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Technical Specifications
Product Overview
AISI 4140 Annealed Cold Rolled Round Bar is a versatile chromium-molybdenum alloy steel known for its excellent combination of strength, toughness, and wear resistance. This low-alloy steel is supplied in the annealed condition for optimal machinability and formability.
Key Features:
- Excellent hardenability and through-hardening capability
- Good fatigue resistance and impact strength
- Superior machinability in annealed condition
- Excellent response to heat treatment
- Good weldability with proper preheating
Manufacturing Process: Cold rolled from hot rolled bar stock, then annealed to achieve optimal microstructure for machining. Precision cold drawing ensures excellent dimensional accuracy and surface finish.
Applications: Automotive components (axles, crankshafts, gears), machine tool components, hydraulic shafts, pump shafts, bolts and studs, pressure vessel components, and general machinery parts requiring high strength and toughness.
🧪 Chemical Composition
| Element | Min % | Max % | Typical % | AISI 4140 Requirement |
|---|---|---|---|---|
| Carbon (C) | 0.38 | 0.43 | 0.40 | 0.38-0.43 |
| Chromium (Cr) | 0.80 | 1.10 | 0.95 | 0.80-1.10 |
| Molybdenum (Mo) | 0.15 | 0.25 | 0.20 | 0.15-0.25 |
| Manganese (Mn) | 0.75 | 1.00 | 0.85 | 0.75-1.00 |
| Silicon (Si) | 0.15 | 0.35 | 0.25 | 0.15-0.35 |
| Phosphorus (P) | - | 0.035 | 0.020 | ≤ 0.035 |
| Sulfur (S) | - | 0.040 | 0.025 | ≤ 0.040 |
| Nickel (Ni) | - | 0.30 | 0.15 | ≤ 0.30 |
| Iron (Fe) | Balance | Balance | 97.4 | Balance |
⚙️ Mechanical Properties
| Property | ASTM Requirement | Typical Value | Test Method | Temperature |
|---|---|---|---|---|
| Tensile Strength | 655 MPa min | 720 MPa | ASTM A370 | Room Temp |
| Yield Strength (0.2%) | 415 MPa min | 460 MPa | ASTM A370 | Room Temp |
| Elongation | 25% min | 28% | ASTM A370 | Room Temp |
| Reduction of Area | 50% min | 55% | ASTM A370 | Room Temp |
| Hardness (Brinell) | 197 HB max | 190 HB | ASTM E10 | Room Temp |
| Hardness (Rockwell B) | 92 HRB max | 88 HRB | ASTM E18 | Room Temp |
| Modulus of Elasticity | - | 205 GPa | ASTM E111 | Room Temp |
| Impact Energy (Charpy V) | - | 54 J | ASTM E23 | Room Temp |
🔬 Physical Properties
| Property | Value | Unit | Temperature | Test Standard |
|---|---|---|---|---|
| Density | 7.85 | g/cm3 | 20¡ãC | ASTM B311 |
| Melting Point | 1416-1460 | ¡ãC | - | DSC Analysis |
| Thermal Conductivity | 42.6 | W/m·K | 100¡ãC | ASTM E1461 |
| Specific Heat | 475 | J/kg·K | 0-100¡ãC | ASTM C351 |
| Linear Expansion | 12.2 | μm/m·K | 0-100¡ãC | ASTM E228 |
| Electrical Resistivity | 240 | nΩ·m | 20¡ãC | ASTM B193 |
| Magnetic Permeability | Ferromagnetic | - | Room Temp | ASTM A342 |
| Curie Temperature | 770 | ¡ãC | - | Magnetic analysis |
📏 Product Specifications
| Specification | Available Range | Standard Size | Custom Available | Tolerance |
|---|---|---|---|---|
| Diameter | 3mm - 300mm | Various | Yes | h9 (±0.025mm) |
| Length | 1m - 12m | 6m | Yes | +25mm/-0mm |
| Surface Finish | Cold Drawn, Polished | Cold Drawn | Yes | Ra ≤ 1.6μm |
| Straightness | 0.5mm/m max | Standard | Precision | ±0.5mm/m |
| Heat Treatment | Annealed | Annealed | Custom HT | Per ASTM A29 |
| End Condition | Sawed, Machined | Sawed | Yes | Square ±1¡ã |
| Standards Compliance | ASTM A29, A108, A311 | A108 | Multiple | Full compliance |
| Condition | Annealed, Normalized | Annealed | Yes | 197 HB max |
| Test Certificate | Mill TC, EN 10204 3.1 | Mill TC | Yes | Standard |
| Packaging | Bundles, Crates | Bundles | Custom | Export standard |
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Our Advantages in Processing Barra redonda laminada a frio recozida 4140
Enhanced Dimensional Accuracy
The cold rolling process ensures superior dimensional precision and consistency throughout the bar length, resulting in tighter tolerances and reduced machining allowances. This precision manufacturing enables better fit and compatibility in final applications.
Improved Surface Finish
Cold rolling produces an exceptionally smooth surface finish with consistent texture and minimal surface defects. This superior finish reduces the need for additional surface treatment and enhances the material's resistance to wear and corrosion.
Optimized Annealing Process
The carefully controlled annealing treatment softens the material structure, improving machinability while maintaining optimal mechanical properties. This process reduces tool wear during subsequent machining operations and ensures consistent material properties.
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