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 Chemical Composition (EN 10269 / Werkstoff 1.7709)
The chemistry of 21CrMoV5-7 (Werkstoff 1.7709) is fixed by EN 10269 within a tight Cr-Mo-V Q+T window. The chemistry is the controlling input for the secondary-hardening behaviour during the temper at 680 to 740 deg C and the resulting creep-rupture performance at 500 to 550 deg C metal temperature. Each element is bounded for a specific metallurgical purpose.
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Element Ranges (EN 10269)
| Element | Min % | Max % | Metallurgical role |
|---|---|---|---|
| Carbon (C) | 0.17 | 0.25 | Q+T hardenability backbone; supports V4C3 secondary hardening |
| Silicon (Si) | — | 0.40 | Deoxidation residual; slight solid-solution strengthening |
| Manganese (Mn) | 0.40 | 0.80 | Hardenability through CCT shift; solid-solution strengthening |
| Phosphorus (P) | — | 0.030 | Tramp limit for impact toughness and transverse ductility |
| Sulphur (S) | — | 0.030 | Tramp limit; modified MnS shape control via Ca treatment optional |
| Chromium (Cr) | 1.20 | 1.50 | Through-thickness hardenability and creep resistance |
| Molybdenum (Mo) | 0.55 | 0.80 | Secondary hardening with V; temper-embrittlement resistance |
| Vanadium (V) | 0.20 | 0.35 | Drives V4C3 precipitation at 680 to 740 deg C temper |
| Nickel (Ni) | — | 0.60 | Residual; toughness contribution at low temperature |
| Aluminium (Al) | — | 0.030 | Grain refinement via AlN precipitation; deoxidation |
| Copper (Cu) | — | 0.30 | Residual limit |
| Iron (Fe) | balance | Matrix | |
PMI Verification
Positive material identification by handheld XRF or OES is supplied on call-out per stud or per heat-lot batch. PMI report includes Cr, Mo, V, Mn, Ni, Cu and Fe with tolerance pass/fail against the EN 10269 21CrMoV5-7 window. Carbon, sulphur and phosphorus are reported from the mill chemistry on the EN 10204 type 3.1 or 3.2 certificate (XRF cannot quantify light elements).
Chemistry vs Neighbouring Grades
| Element | 21CrMoV5-7 | 21CrMoV5-11 | ASTM A193 B16 | Durehete 1055 (1.7729) |
|---|---|---|---|---|
| C | 0.17 to 0.25 | 0.17 to 0.25 | 0.36 to 0.47 | 0.17 to 0.24 |
| Cr | 1.20 to 1.50 | 1.20 to 1.50 | 0.80 to 1.15 | 0.80 to 1.20 |
| Mo | 0.55 to 0.80 | 0.90 to 1.10 | 0.50 to 0.65 | 0.55 to 0.75 |
| V | 0.20 to 0.35 | 0.25 to 0.35 | 0.25 to 0.35 | 0.20 to 0.40 |
| Ti | — | — | — | 0.04 to 0.10 |
| B | — | — | — | 0.0010 to 0.0050 |
Heat-Lot Traceability
Every 21CrMoV5-7 stock item ships with a heat number that ties back to the melt-shop pour record. The EN 10204 type 3.1 certificate carries the full chemistry, ladle position, deoxidation practice, and any PMI confirmation. For type 3.2 certification, a third-party witness (Lloyd's Register, DNV, BV, SGS, TUV) verifies the heat-lot identity match between bar stock, machined fastener and shipped certificate.
Frequently Asked Questions
Q. What is the carbon content of 21CrMoV5-7?
0.17 to 0.25 percent. The carbon range is set low enough to allow good through-thickness hardenability in the Q+T cycle while keeping carbide coarsening under control during the secondary-hardening temper.
Q. Why is vanadium critical in 21CrMoV5-7?
Vanadium (0.20 to 0.35 percent) drives the secondary-hardening peak through V4C3 carbide precipitation during tempering. The fine V4C3 dispersion is what gives the grade its long-time creep-rupture performance.
Q. What is the role of chromium in the chemistry?
Chromium (1.20 to 1.50 percent) provides through-thickness hardenability and stabilises the carbide network for creep resistance.
Q. Are the sulphur and phosphorus limits tighter than ASTM A193 B16?
Yes. EN 10269 caps S and P at 0.030 percent for 21CrMoV5-7. B16 caps S at 0.040 percent and P at 0.035 percent. Tighter limits reflect the higher impact-toughness target.
Related Properties Pages
Drill into 21CrMoV5-7 properties: Mechanical Properties · Heat Treatment (Q+T Cycle) · Elevated-Temperature Properties · Hardness · Creep-Rupture · Welding Procedure · Machinability. Standards: EN 10269 · vs ASTM A193 B16. Back to the 21CrMoV5-7 Alloy Hub.
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