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AISI 4140 Alloy Steel Pipe
What Is 4140 Alloy Steel?
AISI 4140 is a low-alloy steel containing chromium and molybdenum as strengthening agents. It is known for its good balance of strength, toughness, and wear resistance, making it suitable for a variety of applications.
How Is 4140 Alloy Steel Made?
4140 alloy steel is produced through the following steps:
- Melting: The raw materials (iron ore, chromium, molybdenum, and carbon) are melted in an electric arc or basic oxygen furnace.
- Refining: The molten steel is refined to remove impurities and achieve the desired chemical composition.
- Casting: The refined steel is cast into billets or blooms.
- Hot Rolling: The cast steel is hot-rolled into desired shapes and sizes, such as pipes.
- Heat Treatment: The steel undergoes heat treatment processes such as annealing, quenching, and tempering to enhance its mechanical properties.
What Are the Thermal Properties of 4140 Alloy Steel?
- Thermal Conductivity: Approximately 42.6 W/m·K at 23°C (73°F)
- Specific Heat: 477 J/kg·K at 23°C (73°F)
- Coefficient of Thermal Expansion: 12.3 µm/m·K from 20°C to 100°C (68°F to 212°F)
What Is the Carbon Content of 4140 Alloy Steel?
The carbon content of 4140 alloy steel is typically between 0.38% and 0.43%.
What Is 4140 Alloy Steel Used For?
4140 alloy steel is used in various applications, including:
- Automotive: Gears, shafts, and crankshafts
- Oil and Gas: Drill collars and tool joints
- Machinery: Spindles and couplings
- Construction: Structural components
- Tooling: Dies and molds
Machinability Rating of 4140 Alloy Steel
The machinability rating of 4140 alloy steel is around 66% of B1112 steel, making it moderately machinable with suitable equipment and techniques.
What Are the Properties of 4140 Alloy Steel?
- Tensile Strength: 655-895 MPa
- Yield Strength: 415 MPa
- Elongation: 20% in 50 mm
- Hardness: 197-237 HB (Brinell hardness)
- Impact Strength: Good toughness, even in hardened conditions
What Is the Chemical Composition of 4140 Alloy Steel?
- Carbon (C): 0.38-0.43%
- Manganese (Mn): 0.75-1.00%
- Phosphorus (P): ≤ 0.035%
- Sulfur (S): ≤ 0.040%
- Silicon (Si): 0.15-0.35%
- Chromium (Cr): 0.80-1.10%
- Molybdenum (Mo): 0.15-0.25%
What Are the Common Forms of 4140 Alloy Steel Material?
4140 alloy steel is available in various forms, including:
- Bars: Round, square, and flat bars
- Sheets and Plates: Various thicknesses
- Pipes and Tubes: Seamless and welded
- Forgings: Custom shapes and sizes
What Are Equivalents of 4140 Alloy Steel?
4140 alloy steel has several international equivalents, such as:
- EN 1.7225 (42CrMo4)
- DIN 42CrMo4
- JIS SCM440
- BS EN19
Chemical Composition of AISI 4140 Steel Material
| ASTM A29/A29M | C | Si | Mn | P | S | Cr | Mo |
| 4140/G41400 | 0.35～0.40 | 0.20～0.35 | 0.70～0.90 | 0.025 Max | 0.025 Max | 0.80～1.10 | 0.18～0.25 |
| DIN 17220, EN 10083 | C | Si | Mn | P | S | Cr | Mo |
| 1.7225/42CrMo4 | 0.38～0.45 | ≤0.40 | 0.60～0.90 | 0.035 Max | 0.035 Max | 0.90～1.20 | 0.15～0.30 |
| GB/T 1229 | C | Si | Mn | P | S | Cr | Mo |
| 42CrMo | 0.38～0.45 | 0.17～0.37 | 0.50～0.80 | 0.030 Max | 0.030 Max | 0.90～1.20 | 0.15～0.25 |
| JIS G4105 | C | Si | Mn | P | S | Cr | Mo |
| SCM440 | 0.38～0.43 | 0.15～0.35 | 0.60～0.85 | 0.030 Max | 0.030 Max | 0.90～1.20 | 0.15～0.30 |
4. aisi 4140 alloy Steel Equivalent and Related Speciation
| USA | German | Japan | China | ISO |
