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EN 10269 Standard for Bolting Steels (Elevated-Temperature Fasteners)
EN 10269 is the European Norm that governs steels and nickel alloys for fasteners with specified elevated-temperature and low-temperature properties. The standard is the controlling spec for the 21CrMoV5-7 (Werkstoff 1.7709) Cr-Mo-V bolting steel and for the wider creep-resistant bolting family used in steam turbine casings, gas turbine compressor flanges, pressure vessels under VdTUV Wb 350, and refinery fired-heater flange studs. The current edition is EN 10269:2013 + A1:2024.
Scope of EN 10269
EN 10269 specifies technical delivery conditions for bars, wire rod, semi-finished products, forgings and finished fasteners (bolts, screws, studs, nuts, washers) intended for service at elevated temperature, low temperature, or both. The standard governs chemistry ranges, heat-treatment condition, mechanical-property floors at room temperature and at the design metal temperature, 100,000-hour stress-rupture envelope in Annex A, inspection categories to EN 10204, and product marking.
Grade Matrix Relevant to 21CrMoV5-7
| Grade | Werkstoff | Service envelope | Use case |
|---|---|---|---|
| 21CrMoV5-7 | 1.7709 | up to 550 deg C | Workhorse Cr-Mo-V Q+T bolting |
| 21CrMoV5-11 | 1.8070 | up to 550 deg C | Heavier-section variant of 5-7 |
| 24CrMoV5-5 | 1.7733 | up to 500 deg C | Lower-temp adjacent grade |
| 20CrMoVTiB4-10 (Durehete 1055) | 1.7729 | up to 568 deg C | Premium Ti+B microalloyed |
| 40CrMoV4-6 (Durehete 950) | 1.7711 | up to 540 deg C | Mid-tier ASTM A193 B16 cousin |
| 42CrMoV5-6 (Durehete 900) | 1.7733 family | up to 480 deg C | Lower-temp workhorse |
21CrMoV5-7 Chemistry to EN 10269
Detailed element-by-element ranges for 21CrMoV5-7 are on the dedicated chemical composition page. Headline: C 0.17 to 0.25, Cr 1.20 to 1.50, Mo 0.55 to 0.80, V 0.20 to 0.35 with vanadium-driven secondary hardening as the creep-resistance driver.
Mechanical-Property Floor (EN 10269)
Room-temperature 0.2 percent proof stress at least 550 MPa, tensile strength 700 to 850 MPa, elongation A5 at least 16 percent, Charpy V impact at least 63 J at 20 deg C. Elevated-temperature 0.2 percent proof at 500 deg C at least 450 MPa. Full table on the mechanical properties page.
Inspection Categories to EN 10204
EN 10269 references the inspection-document categories defined in EN 10204: type 2.1 declaration of compliance, type 2.2 test report, type 3.1 mill test certificate (issued by the manufacturer with heat-level traceability), and type 3.2 inspection certificate (witnessed by Lloyd's Register, DNV, BV, SGS or TUV). Type 3.1 is the TorqBolt default; type 3.2 is standard practice for turbine and pressure-vessel procurement.
Cross-References to Other Standards
EN 10269 cross-references are catalogued on the EN 10269 equivalents page. Headline mappings: ASTM A193 Grade B16 (closest US cousin to 21CrMoV5-7); AFNOR 20CDV5.7 (French); Polish PN 21HMF; DIN EN 10269 and BS EN 10269 (German and British national variants of the same European Norm).
Latest Revision: EN 10269:2013 + A1:2024
The 2024 amendment refreshes the elevated-temperature data tables in Annex A and the inspection cross-references to the latest EN 10204 edition. DIN EN 10269 and BS EN 10269 are national variants with the same technical content. EN 10278 is the companion standard for cold-drawn bright steel bars, which applies to drawn 21CrMoV5-7 bar stock.
21CrMoV5-7 Chemistry (Werkstoff 1.7709 Element Ranges)
21CrMoV5-7 (Werkstoff 1.7709) chemistry is fixed within a tight Cr-Mo-V Q+T window to EN 10269. Carbon at 0.17 to 0.25 percent gives the Q+T hardenability backbone without over-hardening for the secondary temper. Chromium at 1.20 to 1.50 percent provides through-thickness hardenability and stabilises the carbide network for creep. Molybdenum at 0.55 to 0.80 percent suppresses temper embrittlement and contributes to the secondary hardening peak. Vanadium at 0.20 to 0.35 percent drives the V4C3 precipitation during the 680 to 740 deg C temper that locks in the creep envelope. The chemistry window is shared with the AFNOR 20CDV5.7 (French) and Polish 21HMF designations.
| Element | Min % | Max % | Role |
|---|---|---|---|
| Carbon (C) | 0.17 | 0.25 | Q+T hardenability |
| Silicon (Si) | — | 0.40 | Deoxidation |
| Manganese (Mn) | 0.40 | 0.80 | Hardenability + solid-solution |
| Phosphorus (P) | — | 0.030 | Tramp limit for toughness |
| Sulphur (S) | — | 0.030 | Tramp limit |
| Chromium (Cr) | 1.20 | 1.50 | Hardenability + creep |
| Molybdenum (Mo) | 0.55 | 0.80 | Secondary hardening |
| Vanadium (V) | 0.20 | 0.35 | V4C3 carbide strengthening |
| Nickel (Ni) | — | 0.60 | Residual |
| Aluminium (Al) | — | 0.030 | Grain refinement |
Creep Performance at 500-550 deg C (EN 10269 Annex A)
The defining value-prop of 21CrMoV5-7 is the secondary-hardening creep envelope driven by V4C3 carbide precipitation. The fine V4C3 dispersion formed during the 680 to 740 deg C temper pins dislocation motion during long-time elevated-temperature service. The result is a 100,000-hour stress-rupture envelope to EN 10269 Annex A of approximately 340 MPa at 500 deg C, 290 MPa at 525 deg C, 260 MPa at 540 deg C, and 180 MPa at 550 deg C. Above 550 deg C the V4C3 coarsens faster than the design can tolerate; this is the boundary where the design must step up to Durehete 1055 (Alloy T41 / 1.7729) with Ti+B microalloying for grain-boundary pinning that extends the envelope to 568 deg C continuous service.
