45CrNiMo1V is a chromium-nickel-molybdenum-vanadium alloy structural steel produced under Baosteel's internal standard BJTG07-009. It sits in the same family as AISI 4340 and the Chinese grade 40CrNiMoA, but it is not a simple renumbered copy. The vanadium addition and the tighter chemistry window give it a distinct hardenability and toughness profile, which is why it appears in demanding applications such as heavy-duty shafts, gears, and high-strength fasteners.
This article is written for overseas buyers and design engineers who need a practical comparison. All data below is based on a typical Baosteel mill test certificate. Actual values must be confirmed against the MTC for each heat.
What Is 45CrNiMo1V?
45CrNiMo1V is a low-alloy, high-hardenability steel. The "45" indicates a nominal carbon content of around 0.45%, though the actual range in BJTG07-009 is typically 0.36–0.44%. The Cr-Ni-Mo combination provides deep hardening, while the small vanadium addition refines grain size and improves toughness after tempering.
It is supplied in round bar, forged bar, and plate form. Common delivery conditions include hot-rolled, annealed, or quenched and tempered. Buyers should specify the condition explicitly, because the same grade can show very different properties depending on heat treatment.
Chemical Composition: 45CrNiMo1V vs 4340 vs 40CrNiMoA
A typical 45CrNiMo1V heat from Baosteel shows approximately:
| C | 0.38 | 0.38–0.43 | 0.37–0.44 |
| Si | 0.27 | 0.15–0.35 | 0.17–0.37 |
| Mn | 0.88 | 0.60–0.80 | 0.50–0.80 |
| P | 0.008 | ≤0.035 | ≤0.025 |
| S | 0.005 | ≤0.040 | ≤0.025 |
| Cr | 1.08 | 0.70–0.90 | 0.60–0.90 |
| Ni | 1.47 | 1.65–2.00 | 1.25–1.75 |
| Mo | 0.21 | 0.20–0.30 | 0.15–0.25 |
| Cu | 0.06 | ≤0.35 | ≤0.25 |
| V | 0.10 | - | - |
Compared with AISI 4340, the nickel content is slightly lower, the chromium is higher, and the vanadium addition is the main differentiator. Compared with 40CrNiMoA, the carbon and vanadium levels are on the higher side, which generally means higher strength potential but also greater sensitivity to heat treatment.
Mechanical Properties After Quenching and Tempering
In the quenched and tempered condition, a 110 mm round bar of 45CrNiMo1V typically achieves:
| Property | Typical Value |
|---|---|
| Tensile strength | ≥ 1,100 MPa |
| Yield strength | ≥ 1,030 MPa |
| Elongation | 11–12% |
| Impact energy | ≥ 47 J |
| Hardness | 236–306 HB |
These values are consistent with a medium-to-high strength alloy steel intended for dynamically loaded components. The combination of yield strength above 1,000 MPa and impact toughness near 50 J is the reason this grade is chosen over simpler 4140-type steels when section size is large or when fatigue life matters.
Heat Treatment and Hardenability Considerations
45CrNiMo1V is normally oil-quenched from around 850–870°C and tempered at 550–650°C, depending on the target strength. Because of its high hardenability, it can be through-hardened in sections up to roughly 100–150 mm, depending on the quench severity.
Two points matter for overseas buyers. First, the vanadium addition makes the steel less sensitive to overheating, but it does not eliminate the need for proper austenitizing temperature control. Second, the final properties are determined by the tempering temperature, not by the grade name alone. A certificate that states "45CrNiMo1V" without a heat treatment condition is incomplete.
Typical Applications
- Heavy-duty shafts and axles
- Gears and pinions for industrial drives
- High-strength bolts and studs
- Connecting rods and crankshafts
- Oil and gas tooling components
What to Check on the Mill Test Certificate
When reviewing an MTC for 45CrNiMo1V, verify:
- Heat number matches the marking on the bar
- Full chemistry includes V, Cu, and residual elements
- Mechanical properties include tensile, yield, elongation, and impact
- Heat treatment condition is stated
- Applicable standard is identified (BJTG07-009 or customer specification)
- Issue date and mill name are clear
Sichuan Liaofu Special Steel Trading Co., Ltd. supplies 45CrNiMo1V round bar sourced from Baosteel and other approved Chinese mills. We are a trader, not a mill, and every shipment includes the original mill MTC.
FAQ
Q: Is 45CrNiMo1V the same as 4340?
A: Not exactly. They are close equivalents in the Cr-Ni-Mo family, but 45CrNiMo1V contains vanadium and follows Baosteel's BJTG07-009 standard, which has tighter limits on P and S than commercial 4340. Always confirm the standard and heat treatment condition on the MTC before substituting.
Q: Can 45CrNiMo1V be used in place of 40CrNiMoA?
A: In most cases yes, because both are Cr-Ni-Mo structural steels with similar hardenability. However, 45CrNiMo1V typically has higher carbon and vanadium, so the quenched and tempered properties may be higher. Verify the required strength and impact values before substituting.
Q: What is the maximum section size for through-hardening?
A: It depends on the quench severity and the required properties. For oil quenching, 45CrNiMo1V can be through-hardened in sections up to roughly 100–150 mm. For larger sections, confirm the hardenability curve from the mill.
Q: Do you supply 45CrNiMo1V in the annealed condition?
A: Yes. Delivery condition depends on your manufacturing route. We can supply hot-rolled, annealed, or quenched and tempered material, with the condition stated on the mill MTC.
Q: Do you provide the original mill MTC?
A: Yes. Every shipment includes the original Baosteel or mill-issued MTC with full heat traceability.
Q: Can you cut 45CrNiMo1V round bar to length?
A: Yes. We offer cut-to-size service, and each cut piece retains its heat number marking and matches the original MTC.
Q: Are you a steel mill or a trading company?
A: We are a trading company. Sichuan Liaofu does not melt steel and does not operate a laboratory. All data comes from the producing mill's original documentation.