Chrome-moly F22 / P22 (UNS K21590)
Chrome-moly F22 / P22 (UNS K21590) — 2¼Cr-1Mo for higher-temperature power and refinery lines.
| UNS number | K21590 |
| Material family | Alloy steel |
| Product specifications | ASTM A182 F22, A234 WP22, A335 P22 |
| Density (typical) | 7.85 g/cm³ (7850 kg/m³) |
| Weight of 6" Sch 40 pipe | 28.26 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 Chrome-moly F22 / P22 the usual specifications are ASTM A182 F22, A234 WP22, A335 P22. 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 | Alloy steel F22 Cl 3 |
|---|---|
| Family | Alloy steel |
| UNS | K21590 |
| EN / W.Nr | 1.7380 10CrMo9-10 |
| Basis spec | ASTM A182 |
| Density g/cm³ | 7.85 |
| Chemical composition, % | |
| C | 0.05–0.15 |
| Mn | 0.30–0.60 |
| P | 0.040 |
| S | 0.040 |
| Si | 0.50 |
| Cr | 2.00–2.50 |
| Mo | 0.87–1.13 |
| Mechanical properties (min) | |
| Tensile strength | 515 MPa (75 ksi) |
| Yield strength (0.2%) | 310 MPa (45 ksi) |
| Elongation | 20% |
| Hardness (max) | 207 HB |
| PREN (min, from spec) | – |
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 Chrome-moly F22 / P22?
K21590.
Which ASTM specifications cover Chrome-moly F22 / P22?
ASTM A182 F22, A234 WP22, A335 P22.
What is the density of Chrome-moly F22 / P22?
About 7.85 g/cm³ (7850 kg/m³), used for weight calculations.
Last updated 2026-11-02