| Temperature | 100,000 h rupture stress | 1 percent creep strain at 100,000 h |
|---|---|---|
| 450 deg C | ~470 MPa | ~380 MPa |
| 500 deg C | ~340 MPa | ~280 MPa |
| 525 deg C | ~290 MPa | ~235 MPa |
| 540 deg C | ~260 MPa | ~210 MPa |
| 550 deg C | ~180 MPa | ~150 MPa |
Heat Treatment (Q+T Cycle)
The standard cycle for 21CrMoV5-7 is austenitisation at 880 to 940 deg C with hold time of 1 hour per 25 mm section, followed by oil quench. The temper is at 680 to 740 deg C for minimum 2 hours then air cool. The temper temperature is chosen to land on the secondary-hardening peak; below 660 deg C the V4C3 carbide precipitation is under-developed and long-term creep performance suffers; above 750 deg C the carbides over-coarsen and the room-temperature yield drops below the EN 10269 floor of 550 MPa. For heavily machined fastener blanks where dimensional stability matters, a stress relief at 50 deg C below the final temper is recommended after machining.
Welding Procedure (Matched Cr-Mo-V Filler + PWHT)
21CrMoV5-7 is welded with matched-composition Cr-Mo-V low-hydrogen filler (AWS A5.5 E9018-B3L for SMAW, AWS A5.28 ER90S-B3L for GTAW, AWS A5.23 EB3 for SAW) under preheat 200 to 300 deg C and diffusible-hydrogen cap of 5 ml per 100 g deposited. Post-weld heat treatment at 690 to 720 deg C for 1 hour per 25 mm joint thickness, minimum 2 hours, slow furnace cool to 300 deg C then air cool. The PWHT re-tempers the heat-affected zone and restores creep performance. Hardness traverse across weld plus HAZ plus parent metal verifies the PWHT achieved the intended tempering; HAZ hardness must not exceed 320 HBW.
Material Selection: 21CrMoV5-7 vs ASTM A193 B16 vs B7 vs Durehete 1055
21CrMoV5-7 sits between ASTM A193 Grade B7 (carbon-Mo only, no vanadium, capped at 450 deg C) and Durehete 1055 (Alloy T41 with Ti+B microalloying, 568 deg C envelope). Its direct US cousin is ASTM A193 Grade B16, with overlapping Cr-Mo-V chemistry and similar 540 deg C service envelope. Dual-certification to EN 10269 21CrMoV5-7 plus ASTM A193 B16 from the same heat lot is standard practice on cross-procurement projects.
| Grade | Chemistry | Max temp | When to specify |
|---|---|---|---|
| ASTM A193 B7 | Cr-Mo (no V) | 450 deg C | Lower-temp bolting where cost matters |
| 21CrMoV5-7 | Cr-Mo-V Q+T | 550 deg C | Workhorse mid-tier turbine + power + refinery |
| ASTM A193 B16 | Cr-Mo-V Q+T | 540 deg C | US dual-cert cousin |
| 21CrMoV5-11 (1.8070) | Cr-Mo-V Q+T higher Mo | 550 deg C | Heavier section (OD above 200 mm) |
| Durehete 1055 (Alloy T41 / 1.7729) | Cr-Mo-V-Ti-B | 568 deg C | HP turbine + supercritical + USC |
Frequently Asked Questions
Q. What does EN 10269 specify?
EN 10269 specifies the technical delivery conditions for steels and nickel alloys used in bolts, nuts, studs, screws and washers intended for service at elevated temperature, low temperature, or both.
Q. What is the latest revision of EN 10269?
EN 10269:2013 with Amendment A1:2024. The 2024 amendment refreshes the elevated-temperature data tables and the inspection category cross-references.
Q. Where does 21CrMoV5-7 sit within the EN 10269 grade matrix?
21CrMoV5-7 (Werkstoff 1.7709) is the workhorse mid-tier Cr-Mo-V Q+T bolting steel for service to 550 deg C. Sister grade 21CrMoV5-11 covers heavier sections; for service above 550 deg C the family steps up to Durehete 1055 (Alloy T41 / 1.7729).
Q. What is the ASTM equivalent of EN 10269?
The closest US analog is ASTM A193 for high-temperature bolting and ASTM A194 for matched nuts. Grade-level: 21CrMoV5-7 to ASTM A193 Grade B16.
Q. Do you supply EN 10269 material with type 3.2 certification?
Yes. Type 3.1 by default; type 3.2 with Lloyd's, DNV, BV, SGS or TUV witness on call-out and standard practice for turbine procurement.
Related Standards and Properties
Related standards: EN 10278 (cold-drawn bar) · VdTUV Wb 350 · ASTM A193 · EN 10269 Equivalents. Properties pages: Chemistry · Mechanicals · Heat Treatment · Hardness · Creep-Rupture. Back to the 21CrMoV5-7 Alloy Hub.
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