Carbon & alloy steel · EN 10083-3
42CrMo4 (4140) Q&T
Also known as: 1.7225, 4140, 42CrMo4
Overview
Chromium-molybdenum alloy steel (42CrMo4 / AISI 4140) Q&T — default high-strength shaft and machine-steel grade in PhyCalcPro.
Typical supply: Bars, forgings, tubes
Mechanical Properties
Young's modulus E210 GPa
Shear modulus G80.8 GPa
Yield / proof Re750 MPa
Ultimate Rm1e+3 MPa
Poisson's ratio ν0.3
Endurance limit Se480 MPa
Hardness300 HB
Shear strength600 MPa
Bearing strength2e+3 MPa
Thermal Properties
Thermal expansion α12 µm/(m·K)
For temperature derating, open Temperature Properties.
Physical Properties
Density ρ8e+3 kg/m³
Specific strength Sy/ρ9.55e+4 Pa·m³/kg
Specific stiffness E/ρ2.68e+7 Pa·m³/kg
Typical supply: Bars, forgings, tubes
Density ~7850 kg/m³. Bars, forgings, tubes.
Applications
- Power-transmission shafts
- Crankshafts and connecting rods
- High-strength fasteners (selected)
- Gears and spindles
Advantages
- Default high-strength shaft steel with excellent hardenability
- Strong fatigue performance when QT correctly
- Widely available globally as bar and forging stock
Limitations
- Not stainless — needs corrosion protection
- Weldability requires preheat / PWHT practices
- QT condition reduces machinability vs annealed
Standards
- EN 10083-3 — Quenched and tempered steels — alloy
- ASTM A29 — 4140 / 4142 bar
Equivalent Materials
Electrical Properties
Resistivity2.200e-7 Ω·m
Chemical Composition
| Element | Min wt% | Max wt% | Typical wt% |
|---|---|---|---|
| C | 0.38 | 0.45 | 0.41 |
| Si | — | 0.4 | — |
| Mn | 0.6 | 0.9 | 0.75 |
| P | — | 0.025 | — |
| S | — | 0.035 | — |
| Cr | 0.9 | 1.2 | 1 |
| Mo | 0.15 | 0.3 | 0.22 |
Typical / limit values for reference selection only — verify against mill certs for certified work.
Machinability
Machinability ~55% of free-cutting steel in annealed state; QT reduces tool life.
Cost
Moderate alloy premium; widely available globally.
Corrosion
Not stainless — protect with oil, plating, or paint.
- Oil-lubricated machineryfair
- Outdoor uncoatedpoor
For allowance / life screening, open Corrosion Allowance.