GB/T 8162 40Cr Seamless Steel Pipe Material
GB/T 8162 40Cr Seamless Steel Pipe - Alloy Structural Steel Tube for Heavy-Duty Shafts & Machinery
40Cr is a Chinese alloy structural steel supplied as seamless pipes under GB/T 8162. After quenching and tempering, it provides high strength, good toughness, and excellent wear resistance. Widely used for mechanical components such as shafts, gears, and connecting rods.
Hot rolling, cold drawing, hot expansion, forging, machining, welding (with preheating), heat treatment (quenching & tempering, normalizing, annealing)
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GB/T 8162 40Cr Seamless Steel Pipe Introduction
40Cr seamless steel pipe covered by GB/T 8162 is a medium-carbon chromium alloy structural steel intended for structural applications. The pipe can be supplied in hot-rolled, normalized, annealed, or quenched-tempered condition. With proper heat treatment, it achieves a superior combination of high tensile strength (>980 MPa), yield strength (>785 MPa), and moderate toughness. The chromium addition enhances hardenability and wear resistance, making it suitable for manufacturing shafts, gears, bolts, and other machine parts. Good machinability and weldability can be realized with suitable preheating and post-weld treatment. It is widely adopted in the automotive, engineering machinery, and heavy equipment sectors.
GB/T 8162 40Cr Seamless Steel Pipe Chemical Composition
Chemical composition of 40Cr according to GB/T 3077 (alloy structural steel) as referenced by GB/T 8162. Values are based on ladle analysis. Small permissible deviations for product analysis may apply.
- Carbon (C): provides base strength and hardenability.
- Chromium (Cr): improves hardenability, wear resistance, and corrosion resistance.
- Manganese (Mn): deoxidizer, enhances strength and hardenability.
- Silicon (Si): deoxidizer, increases strength.
| Element | Specified Value (%) | Remarks |
|---|---|---|
| C | 0.37 - 0.44 | |
| Si | 0.17 - 0.37 | |
| Mn | 0.50 - 0.80 | |
| Cr | 0.80 - 1.10 | |
| P | ≤ 0.035 | |
| S | ≤ 0.035 | |
| Ni | ≤ 0.30 | Residual element |
| Cu | ≤ 0.30 | Residual element |
| Mo | ≤ 0.10 | Residual element (not intentionally added) |
| V | ≤ 0.05 | Residual element |
GB/T 8162 40Cr Seamless Steel Pipe Physical & Thermal Properties
Physical properties of 40Cr steel at room temperature and elevated temperatures, based on published engineering data for similar chromium steel grades. These values are typical and may vary depending on heat treatment and exact composition.
- Density, modulus, and Poisson's ratio are fundamental for design calculations.
- Thermal expansion and conductivity influence welding and thermal stress analysis.
- Electrical resistivity is important for certain sensor or heating applications.
| Property | Typical Value | Unit | Condition / Temperature |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20°C |
| Modulus of Elasticity (E) | 206 | GPa | 20°C, static tensile |
| Shear Modulus (G) | 79.4 | GPa | 20°C, calculated from E and ν |
| Poisson's Ratio (ν) | 0.30 | - | 20°C |
| Thermal Expansion Coefficient (α) | 11.5 | ×10⁻⁶/K | 20-100°C |
| Thermal Expansion Coefficient (α) | 12.4 | ×10⁻⁶/K | 20-200°C |
| Thermal Expansion Coefficient (α) | 13.2 | ×10⁻⁶/K | 20-400°C |
| Thermal Conductivity (λ) | 44 | W/(m·K) | 100°C |
| Thermal Conductivity (λ) | 39 | W/(m·K) | 300°C |
| Specific Heat Capacity (cp) | 460 | J/(kg·K) | 20-100°C |
| Electrical Resistivity (ρe) | 0.23 | ×10⁻⁶ Ω·m | 20°C |
GB/T 8162 40Cr Seamless Steel Pipe Mechanical Properties
Mechanical properties for 40Cr seamless pipe in the quenched and tempered condition, as per GB/T 8162 (for wall thickness ≤ 16 mm). Properties may vary for larger sections. Impact test values are for standard Charpy V-notch specimens at room temperature.
- High tensile strength and yield strength after proper heat treatment.
- Good ductility indicated by elongation.
