Introduction
Alloy steels contain elements such as chromium, cobalt, nickel etc. In comparison with carbon steels, alloy steels are a lot more responsive to mechanical and heat treatments.
Alloy steels comprise a wide range of steels whose compositions exceed the limitations of Si, Va, Cr, Ni, Mo, Mn, B and C allocated for carbon steels. These steels can be subjected to unique melting and deoxidization processes for specific kind of applications.
The following datasheet provides an overview of AISI E4340 alloy steel.
Chemical Composition
The chemical composition of AISI E4340 alloy steel is outlined in the following table.
| Element | Content (%) |
| Iron, Fe | 95.175-96.27 |
| Nickel, Ni | 1.65-2.00 |
| Chromium, Cr | 0.700-0.900 |
| Manganese, Mn | 0.650-0.850 |
| Carbon, C | 0.380-0.430 |
| Molybdenum, Mo | 0.200-0.300 |
| Silicon, Si | 0.150-0.300 |
| Phosphorous, P | GBP 0.0250 |
| Sulfur, S | GBP 0.0200 |
Physical Properties
The following table shows the physical properties of AISI E4340 alloy steel.
| Properties | Metric | Imperial |
| Density | 7.85 g/cm3 | 0.284 lb/in3 |
Mechanical Properties
The mechanical properties of annealed AISI E4340 alloy steel are displayed in the following table.
| Properties | Metric | Imperial |
| Tensile strength | 745 MPa | 108000 psi |
| Yield strength | 470 MPa | 68200 psi |
| Bulk modulus (typical for steel) | 140 GPa | 20300 ksi |
| Shear modulus (typical for steel) | 80.0 GPa | 11600 ksi |
| Elastic modulus | 190-210 GPa | 27557-30458 ksi |
| Poisson's ratio | 0.27-0.30 | 0.27-0.30 |
| Elongation at break (in 50 mm) | 22.00% | 22.00% |
| Reduction of area | 50.00% | 50.00% |
| Hardness, Brinell | 217 | 217 |
| Hardness, Knoop (converted from Brinell hardness) | 240 | 240 |
| Hardness, Rockwell B (converted from Brinell hardness) | 95 | 95 |
| Hardness, Rockwell C | 17 | 17 |
| Hardness, Vickers (converted from Brinell hardness) | 228 | 228 |
| Machinability | 50 | 50 |
Thermal Properties
The thermal properties of AISI E4340 alloy steel are given in the following table.
| Properties | Metric | Imperial |
| Thermal expansion co efficient 545 C temper for 2 hrs | 11.3 m/m C | 6.28 in/in F |
| Thermal conductivity (typical steel) | 44.5 W/mK | 309 BTU in/hr.ft2.F |
Other Designations
Equivalent materials to AISI E4340 alloy steel are given in the following table.
| AMS 6415 | ASTM A331 | ASTM A519 | ASTM A752 | ASTM A829 |
| MIL S-5000 | MIL S-83135 | SAE J1397 | SAE J404 | ASTM A304 |
| ASTM A505 | SAE J770 | MIL SPEC MIL-S-5000 |
Applications
AISI E4340 alloy steel is used in pressure vessels, piston pins, dies, bearings, gears and ordnance.
Source - www.azom.com
(www.steelguru.com)
