ASTM A182 F21 — Chemical Composition & Mechanical Properties
ASTM A182 F21 is a chrome-moly alloy steel grade for forged flanges & fittings (UNS K31545). It is also known as 3Cr-1Mo. This sheet summarises its chemical composition limits, minimum mechanical properties, heat treatment and typical service. Teshi Group manufactures flanges and fittings in this grade.
ASTM A182 F21 at a glance
| Specification | ASTM A182 F21 |
|---|---|
| Material family | Chrome-moly alloy steel |
| Product form | Forged flanges & fittings |
| UNS number | K31545 |
| Also known as | 3Cr-1Mo |
| Document | TG-MG-134 · Rev. 1 · October 2026 |
Typical service
3Cr-1Mo forgings for hydrogen and high-temperature service
Heat treatment
Annealed, normalised and tempered, or quenched and tempered
Chemical composition of ASTM A182 F21 (weight %)
Single values are maximums unless shown as a range or “min”.
Mechanical properties
| Tensile strength, min | 515 MPa |
|---|---|
| Yield strength (0.2 % offset), min | 310 MPa |
| Elongation, min | 20 % |
| Hardness | 156–207 HBW |
About chrome-moly alloy steel
Chrome-moly steels are low-alloy steels with 1–9 % chromium and 0.5–1 % molybdenum. Chromium gives oxidation and sulphidation resistance; molybdenum gives creep strength at high temperature. They are the standard choice for steam and hot hydrocarbon service above the carbon-steel range.
Reference information compiled from the published standard for convenience. It does not replace the current edition of the governing standard, which takes precedence. Verify critical dimensions and properties before design, purchase or fabrication. Teshi Engineers & Sales Promoters (P) Ltd accepts no liability for errors or omissions.
International equivalents of ASTM A182 F21
All equivalents| Standard system | Nearest equivalent grade |
|---|---|
| USA — ASTM / ASME | ASTM A182 F21 · ASME SA-182 F21 |
| USA — UNS | K31545 |
| Japan — JIS | SFVAF21A |
Equivalents are the nearest commonly cited grades. Chemistry, mechanical properties and testing differ between standards — compare them before substituting one for another.
Same alloy in other product forms
| Product form | Specification / grade |
|---|---|
| Seamless pipe | ASTM A335 P21 |
Standards for ASTM A182 F21
All material standardsFAQ
ASTM A182 F21: common questions
What is the minimum yield strength of ASTM A182 F21?
310 MPa, with a minimum tensile strength of 515 MPa.
What is the carbon content of ASTM A182 F21?
0.05–0.15 %.
How is ASTM A182 F21 heat treated?
Annealed, normalised and tempered, or quenched and tempered.
What is the JIS equivalent of ASTM A182 F21?
The nearest Japanese (JIS) equivalent is SFVAF21A.
Does Teshi Group supply ASTM A182 F21?
Teshi Group manufactures flanges and fittings in this grade. Send your size, rating and quantity to info@teshigroup.com for a quotation with EN 10204 3.1 certificates.
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