GB Standard 35CrMoNiV12-5 Seamless Steel Pipe Fatigue-Resistant, High-Pressure-Withstanding, Preferred for Marine/Mining Machinery Q+T Alloy Pipes
particularly in terms of high strength, high toughness, and fatigue resistance. It is widely used in manufacturing key mechanical parts that bear heavy loads, impacts, and alternating stresses.
I. Core Chemical Composition (Mass Fraction, Referring to GB/T 3077 Standard)
The properties of this steel grade are mainly determined by the following key alloying elements, and the content of each element must be controlled within a specific range:
| content |
C |
Si |
Mn |
P |
S |
Cr |
Ni |
Cu |
Mo |
V |
| Min. |
0.32 |
0.17 |
0.25 |
- |
- |
1.3 |
0.6 |
- |
0.2 |
0.1 |
| Max. |
0.42 |
0.37 |
0.5 |
0.03 |
0.03 |
1.7 |
0.9 |
0.25 |
0.3 |
0.25 |
Impact Energy (Akv, -40ºC): ≥39J, demonstrating excellent low-temperature toughness, making it suitable for cold environments or impact working conditions.
Due to its balanced performance of "high strength + high toughness", it is mainly used in manufacturing key parts with extremely high reliability requirements:
Construction Machinery: Crankshafts and connecting rods of large excavators and loaders.
Transmission Systems: High-speed gears and drive shafts of automobiles, ships, and machine tools.
Heavy-Duty Equipment: Heavy-load shafts and bolts of rolling mills and mining machinery.
Aerospace: Some small and medium-sized load-bearing structural components (derivative grades are selected when higher standards need to be met).
Precautions for Use
Heat Treatment Sensitivity: The quenching temperature (usually 850-880ºC) and tempering temperature (500-600ºC) must be strictly controlled; otherwise, performance fluctuations are likely to occur.
Weldability: Preheating (250-300ºC) is required before welding, and timely tempering should be conducted after welding to eliminate internal stress and prevent welding cracks.
Standard Differences: The corresponding grade relationships vary across different countries. For example, 40NiCrMo7 under the German DIN standard and 4340 under the American AISI standard have similar properties but slightly different compositions. Specific standards must be verified during material selection.
Notes on Technical Terms:
"Q+T" is translated as "quenching and tempering" (a common heat treatment process in metallurgy, combining quenching and high-temperature tempering to balance strength and toughness).
GB/T 3077 is the Chinese national standard for "Alloy Structural Steels", retained in its original form (common practice for international technical document translation to ensure traceability).
Symbols such as σb (tensile strength), σs (yield strength), and δ5 (elongation) follow international metallurgical notation conventions and remain unchanged.
2. Mechanical Properties (After Quenching + Tempering Treatment)
The mechanical properties of 25CrMnSi steel are mainly tested after heat treatment (quenching temperature: 880-920°C, tempering temperature: 540-600°C), which is the state for most practical applications.Property IndexStandard RequirementTensile Strength (σb)≥885 MPaYield Strength (σs)≥735 MPaElongation After Fracture (δ5)≥10%Reduction of Area (ψ)≥40%Impact Absorption Energy (Akv)≥47 J (at room temperature
High Tensile/Yield Strength: σb ≥885 MPa and σs ≥735 MPa enable it to withstand heavy loads, suitable for stress-bearing components like drive shafts and structural supports.
Good Toughness: δ5 ≥10% and Akv ≥47 J ensure the steel is not easy to fracture under impact or vibration, avoiding sudden failure of parts.Heat Treatment Dependence: The above properties are based on standard heat treatment; improper heat treatment may lead to performance degradation.Drive System Components: Used in manufacturing drive shafts, universal joint forks, or connecting rods that require high torque resistance.Suspension and Chassis Parts: Applied to high-stress chassis components, such as suspension links or stabilizer bars, to ensure structural stability.
Heavy-Duty Vehicle Parts: More commonly used in commercial vehicles (e.g., trucks, buses) or off-road vehicles, where components face stricter load and durability demands.
Mechanical Property Comparison
| Property |
35CrNiMoV |
AISI 4140 (Quenched + Tempered) |
|
| Tensile Strength |
≥1100 MPa |
≥1080 MPa (156.6 ksi) |
Significantly higher in 4140. |
| Yield Strength |
≥1200MPa |
≥930 MPa (134.9 ksi) |
Substantially higher. |
| Elongation (δ5) |
≥10% |
≥12% |
Better ductility. |
| Impact Energy (Akv) |
≥47 J |
≥63 J |
Higher toughness. |
Main Application Scenarios
Due to its balanced performance of "high strength + high toughness", it is mainly used in manufacturing key parts with extremely high reliability requirements:
Construction Machinery: Crankshafts and connecting rods of large excavators and loaders.
Transmission Systems: High-speed gears and drive shafts of automobiles, ships, and machine tools.
Heavy-Duty Equipment: Heavy-load shafts and bolts of rolling mills and mining machinery.
Aerospace: Some small and medium-sized load-bearing structural components (derivative grades are selected when higher standards need to be met).
IV. Precautions for Use
Heat Treatment Sensitivity: The quenching temperature (usually 850-880ºC) and tempering temperature (500-600ºC) must be strictly controlled; otherwise, performance fluctuations are likely to occur.
Weldability: Preheating (250-300ºC) is required before welding, and timely tempering should be conducted after welding to eliminate internal stress and prevent welding cracks.
Standard Differences: The corresponding grade relationships vary across different countries. For example, 40NiCrMo7 under the German DIN standard and 4340 under the American AISI standard have similar properties but slightly different compositions. Specific standards must be verified during material selection
Q1: Why choose us?
A: Our company, as an internationally experienced and professional supplier, has been engaged in steel business for more than ten years. We can provide a variety of steel products with high quality to our clients.
Q2: Can you provide OEM/ODM service?
A: Yes. Please feel free to contact us for more details.
Q3:What is your terms of payment?
A: 100% T/T advance.
30% T/T and balance against copy of documents.
30% T/T advance, balance L/C at sight.
Q4: Can we visit your factory?
A: Warmly welcome. Once we have your schedule, we will arrange the professional sales team to follow up your case.
Q5: Can you provide sample?
A: Yes. Sample is free for regular sizes, but the buyer needs to pay freight cost.
Q6: How long is your delivery time?
A: Regular lead time is 15 to 30 days after receiving deposit.
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