ASTM A519 4140 (UNS G41400) Seamless Alloy Steel Mechanical Tubing
ASTM A519 Grade 4140 (UNS G41400) seamless mechanical tubing is a high-strength chromium-molybdenum alloy steel known for its outstanding hardenability, toughness, fatigue resistance, and wear properties. This grade is widely used in high-stress, high-load applications across oil & gas, automotive, aerospace, mechanical engineering, and heavy machinery manufacturing. Produced through hot-finished or cold-drawn processes, A519 4140 offers precise dimensional accuracy, uniform mechanical performance, and excellent response to quenching and tempering. Its superior strength-to-weight ratio makes it a preferred choice for demanding engineering components requiring high reliability and durability.
Key Features
- High strength and excellent fatigue resistance
- Superior hardenability and wear resistance
- Outstanding performance after heat treatment (Q&T, normalized, annealed)
- Great toughness and impact resistance
- Smooth surface finish with precise dimensional control
- Excellent machinability in heat-treated condition
- Preferred for heavy-duty and high-stress engineering parts
Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| AISI / SAE | 4140 |
| UNS | G41400 |
| DIN | 1.7225 |
| EN | 42CrMo4 |
| JIS | SCM440 |
ASTM A519 4140 Chemical Composition
| Element | Percentage (%) |
|---|---|
| Carbon (C) | 0.38 – 0.43 |
| Manganese (Mn) | 0.75 – 1.00 |
| Chromium (Cr) | 0.80 – 1.10 |
| Molybdenum (Mo) | 0.15 – 0.25 |
| Silicon (Si) | 0.15 – 0.30 |
| Sulfur (S) | ≤ 0.040 |
| Phosphorus (P) | ≤ 0.035 |
| Iron (Fe) | Balance |
ASTM A519 4140 Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | 655 – 850 MPa |
| Yield Strength | 415 – 540 MPa |
| Elongation | 15 – 20% |
| Hardness | 197 – 235 HB (Annealed) |
Physical Properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Modulus of Elasticity | 205 GPa |
| Thermal Conductivity | 42 W/m-K |
| Melting Point | ~1430°C |
Type of Grade 4140 Tubes
- Seamless Mechanical Tubing
- Cold Drawn Seamless Tubing
- Hot Finished Seamless Tubing
- Annealed Tubing
- Normalized Tubing
- Quenched & Tempered Tubing
- Precision Cut-to-Length Tubes
Applications
- Oil & gas drilling tools and equipment
- Automotive axle shafts, gears, crankshafts
- Heavy machinery components
- Aerospace structural elements
- Hydraulic cylinders and high-pressure equipment
- Power transmission parts
- Industrial mechanical shafts and forged components
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