ASTM A519 Grade 4145 Alloy Steel Seamless Mechanical Tubing
ASTM A519 Grade 4145 Alloy Steel Seamless Mechanical Tubing
Complete material data for ASTM A519 Grade 4145 chromium-molybdenum alloy steel seamless mechanical tubing used in automotive and structural applications.
Hot finishing, cold finishing, annealing, normalizing, quenching and tempering, stress relieving
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ASTM A519 Grade 4145 Alloy Steel Seamless Mechanical Tubing Introduction
ASTM A519 Grade 4145 is a chromium-molybdenum alloy steel supplied as seamless mechanical tubing. With carbon content between 0.43% and 0.48%, it offers high hardenability, excellent strength, and good toughness after heat treatment. This grade is widely employed for manufacturing highly stressed parts subject to wear and fatigue.
- High tensile and yield strength after quenching and tempering
- Good wear resistance due to Cr-Mo alloying
- Typical applications include drive shafts, axles, and hydraulic cylinder barrels
ASTM A519 Grade 4145 Alloy Steel Seamless Mechanical Tubing Chemical Composition per ASTM A519
The chemical requirements are specified for all heat analysis elements. The steel shall conform to the following limits. No intentional additions of other elements.
| Chemical Element | Standard Value (wt.%) | Remarks |
|---|---|---|
| Carbon (C) | 0.43–0.48 | |
| Manganese (Mn) | 0.75–1.00 | |
| Phosphorus (P) | 0.040 max | |
| Sulfur (S) | 0.040 max | |
| Silicon (Si) | 0.15–0.35 | |
| Chromium (Cr) | 0.80–1.10 | |
| Molybdenum (Mo) | 0.15–0.25 |
ASTM A519 Grade 4145 Alloy Steel Seamless Mechanical Tubing Physical Properties
The physical and thermal properties are representative of low-alloy chromium-molybdenum steels. Values may vary slightly with heat treatment condition and temperature.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20°C |
| Elastic Modulus (E) | 205 | GPa | At 20°C |
| Shear Modulus (G) | 80 | GPa | Calculated |
| Poisson's Ratio (ν) | 0.29 | – | |
| Thermal Expansion Coefficient (α) | 11.5 | ×10⁻⁶/°C | 20–100°C |
| Thermal Conductivity (λ) | 42.6 | W/m·K | At 100°C |
| Specific Heat Capacity | 0.46 | J/g·°C | At 20°C |
| Electrical Resistivity (ρ_e) | 0.22 | Ω·mm²/m | At 20°C |
ASTM A519 Grade 4145 Alloy Steel Seamless Mechanical Tubing Typical Mechanical Properties
Mechanical properties in ASTM A519 are not fixed; they must be agreed between purchaser and manufacturer. The following are typical values for 4145 alloy steel oil-quenched from 845°C and tempered at 540°C. Note: Properties strongly depend on tempering temperature; lower tempering increases strength but reduces toughness.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Tensile Strength (Rm) | 965 | MPa | Oil quenched, tempered at 540°C |
| Yield Strength (ReH 0.2%) | 760 | MPa | Oil quenched, tempered at 540°C |
| Elongation (A5) | 15 | % | Gauge length 50 mm |
| Reduction of Area (Z) | 45 | % | |
| Hardness (HBW) | 302 | HB | Quenched and tempered |
| Charpy Impact (KV) | 45 | J | Room temp., tempered at 205°C |
ASTM A519 Grade 4145 Alloy Steel Seamless Mechanical Tubing Fully Equivalent Material Standards and Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3441 | SCM445 | Comparable Cr-Mo steel, carbon 0.43–0.48% |
| Europe | EN 10297-1 | 42CrMo4+HH | Modified high-carbon variant to match 4145 carbon range |
ASTM A519 Grade 4145 Alloy Steel Seamless Mechanical Tubing Application Introduction
ASTM A519 4145 seamless tubing is selected for applications demanding high strength, fatigue resistance, and toughness. It is typically heat treated to achieve the required mechanical properties. Common usage includes:
Product Applications: Drive shafts, Axle tubes, Hydraulic cylinder barrels, Bearing rings and bushings
Processed into products: Seamless tubular power transmission shafts, Steering shaft tubes, Heavy equipment pivot pins, Cylinder liners and sleeves
Application industries: Automotive, Construction & heavy machinery, Oil and gas equipment, Railway components
ASTM A519 Grade 4145 Alloy Steel Seamless Mechanical Tubing Similar / Neighbouring Substitution Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A519 | 4140 | Lower carbon (0.38–0.43%), somewhat lower strength |
| USA | ASTM A519 | 4142 | Carbon 0.40–0.45%, intermediate properties |
| Europe | EN 10083-3 | 42CrMo4 (1.7225) | Widely used, carbon 0.38–0.45% |
| China | GB/T 3077 | 42CrMoA | Carbon 0.38–0.45%, similar hardenability |
Notes:
Supplementary requirements: Tensile tests, hardness limits, or non-destructive examination must be specified at the time of order. This grade is not intended for pressure vessel service (see ASTM A106, A179 for such applications). For improved weldability, lower carbon grades like 4140 may be preferred.
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