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- MERKBLATT AD 2000 W2/W7/W10
21CrMoV5-7 vs ASTM A193 Grade B7 (EN 10269 Cross-Reference)
21CrMoV5-7 (Werkstoff 1.7709) and ASTM A193 Grade B7 are two different bolting families. B7 is a Cr-Mo (no vanadium) Q+T alloy for service to ~450 deg C; 21CrMoV5-7 is a Cr-Mo-V Q+T alloy for service to 550 deg C with vanadium-driven secondary hardening. B7 is the cheaper choice below 450 deg C; 21CrMoV5-7 is the workhorse above.
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At a Glance
| 21CrMoV5-7 | ASTM A193 Grade B7 | |
|---|---|---|
| Controlling standard | EN 10269 | ASTM A193 / ASME SA-193 |
| Werkstoff / UNS | 1.7709 | G41400 |
| Chemistry family | Cr-Mo-V Q+T | Cr-Mo (AISI 4140 base) Q+T |
| Service envelope | up to 550 deg C | up to 450 deg C |
| Vanadium content | 0.20 to 0.35 percent | none |
Chemistry Comparison
| Element | 21CrMoV5-7 | ASTM A193 B7 |
|---|---|---|
| C | 0.17 to 0.25 | 0.37 to 0.49 |
| Cr | 1.20 to 1.50 | 0.75 to 1.20 |
| Mo | 0.55 to 0.80 | 0.15 to 0.25 |
| V | 0.20 to 0.35 | none |
Mechanical Comparison
| Property | 21CrMoV5-7 | ASTM A193 B7 |
|---|---|---|
| Tensile (Rm) | 700 to 850 MPa | 860 MPa minimum |
| 0.2 percent proof (RT) | ≥550 MPa | ≥725 MPa |
| Max service temp | 550 deg C | 450 deg C |
When to Specify Which
Specify 21CrMoV5-7 when service temperature exceeds 450 deg C and the design requires sustained creep performance. Specify ASTM A193 Grade B7 when service stays below 450 deg C and cost matters; B7 ships from torqbolt.com at a lower per-kg price point. For service in the 400 to 450 deg C window, designers often spec B7 for the lower cost; for cyclic-load joints at the same temperature, 21CrMoV5-7 holds preload through thermal cycling better.
Form Availability
Both grades supplied in round bar and the full bolting form-factor range: stud bolts, hex bolts, heavy hex bolts, tap studs, nuts, washers and threaded rod.
Frequently Asked Questions
Q. Can I substitute B7 for 21CrMoV5-7 to save cost?
Only below 450 deg C. Above 450 deg C the B7 carbon-Mo chemistry lacks vanadium, so secondary hardening from V4C3 precipitation is absent and the creep envelope drops sharply. The cost saving disappears in the first re-tightening cycle.
Q. Is 21CrMoV5-7 the same as ASTM A193 Grade B7?
No. Different chemistry family (Cr-Mo-V vs Cr-Mo no V), different service envelope (550 vs 450 deg C), different qualification. B7 is the workhorse cheaper grade for moderate temperature; 21CrMoV5-7 is the elevated-temperature step up.
Q. What is the chemistry difference in one line?
21CrMoV5-7 has vanadium (0.20 to 0.35 percent); B7 has none. The vanadium drives secondary hardening and is the reason 21CrMoV5-7 holds creep performance to 550 deg C while B7 caps at 450 deg C.
Q. Can you supply both grades dual-certified?
No. The chemistry windows do not overlap (different C, different Mo, no V in B7). Dual-cert requires both standards to be satisfied by the same heat, which the chemistry forbids. Order each grade separately.
Related Cross-References
More cross-references: vs ASTM A193 B16 · vs ASTM A193 B8 · vs 21CrMoV5-11 · vs 24CrMoV5-5 · vs Durehete 1055 · vs 20CDV5.7 (AFNOR) · vs 21HMF (Polish) · vs 42CrMo4. Back to the 21CrMoV5-7 Alloy Hub.
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