Guides/Comparisons
4130 vs 4140 steel
4130-vs-4140-steelAlloy steel AISI 4130 and Alloy steel AISI 4140 at a glance
This page compares Alloy steel AISI 4130 and Alloy steel AISI 4140 using only values that carry a source, a test condition and an evidence level. Ranges run across temper, heat treatment and product form, measured at room temperature where the source says so.
- Composition: Carbon (4130 0.28 to 0.33%; 4140 0.38 to 0.43%), Manganese (4130 0.4 to 0.6%; 4140 0.75 to 1%), Sulfur (4130 up to 0.040%; 4140 up to 0.04%).
- Yield strength: the ranges overlap (4130 435 to 1,330 MPa; 4140 570 to 1,235 MPa).
- Tensile strength: the ranges overlap (4130 655 to 1,600 MPa; 4140 745 to 1,283 MPa).
- Density: the ranges overlap (4130 7.85 g/cm³; 4140 7.85 g/cm³).
- Young's modulus: the ranges overlap (4130 205 GPa; 4140 205 GPa).
- Thermal conductivity: the ranges overlap (4130 30.1 to 42.7 W/(m·K); 4140 42.6 W/(m·K)).
- Thermal expansion: 4140 is higher (4130 3.44 ppm/K; 4140 12.2 to 14.6 ppm/K), about 3.9 times the midpoint of 4130.
- Yield strength for each unit of density (calculated from each grade's midpoint values): Alloy steel AISI 4130 112 MPa per g/cm³; Alloy steel AISI 4140 115 MPa per g/cm³.
"Higher" means the whole range is higher, not just one value. Where a value is a specified minimum, the table says "at least".
Side by side
| Property | Alloy steel AISI 4130 | Alloy steel AISI 4140 |
|---|---|---|
| Yield strength | 435 to 1,330 MPa | 570 to 1,235 MPa |
| Tensile strength | 655 to 1,600 MPa | 745 to 1,283 MPa |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Young's modulus | 205 GPa | 205 GPa |
| Thermal conductivity | 30.1 to 42.7 W/(m·K) | 42.6 W/(m·K) |
| Melting point | 1,432 °C | no data |
| Thermal expansion | 3.44 ppm/K | 12.2 to 14.6 ppm/K |
| Yield strength per densitycalculated | 112 MPa per g/cm³ | 115 MPa per g/cm³ |
Composition
| Element | Alloy steel AISI 4130 | Alloy steel AISI 4140 |
|---|---|---|
| Iron | balance | balance |
| Carbon | 0.28 to 0.33% | 0.38 to 0.43% |
| Manganese | 0.4 to 0.6% | 0.75 to 1% |
| Silicon | 0.15 to 0.35% | 0.15 to 0.35% |
| Chromium | 0.8 to 1.1% | 0.8 to 1.1% |
| Molybdenum | 0.15 to 0.25% | 0.15 to 0.25% |
| Phosphorus | up to 0.035% | up to 0.035% |
| Sulfur | up to 0.040% | up to 0.04% |
Shares are as printed in the sources, by weight.
When to use which
| Material | Best for | Weakest at |
|---|---|---|
| Alloy steel AISI 4130 | Aircraft and motorsport tube, sheet and bar, and oil and gas parts, where weldability and strength after heat treatment both matter | Hydrogen gas and salt solutions: in one laboratory study the threshold stress intensity fell from 88 to 32 MPa√m as hydrogen pressure rose from 21 to 69 MPa, and salt solution cut corrosion-fatigue life |
| Alloy steel AISI 4140 | Machine parts and structures in medium and large sections that need high strength and toughness after quenching and tempering | Hydrogen gas, which cut notched strength by about 60 percent in one room-temperature study, and dilute sulfuric acid, which corroded it at 176.87 mpy |
Where each is used
| Material | Use |
|---|---|
| Alloy steel AISI 4130 | Solid rocket booster case |
| Alloy steel AISI 4130 | Aircraft tube, sheet and bar for military and commercial aircraft |
| Alloy steel AISI 4130 | Oil and gas wellhead and Christmas tree parts |
| Alloy steel AISI 4130 | Machine tool components and forged valve bodies and pumps |
| Alloy steel AISI 4140 | Axles, gears, shafts, spindles, pinions, sprockets and studs |
| Alloy steel AISI 4140 | Rams, crowbars and oil-patch and logging parts |
| Alloy steel AISI 4140 | Aerospace bar to AMS 6349 and AMS 6382 |