- Adequate impact toughness essential for dynamic loading.
| Property | Required Value | Unit | Test Condition |
|---|---|---|---|
| Tensile Strength (Rm) | ≥ 980 | MPa | Room temperature, round bar specimen from pipe |
| Yield Strength (ReL or Rp0.2) | ≥ 785 | MPa | Room temperature, 0.2% offset |
| Elongation (A) | ≥ 9 | % | Longitudinal, gauge length L0=5.65√S0 |
| Charpy Impact Energy (KV2) | ≥ 47 | J | Room temperature (20°C), V-notch, longitudinal |
| Brinell Hardness (HBW) | ≤ 229 (annealed) | - | Supply condition: annealed; for QT, typically 290~340 HBW |
| Bend Test (Bend Diameter) | Not specified in QT condition | - | Usually not required for QT pipes |
GB/T 8162 40Cr Seamless Steel Pipe Fully Equivalent International Standards and Substitutable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| China | GB/T 3077 / GB/T 8162 | 40Cr | Original standard grade, QT condition |
| USA | ASTM A29/A29M | 5140 | AISI/SAE grade; similar chemistry, QT mechanical properties comparable |
| Japan | JIS G4104 | SCr440 | Equivalent chromium steel; often supplied as bar or tube |
| Germany | DIN 17200 / DIN EN 10297-1 | 41Cr4 (1.7035) | Very close chemistry; for machinery tubes EN 10297-1 grade 41Cr4 |
| Great Britain | BS 970-1 | 530A40 | Comparable medium carbon Cr steel |
| International | ISO 683-1 | 41Cr4 | Standard ISO alloy steel; identical intent |
| France | NF A35-551 | 41Cr4 | AFNOR designation, fully interchangeable |
GB/T 8162 40Cr Seamless Steel Pipe Application Introduction
40Cr seamless pipe is a versatile alloy structural steel used where high strength and toughness are required after quenching and tempering. The tubular shape offers weight savings and torsional rigidity, making it ideal for mechanical transmissions, hydraulic cylinders, and hollow shafts. Machinability is good in the annealed or QT condition; welding requires preheating (200-300°C) and post-weld stress relief to avoid cracking. Typical heat treatment: quench from 850°C in oil, temper at 500-650°C to reach desired strength/hardness combination.
Product Applications: Propeller shafts, axle shafts, half-shafts, Steering knuckles and spindles, Hydraulic cylinder tubes and piston rods, Gear blanks and transmission parts, High-strength bolt and stud assemblies, Roller and conveyor system rollers, Drill rods and mining machinery components
Processed into products: Hollow transmission shafts, Piston rods and cylinder liners, Machine tool spindles and quills, Torque tubes and drive tubes, Locomotive axle tubes, Offshore platform structural tubulars (if qualified), Flanged pipe for structural frame connections
Application industries: Automotive & Commercial Vehicles, Engineering Machinery & Heavy Equipment, Mining & Construction, Machine Tool Manufacturing, Energy (Oil & Gas, Wind Power), Railway & Transportation
GB/T 8162 40Cr Seamless Steel Pipe Similar/Alternative Materials with Close Performance
| Country/Region | Standard | Grade | Analysis / Remarks |
|---|---|---|---|
| China | GB/T 3077 | 40MnB | Boron-treated alternative, similar hardenability, can replace 40Cr after QT, but lower Cr content and often cheaper |
| China | GB/T 3077 | 35CrMo | Mo-added version; better temper resistance and high-temperature strength, suitable for larger sections or more demanding service |
| USA | ASTM A29 | 5150 | Higher carbon and chromium; used for higher strength requirements, slightly lower ductility |
| Japan | JIS G4104 | SCr435 | Slightly lower carbon; provides higher toughness with slightly reduced strength, good for parts requiring extra ductility |
| Germany | DIN 17200 | 48CrMo4 (1.7225) | Mo-bearing grade; preferred in larger diameters for improved through-hardening and toughness |
Notes:
- 40Cr seamless pipe can be flared, flattened, or bent according to end-use requirements. The supplier should test the specified degree of deformation as agreed.
- Non-destructive testing (ultrasonic or eddy current) may be performed per GB/T 5777 or customer specification.
- For welded structures, tempering after welding is strongly recommended to relieve residual stress and restore toughness in the heat-affected zone.
- Surface quality and dimensional tolerances should conform to GB/T 8162 advanced specification or as agreed.
- When replacement with 40MnB is considered, consult with the heat treatment specialist due to different quenching sensitivity.
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