4140 | 42CrMo4 | 42CrMo Steel Bar
4140 | 42CrMo4 | 42CrMo Steel Bar
4140 bar is an alloy steel known as AISI/SAE 4140, widely used in the US. The “4140” indicates its composition and standard. It offers high strength, toughness, and wear resistance. Commonly used in the production of gears, shafts, and machinery parts, 4140 steel can be annealed, normalized, or quenched and tempered.
Description
What is 4140 Steel Bar？
4140 steel bar, composed of 98% iron, 0.40% carbon, and alloying elements like chromium, molybdenum, and manganese, is a high-strength alloy steel. Known for toughness and wear resistance, it is hot-rolled and used in gears, shafts, and machinery parts. It can be annealed, normalized, or quenched and tempered. Make it widely used in automotive, aerospace, oil and gas, and construction industries.Characteristics of 4140 Steel Bar
4140 steel bar exhibits a fine-grained microstructure that enhances its mechanical properties. It can be heat-treated to achieve varying levels of hardness and strength. The presence of chromium and molybdenum improves its corrosion resistance and high-temperature performance, making it suitable for a wide range of applications in harsh environments. The advantages of 4140 steel include its durability, as the high strength and toughness ensure long-lasting performance in demanding applications, reducing the frequency of replacements and maintenance. Its excellent wear resistance extends the lifespan of parts made from 4140 steel, making it cost-effective for heavy-duty uses. Additionally, the ability to be annealed, normalized, or quenched and tempered allows for customization of mechanical properties to suit specific application needs. However, there are disadvantages to consider. The high hardness and strength of 4140 steel bar can make it challenging to machine, requiring specialized tools and techniques. Additionally, higher material and processing costs compared to lower-strength steels can be a consideration for budget-sensitive projects. For easier machining, consider using 1018 steel.Chemical Compositions
| Element | Composition |
|---|---|
| Carbon (C) | 0.38-0.43% |
| Manganese (Mn) | 0.75-1.00% |
| Silicon (Si) | 0.15-0.35% |
| Chromium (Cr) | 0.80-1.10% |
| Molybdenum (Mo) | 0.15-0.25% |
| Phosphorus (P) | 0.035% max |
| Sulfur (S) | 0.040% max |
Physical Properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.85 g/cm³ | 0.284 lb/in³ |
| Melting Point | 1425-1460°C | 2597-2660°F |
| Thermal Conductivity | 42.7 W/m·K | 24.7 BTU·ft/h·°F |
| Electrical Resistivity | 0.24 µΩ·m | 0.24 µΩ·m |
| Specific Heat Capacity | 460 J/kg·K | 0.11 BTU/lb·°F |
| Thermal Expansion Coefficient | 11.1 µm/m·K | 6.17 µin/in·°F |
| Elastic Modulus | 210 GPa | 30.5 Msi |
Mechanical Properties
| Property | Metric | Imperial |
|---|---|---|
| Tensile Strength (Rm) | 655-1170 MPa | 95-170 ksi |
| Yield Strength (Rp0.2) | 415-950 MPa | 60-138 ksi |
| Brinell Hardness (HBW) | 197-241 HBW | 197-241 HBW |
| Rockwell Hardness (HRC) | 22-32 HRC | 22-32 HRC |
| Vickers Hardness (HV) | 207-248 HV | 207-248 HV |
| Elongation (A) | 17-30% | 17-30% |
| Elastic Modulus | 190-210 GPa | 27.6-30.5 Msi |
QT Properties of of 4140 Steel bar
| Property | Metric | Imperial |
|---|---|---|
| Tensile Strength (Rm) | 930-1080 MPa | 135-157 ksi |
| Yield Strength (Rp0.2) | 780-930 MPa | 113-135 ksi |
| Impact Toughness (KV/Ku) | ≥ 39 J | ≥ 28.8 ft-lb |
| Elongation (A) | ≥ 12% | ≥ 12% |
| Reduction in Area (Z) | ≥ 45% | ≥ 45% |
| Brinell Hardness (HBW) | 241-285 HBW | 241-285 HBW |
Industries & Applications
| Industry | Applications |
|---|---|
| Automotive Industry | Crankshafts, camshafts, and transmission gears |
| Oil and Gas Industry | Drill collars, stabilizer bars, and downhole tool shafts |
| Construction Industry | Anchor bolts, tie rods, and heavy-duty support shafts |
| Machinery Manufacturing | Spindles, rollers, and drive shafts |
| Aerospace Industry | Landing gear struts, engine shafts, and structural support rods |
| Mining Industry | Excavator teeth, crusher jaws, and screening components |
| Agricultural Equipment | Plowshares, harrow discs, and tractor parts |
Machining
4140 Heat Treatment
- Solution Treatment: Heat to 840-880°C, hold, then rapidly cool (usually in water or oil).
- Aging Treatment: Heat at 150-200°C for an extended period.
- Quenching: Heat to 850-880°C, then rapidly cool (usually in oil).
- Tempering: Reheat quenched steel to 540-680°C, then cool.
- Normalizing: Heat to 870-900°C, then air cool.
- Annealing: Heat to 680-720°C, hold, then slowly cool in the furnace.
4140 Surface Finish
- Surface Hardening: Includes flame and induction hardening.
- Carburizing: Heat in a carbon-rich environment at high temperature.
- Nitriding: Heat in a nitrogen or ammonia atmosphere.
- Carbonitriding: Similar to carburizing but with nitrogen addition.
- Electroplating: Electrochemically deposit a metal layer (e.g., chromium, nickel).
- Thermal Spraying: Apply a high-hardness, wear-resistant coating.
Custom surface treatment requirements can be accommodated upon request.
Disclaimer
The above heat treatment instructions and surface finish processing methods for 4140 are provided for informational purposes only. Actual results may vary based on the specific conditions and equipment used. It is recommended to perform testing and consult with a metallurgical expert or the material supplier to ensure the processes are suitable for your specific application. The user assumes all risks and liability for the use of this information.
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