Designation
DIN: | 42 CrMo 4
|
AFNOR: | 42 CD 4 |
UNI: | 42 CrMo 4 |
AISI: | 4140 |
Chemical composition:
C | 0.42 |
Si | 0.25 |
Mn | 0.75 |
S | <0.035 |
Cr
| 1.10
|
Mo
| 0.22 |
Strength:
max. 217 HB
(≈ max. 740 N/mm²)
Tensile strength:
heat treated max. 720 N/mm²
Thermal conductivity at 20 °C:
42.6 W/m K
Character:
alloyedsteel, suitable for quenching and tempering, steel with high resistance and high toughness;
universally usable in engineering
Application:
machine construction, base plates, axes, gear shafts, gear wheels
Treatment by
is possible:
Nitriding, EDM, coating
unusual:
Welding
Heat treatment:
Normalising:
840 to 880 °C afterwards cooling in air; some components need tempering afterwards
Soft annealing:
680 to 720 °C for about 2 to 5 hours; slow controlled cooling of 10 to 20 °C per hour to about 600 °C; further cooling in air. Maximum 217 HB
Quenching:
max. 1.600 N/mm²
Hardening:
820 - 880 °C
quenching in oil or water
oil hardening for thin and complex,
water hardening for large and simple components
obtainable hardness: 53-61 HRC
Tempering:
slow heating to tempering temperature (to avoid forming of cracks) immediately after hardening; at least 60 minutes cooling in air
Annealing graph:
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