42CrMo4 (4140) Engineering Steel
1.7225
- EN1.7225
- EN42CrMo4
- AISI4140
- UNSG41400
The most widely used chromium-molybdenum quenched and tempered steel. In the QT condition it offers high strength, good toughness and fatigue strength with uniform hardening in medium sections. The standard shaft and gear steel of machine building.
01Material Properties
- Rm 900–1100 MPa (+QT, ≤ 100 mm)
- Good toughness and fatigue strength
- Medium to good hardenability
- Induction / flame surface hardening
- Suitable for nitriding
- Good machinability in QT condition
02Applications
- Shafts, axles, crankshafts
- Gears and pinions
- High-strength bolts (10.9 / 12.9)
- Hydraulic and pneumatic cylinder parts
- Die holders and machine bodies
03Delivery Condition
- Quenched and tempered (+QT) or soft annealed (+A, max. 241 HB); peeled / ground bar.
04Heat Treatment
Typical values
- Soft annealing
- 680–720 °C; max. 241 HB
- Normalising
- 825–865 °C, air
- Hardening
- 830–860 °C; oil or polymer
- Tempering (QT)
- 540–660 °C, 1–2 h
- After QT (+QT)
- Rm 900–1100 MPa, Rp0.2 ≥ 650 MPa (≤ 100 mm)
- Surface hardening
- Induction / flame; nitriding possible
Heat treatment cycle (schematic)
Tempering diagram (approximate)
Values are approximate and for information only; they vary with section size, heat and furnace conditions. Binding values are determined from the manufacturer’s data under laboratory conditions.
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