Stainless 321 (UNS S32100)
Stainless 321 (UNS S32100) — Titanium-stabilised for high-temperature service.
| UNS number | S32100 |
| Material family | Austenitic stainless |
| Product specifications | A182 F321, A403 WP321, A312 TP321 |
| 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 321 the usual specifications are A182 F321, A403 WP321, A312 TP321. 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 321 |
|---|---|
| Family | Austenitic stainless |
| UNS | S32100 |
| EN / W.Nr | 1.4541 X6CrNiTi18-10 |
| Basis spec | ASTM A240 |
| Density g/cm³ | 7.93 |
| Chemical composition, % | |
| C | 0.08 |
| Mn | 2.00 |
| P | 0.045 |
| S | 0.030 |
| Si | 0.75 |
| Cr | 17.0–19.0 |
| Ni | 9.0–12.0 |
| N | 0.10 |
| Ti | 5×(C+N)–0.70 |
| Mechanical properties (min) | |
| Tensile strength | 515 MPa (75 ksi) |
| Yield strength (0.2%) | 205 MPa (30 ksi) |
| Elongation | 40% |
| Hardness (max) | 217 HB |
| PREN (min, from spec) | 17.0 |
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 321?
S32100.
Which ASTM specifications cover Stainless 321?
A182 F321, A403 WP321, A312 TP321.
What is the density of Stainless 321?
About 7.93 g/cm³ (7930 kg/m³), used for weight calculations.
Last updated 2026-11-02