Stainless 304 (UNS S30400)
Stainless 304 (UNS S30400) — General-purpose 18-8 stainless steel.
| UNS number | S30400 |
| Material family | Austenitic stainless |
| Product specifications | A182 F304, A403 WP304, A312 TP304 |
| Density (typical) | 7.93 g/cm³ (7930 kg/m³) |
| Weight of 6" Sch 40 pipe | 28.55 kg/m |
Specifications by product form
One alloy is ordered under different ASTM/ASME numbers depending on form: forged flanges and fittings, wrought buttweld fittings, and pipe or tube. For Stainless 304 the usual specifications are A182 F304, A403 WP304, A312 TP304. Quote both the specification and the UNS number on purchase orders to avoid ambiguity.
Chemical and mechanical limits differ between these specifications — always check the edition of the standard named on your order and the mill test certificate.
Chemical composition & mechanical properties
| Property | SS 304 |
|---|---|
| Family | Austenitic stainless |
| UNS | S30400 |
| EN / W.Nr | 1.4301 X5CrNi18-10 |
| Basis spec | ASTM A240 |
| Density g/cm³ | 7.93 |
| Chemical composition, % | |
| C | 0.07 |
| Mn | 2.00 |
| P | 0.045 |
| S | 0.030 |
| Si | 0.75 |
| Cr | 17.5–19.5 |
| Ni | 8.0–10.5 |
| N | 0.10 |
| Mechanical properties (min) | |
| Tensile strength | 515 MPa (75 ksi) |
| Yield strength (0.2%) | 205 MPa (30 ksi) |
| Elongation | 40% |
| Hardness (max) | 201 HB |
| PREN (min, from spec) | 17.5 |
Single values are maximums; ranges are min–max; "bal" = balance. Limits are typical of the basis specification for that product form — forgings, pipe and fittings specifications differ slightly. Always check the exact specification, edition and the mill test certificate.
Frequently asked questions
What is the UNS number of Stainless 304?
S30400.
Which ASTM specifications cover Stainless 304?
A182 F304, A403 WP304, A312 TP304.
What is the density of Stainless 304?
About 7.93 g/cm³ (7930 kg/m³), used for weight calculations.
Last updated 2026-11-02