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21CrMoV5-7 vs 42CrMo4 (Werkstoff 1.7225 / AISI 4140) (EN 10269 Cross-Reference)
21CrMoV5-7 (Werkstoff 1.7709) and 42CrMo4 (Werkstoff 1.7225 / AISI 4140) are different bolting grades. 42CrMo4 is the workhorse Cr-Mo Q+T low-alloy with no vanadium; 21CrMoV5-7 adds vanadium for secondary hardening and elevated-temperature creep performance. 42CrMo4 is the cheaper grade for ambient and moderate-temperature service; 21CrMoV5-7 is the step up for service above 450 deg C.
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At a Glance
| 21CrMoV5-7 | 42CrMo4 (AISI 4140) | |
|---|---|---|
| Werkstoff | 1.7709 | 1.7225 |
| Standard | EN 10269 (elevated-temp bolting) | EN 10083-3 (Q+T structural) |
| Service envelope | up to 550 deg C | up to 450 deg C |
| Vanadium | 0.20 to 0.35 percent | none |
| Use case | Elevated-temperature bolting | Workhorse Q+T structural and ambient bolting |
Chemistry Comparison
| Element | 21CrMoV5-7 | 42CrMo4 |
|---|---|---|
| C | 0.17 to 0.25 | 0.38 to 0.45 |
| Cr | 1.20 to 1.50 | 0.90 to 1.20 |
| Mo | 0.55 to 0.80 | 0.15 to 0.30 |
| V | 0.20 to 0.35 | none |
Mechanical Comparison
| Property | 21CrMoV5-7 | 42CrMo4 (Q+T) |
|---|---|---|
| Tensile (Rm) | 700 to 850 MPa | 900 to 1100 MPa |
| 0.2 percent proof (RT) | ≥550 MPa | ≥650 MPa |
| Max service temp | 550 deg C | 450 deg C |
When to Specify Which
Specify 21CrMoV5-7 for elevated-temperature service (450 to 550 deg C) where vanadium-driven secondary hardening sustains creep performance. Specify 42CrMo4 for ambient and moderate-temperature structural bolting, gear shafts, automotive crankshafts and pump shafts where the higher room-temperature tensile is the design driver and temperature is below 450 deg C.
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. Is 42CrMo4 a bolting steel?
42CrMo4 is a general Q+T structural alloy used for gear shafts, crankshafts, pump shafts, axles and bolting up to 450 deg C. For elevated-temperature bolting above 450 deg C the chemistry lacks vanadium and the design must step up to 21CrMoV5-7.
Q. Can I substitute 42CrMo4 for 21CrMoV5-7 on a turbine flange?
No. 42CrMo4 service envelope caps at 450 deg C. Steam-turbine LP casing flanges already see 200 to 380 deg C; IP and HP exceed 450 deg C. Substituting 42CrMo4 for 21CrMoV5-7 on a turbine bolt risks creep relaxation in service.
Q. What is the AISI equivalent of 42CrMo4?
AISI 4140 / SAE 4140. The chemistry windows are essentially identical: C 0.38 to 0.45, Cr 0.90 to 1.20, Mo 0.15 to 0.30. Dual-cert to 42CrMo4 / AISI 4140 on call-out.
Q. Where does 42CrMo4 appear in EN 10269?
42CrMo4 (1.7225) is listed in EN 10269 as the carbon-Mo-only base grade for moderate-temperature bolting up to 450 deg C. The 21CrMoV5-7, 21CrMoV5-11 and 24CrMoV5-5 family build on the 42CrMo4 chemistry by adding vanadium for elevated-temperature service.
Related Cross-References
More cross-references: vs ASTM A193 B16 · vs ASTM A193 B7 · vs ASTM A193 B8 · vs 21CrMoV5-11 · vs 24CrMoV5-5 · vs Durehete 1055 · vs 20CDV5.7 (AFNOR) · vs 21HMF (Polish). Back to the 21CrMoV5-7 Alloy Hub.
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