Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
21CrMoV5-7 Round Bar (EN 10269 / 1.7709) Cr-Mo-V Q+T Bolting
21CrMoV5-7 round bar is the raw stock from which all 21CrMoV5-7 fasteners are machined. Supplied in the quenched-and-tempered condition to EN 10269 and (for cold-drawn bright tolerance) to EN 10278, in diameters from OD 16 to 300 mm with EN 10204 type 3.1 by default.
Round Bar Designs and Variants
Two finish grades: hot-rolled black bar with mill scale (OD 50 to 300 mm) for forging blanks and large-diameter bolt blanks; cold-drawn bright bar to EN 10278 h9 / h10 tolerance class (OD 16 to 100 mm) for direct machining without skin removal. Peeled-and-polished bar (h11) supplied on call-out.
Size Range
| Form | Diameter range | Tolerance |
|---|---|---|
| Hot-rolled black | OD 50 to 300 mm | EN 10060 / DIN 1013 |
| Cold-drawn bright (h9/h10) | OD 16 to 100 mm | EN 10278 h9/h10 |
| Peeled-and-polished (h11) | OD 25 to 250 mm | EN 10278 h11 |
| Forged round (annealed) | OD 200 to 800 mm | per project drawing |
Mechanical Properties (Q+T, EN 10269)
| Property | Value | Condition |
|---|---|---|
| Tensile (Rm) | 700 to 850 MPa | RT, Q+T |
| 0.2 percent proof stress (Rp0.2) | ≥550 MPa | RT, Q+T |
| Elongation A5 | ≥16 percent | RT, longitudinal |
| Charpy V impact (KV) | ≥63 J | 20 deg C |
| 0.2 percent proof at 500 deg C | ≥450 MPa | elevated-temp |
| Hardness | 210 to 250 HBW | Q+T |
Standards Anchor
21CrMoV5-7 round bar is supplied to EN 10269 for chemistry, mechanicals and inspection. Cold-drawn bright bar additionally to EN 10278 for dimensional tolerance. Pressure-vessel parallel approval to VdTUV Wb 350. US dual-certification to ASTM A193 Grade B16 on call-out.
Companion Hardware
Matched-grade Cr-Mo-V companions ship from the same heat lot on call-out: 21CrMoV5-7 nuts, washers, threaded rod, stud bolts and round bar.
Applications
Round bar is the parent stock for the full bolting form-factor range: stud bolts, hex bolts, heavy hex bolts, tap studs, body-bound studs, anchor bolts, threaded rod and forged blanks for fasteners above OD 200 mm.
Inspection Documentation
Default delivery is EN 10204 type 3.1 mill test certificate with heat number, melt-shop pour record, chemistry to EN 10269 21CrMoV5-7, room-temperature tensile and 0.2 percent proof stress, elevated-temperature 0.2 percent proof at the design temperature, Charpy V impact at 20 deg C, hardness, full Q+T cycle chart and dimensional report tied to the heat lot. Type 3.2 with Lloyd's Register, DNV, BV, SGS or TUV witness inspection on call-out and standard practice on turbine and pressure-vessel procurement.
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 diameter range do you stock 21CrMoV5-7 round bar in?
Hot-rolled OD 50 to 300 mm in stock; cold-drawn bright OD 16 to 100 mm to EN 10278 h9/h10; peeled-and-polished OD 25 to 250 mm on call-out; forged round OD up to 800 mm on project order.
Q. Is the round bar supplied in Q+T or annealed condition?
Default delivery is quenched and tempered (Q+T) to EN 10269 mechanical-property floors. Annealed bar for further heat treatment by the fastener manufacturer is supplied on call-out.
Q. What surface finish tolerance can I expect on cold-drawn bright bar?
EN 10278 tolerance class h9 (closer) or h10 (standard) on diameter. Surface roughness Ra typically 1.6 to 3.2 micrometre. h11 peeled-and-polished on call-out for direct-machine bolt blanks.
Q. Do you supply round bar with EN 10204 type 3.2 certification?
Yes. Type 3.1 by default with full chemistry, Q+T cycle, mechanicals, hardness and dimensional report. Type 3.2 with Lloyd's Register, DNV, BV, SGS or TUV witness on call-out and standard for pressure-vessel and turbine procurement.
Related 21CrMoV5-7 Form Factors
Browse the full 21CrMoV5-7 form-factor range: Stud Bolts · Hex Bolts · Heavy Hex Bolts · Tap Studs · Body-Bound Studs · Anchor Bolts · U-Bolts · Threaded Rod · Nuts · Washers · Forgings. Back to the 21CrMoV5-7 Alloy Hub.
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