passive oxide layer, which is where rust starts. Passivation (a nitric or citric acid bath) removes free iron and restores the oxide layer. It is a standard line item on machined 304 parts, not an upgrade.
Annealed 304 is essentially non-magnetic, but cold working — including machining and deep forming — can make it slightly magnetic in the worked areas. If non-magnetic behavior is a functional requirement, specify it and expect to discuss the cold-work history of the part.
Tell us the grade and temper, the quantity and what the part has to do. You get a line-item quote within 24 hours, with DFM feedback on anything that is raising the cost.