AISI 4140 Chrome - Moly High Tensile Steel, generally supplied hardened and tempered to Condition “T” in sections up to 100mm, with a tensile strength of 850 – 1000 MPa and aiming for this strength range in larger sections. It offers a very good balance of strength, toughness and wearresistance.
Typical Applications: Axles, conveyor parts, crow bars, gears, logging parts, spindles, shafts, sprockets, studs, pinions, pump shafts, rams, ring gears etc.
Surface Treatment:
Will Nitride with a typical surface hardness up to HRC 60.
Will Flame or Induction harden with a typical surface hardness up to HRC 54.
Chemical Analysis
Carbon 0.40%
Silicon 0.25%
Manganese 0.85%
Chromium 1.00%
Molybdenum 0.25%
Related specifications:
AS 1444-1996 4140
BS 970-3-1991 708M40 or 709M40
BS 970-1955 EN 19A
EN10083-1-1991 1.7225 42CrMo4
JIS G 4105 SCM 440
SAE & UNS 4140 & G41400
| Mechanical Property Requirements in Condition “T”- to AS 1444-1996 |
| Section mm |
0.2% Proof Stress MPa |
Tensile Strength MPa |
Elongation on 5.65√So % |
Impact
Izod Charpy J J |
Hardness HB |
| *up to 63 |
680 min |
850 – 1000 |
9 min |
- - |
248 – 302 |
| up to 100 |
665 min |
850 – 1000 |
13 min |
54 min 50min |
248 – 302 |
| *Applies only to bars bright drawn after hardening and tempering Typical Mechanical Properties – Hardened and tempered in section size listed. |
| Section mm |
Yield Strength MPa |
Tensile Strength MPa |
Elongation % |
Izod J |
Hardness HB |
| 50 |
770 |
930 |
17 |
90 |
275 |
| 100 |
710 |
920 |
15 |
70 |
270 |
| 200 |
570 |
850 |
14 |
60 |
250 |
Typical properties for guidance only
Welding:
Readily welded in the annealed condition but avoid when possible if hardened and tempered due to the effect on the mechanical properties. Welding in the nitrided, flame or induction hardened condition is not recommended.
HEAT TREATMENT
Forging: Heat to 1150°C Hold until uniform Minimum forging temperature 850°C Cool slowly in ashes or sand etc.
Annealing: Heat to 830°C – 850°C
Cool in furnace
Normalising: Heat to 870°C – 900°C
Cool in still air
Stress Relieving:
Annealed: Heat to 600°C – 650°C
Hardened: Heat to 500°C – 550°C
Cool in still air
Hardening:
Heat to 830°C – 880°C
Quench in oil or polymer
Tempering:
Heat to 450°C – 700°C cool in still air
NB. Tempering within the range 200°C
– 420°C will result in temper brittleness and should be avoided
Welding procedure: Low hydrogen electrodes are recommended. Pre-heat at 200°C – 300°C and maintain during welding. Cool slowly in ashes or sand etc and stress relieve if this is possible.
Welding details for guidance only
Flame and Induction Hardening: Heat quickly to the required case depth at 860°C – 890°C and quench immediately in water or oil. Tempering at 150°C – 200°C will reduce stresses in the case with minimal effect on its hardness. All de-carburised surface material must first be removed to ensure best results.
Nitriding:
Heat to 500°C – 530°C and hold for sufficient time to develop the depth of case required Parts should be pre-hardened and tempered as required and also premachined leaving a small grinding allowance only. Heat treatment details for guidance only. |