| ASTM 29/A29M | DIN 17350 | JIS G4404 | GB/T 1229 | ISO 683/18 |
| 4140 | 1.7225/42CrMo4 | SCM440 | 42CrMo | 42CrMo4 |
aisi 4140 Steel Material Mechanical Properties
Mechanical properties of steel 42CrMo4 (1.7225)
| Nominal diameter (mm): | to 16 | 16 – 40 | 40 – 100 | 100 – 160 | 160 – 250 | 250 – 330 | 330 – 660 |
| Rm – Tensile strength (MPa) (+QT) | 1100-1300 | 1000-1200 | 900-1100 | 800-950 | 750-900 | 700 | 600 |
| Nominal thickness (mm): | 0.3 – 3 |
| Rm – Tensile strength (MPa) (+A) | 620 |
| Rm – Tensile strength (MPa) (+AC) | 630 |
| Nominal thickness (mm): | to 8 | 8 – 20 | 20 – 50 | 50 – 80 |
| Rm – Tensile strength (MPa) (+QT) | 1100 | 1000 | 900 | 800 |
| Rm – Tensile strength (MPa) (+C) | 720 |
| Rm – Tensile strength (MPa) (+LC) | 670 |
| Nominal diameter(mm): or for flat products thickness: to 8; 8-20; 20-60; 60-100; 100-160; | to 16 | 16 – 40 | 40 – 100 | 100 – 160 | 160 – 330 | 330 – 660 |
| Re – Upper yield strength or Rp0.2 – 0.2% proof strength (MPa) (+QT) |
900 | 750 | 650 | 500-550 | 460-500 | 390 |
| Nominal thickness(mm): | 0.3 – 3 |
| Rp0.2 0.2% proof strength (MPa) (+A) | 480 |
| KV – Impact energy (J) longitud., (+QT) | +20° 30-35 |
| KV – Impact energy (J) transverse, (+QT) | +20° 22 |
| Nominal thickness (mm): | 0.3 – 3 |
| A – Min. elongation Lo = 80 mm (%) (+A) | 15 |
| A – Min. elongation at fracture (%) transverse, (+QT) | 10-14 |
| A – Min. elongation at fracture (%) (+C) | 4 |
| A – Min. elongation at fracture (%) (+LC) | 6 |
| Nominal thickness (mm): | to 16 | 16 – 40 | 40 – 100 | 100 – 160 | 160 – 250 |
| A – Min. elongation Lo = 5,65 √ So (%) (+QT), round products | 10 | 11 | 12 | 13 | 14 |
| Nominal diameter (mm): or for flat products thickness: to 8; 8-20; 20-60; 60-100; 100-160; | to 16 | 16 – 40 | 40 – 100 | 100 – 160 | 160 – 250 |
| Z – Reduction in cross section on fracture (%) (+QT) | 40 | 45 | 50 | 50 | 55 |
| Z – Reduction in cross section on fracture (%) (+AC) | 57 |
| Brinell hardness (HBW): (+S) | 255 |
| Brinell hardness (HBW): (+A) | 241 |
| Vickers hardness ( HV): (+A) | 195 |
| Vickers hardness ( HV): (+QT) | 340 – 490 |
Forging of ASTM 4140 Oil and Gas industry Steel material metal
Forging of 4140 steel should be carried out between 2200 and 1650 º F (1200 and 900 º C). The lower the finishing temperature from forging, the finer will be the grain size. This alloy steel should ideally not be forged below 1650 º F (900 º C) and should be slow cooled after forging in Oil or water.
Heat Treatment of SAE 4140 Alloy Steel
- ASTM 4140 Steel Annealing
Slowly heat to 800～8500 ºC, keep enough time, ensure heat thoroughly. then cooling in furnace to 480 ºC, then cool in air. After annealing, the hardness 92 HBS Max.
- AISI 4140 Steel Hardening & Quenching
4140 Steel is usually used at 18-22 HRc, If needs, AISI 4140 alloy steel can be hardened or Quenching by cold work. Quenching medium: oil
- Tempering Of ASTM 4140 Alloy Steel
/ ℃ tempering temperature: 205 ~ 649°C.
After tempering hardness HRC: 18-25 HRC.
Conclusion
AISI 4140 alloy steel is a versatile material known for its excellent combination of strength, toughness, and wear resistance. Its balanced chemical composition and mechanical properties make it suitable for a wide range of industrial applications, from automotive to construction. The availability of 4140 in various forms and its international equivalents ensure its adaptability and ease of use in global markets.
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