Hot Rolled 42crmo Alloy Steel Round Bar For Bolts Making With
Turned Surface
1. 4140 alloy steel is a 1% chromium - molybdenum medium
hardenability general purpose high tensile steel - generally
supplied hardened and tempered in the tensile range of 850 - 1000
Mpa (condition T).4140 is now available with improved
machinability, which greatly increases feeds and/or speeds, while
also extending tool life without adversley affecting mechanical
properties.
Pre hardened and tempered 4140 can be further surface hardened by
flame or induction hardening and by nitriding.
4140 is used extensively in most industry sectors for a wide range
of applications such as:
Adapters, Arbors, Axle Shafts, Bolts, Crankshafts, Connection Rods,
Chuck Bodies, Collets, Conveyor Pins & Rolls, Ejector Pins, Forks,
Gears, Guide Rods, Hydraulic Shafts & Parts,Lathe Spindles, Logging
Parts, Milling Spindles, Motor Shafts, Nuts, Pinch Bars, Pins
Various, Pinions, Pump Shafts, Rams, Sockets, Spindles, Sprockets,
Studs, Tool Holders, Torsion Bars, Worms etc..
2. Common 4140 Steel Specifications
3. 4140 Steel Bar Chemical Composition
| Standard | Grade | C | Mn | P | S | Si | Ni | Cr | Mo |
| ASTM A29 | 4140 | 0.38-0.43 | 0.75-1.00 | 0.035 | 0.040 | 0.15-0.35 | – | 0.8-1.10 | 0.15-0.25 |
| EN 10250 | 42CrMo4/
1.7225 | 0.38-0.45 | 0.6-0.9 | 0.035 | 0.035 | 0.4 | – | 0.9-1.2 | 0.15-0.30 |
| JIS G4105 | SCM440 | 0.38-0.43 | 0.60-0.85 | 0.03 | 0.03 | 0.15-0.35 | – | 0.9-1.2 | 0.15-0.30 |
4. Mechanical Properties of AISI Alloy 4140 Steel Bar, Plates, Square
| Properties | Metric | Imperial |
| Tensile strength | 655 MPa | 95000 psi |
| Yield strength | 415 MPa | 60200 psi |
| Bulk modulus (typical for steel) | 140 GPa | 20300 ksi |
| Shear modulus (typical for steel) | 80 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) | 25.70% | 25.70% |
| Hardness, Brinell | 197 | 197 |
| Hardness, Knoop (converted from Brinell hardness) | 219 | 219 |
| Hardness, Rockwell B (converted from Brinell hardness) | 92 | 92 |
| Hardness, Rockwell C (converted from Brinell hardness. Value below
normal HRC range, for comparison purposes only) | 13 | 13 |
| Hardness, Vickers (converted from Brinell hardness) | 207 | 207 |
| Machinability (based on AISI 1212 as 100 machinability) | 65 | 65 |
5. Forging
Preheat the steel carefully, heat to 1150 oC – 1200 oC maximum,
hold until temperature is uniform throughout the section.
Do not forge below 850 oC.Following forging operation the work
piece should be cooled as slowly as possible.
