4140

Description:4140 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.

APPLICATIONS:

It is the most commonly used of the high tensile steels with a wide range of applications in automotive, Gear and Engine construction, Crankshafts, Steering knuckles, Connecting rods, Spindles, Intermediate gears, Pump and Gear shafts, Axles, Nuts and Bolts, bearing, gear, transmission gear, supercharger gear, engine cylinder, spring, 1200mm-2000mm rotary shouldered connections for petroleum industry, jar knocker.

RELATED SPECIFICATIONS:

Australia AS 1444-2007 4140

AMS 6378, AMS 6379 , AMS 6381B , AMS 6382 , AMS 6382G , AMS 6390 , AMS 6390A , AMS 6395

Germany DIN 17212 W.Nr. 1.7223 Type 41CrMo4

DIN 17200 1654 W.Nr 1.7225 Type 42CrMo4

DIN 17200 W.Nr 1.7227 Type CrMoS4

EN10083 11991 1.7225 42CrMo4

Great Britain BS970 1955 EN19A

BS970 Part 3:1991708M40 or 709M40 or 708 A 42

Sweden: SS 2244

France AFNOR 40 CD 4 , AFNOR 42 CD 4

Italy: UNI 38 CrMo 4 KB , UNI 40 CrMo 4 , UNI G 40 CrMo 4

USA ASTM A29A29M91 4140

ASTM A322 4140

ASTM A331 4140 cold finish

SAE 4140, SAE J404 , SAE J412 , SAE J770 , UNS G41400

ASTM A331 , ASTM A505 , ASTM A519 , ASTM A547 , ASTM A646 ,

MIL SPEC MILS1 6974 ,

Japan JIS G 4103 SNCM4

JIS G 4105 SCM4

JIS G 4105 SCM440

Chemical Composition (%):

Carbon 0.38-0.45

Silicon 0.17-0.37

Manganese 0.50-0.80

Phosphorus 0.04 max

Sulphur 0.04 max

Chromium 0.90-1.20

Molybdenum 0.15-0.25

Process: EAF+LF+VOD+Forged or Rolled+Heat Treatment(optional)

SIZE RANGE:

Round:

Hot Rolled: 8mm-500mm

Hot Forged: 80mm-1200mm

Flat:

Hot rolled: Thickness: 20-130mm Width: less than 610mm

Hot forged: Thickness:150-600mm Width: up to 1600mm

SURFACE FINISHES:

Black, Peeled(K12), Cold Drawn, Turned & Polished(H10, H11), Precision Ground(H9, H8)

COLOUR CODE: WHITE END

Test: Ultrasonic test according to SEP 1921-84 3Cc

Forging:
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.
Heat Treatment
Annealing
Heat to 800 oC - 850 oC, hold until temperature is uniform throughout the section and cool in furnace.
Flame or Induction Hardening
4140 hardened and tempered bar can be further surface hardened by either the flame or induction hardening methods resulting in a case hardness in excess of Rc 50.
Parts should be heated as quickly as possible to the austenitic temperature range (840 C - 870 C) and "required case depth followed by an immediate oil or water quench, depending upon hardness required, workpiece" size/shape and quenching arrangements.
"Following quenching to hand warm, most components should be tempered between 150 C - 200 C to remove" quenching stresses in the case. This will have little effect on case hardness and will reduce the risk of grinding cracks.
Hardening
Heat to 840 oC - 875 oC, hold until temperature is uniform throughout the section, soak for 10 - 15 minutes per 25 mm section, and quench in oil, water, or polymer as required.
*Temper immediately while still hand warm.
Nitriding
4140 hardened and tempered bar can also be successfully nitrided, giving a surface hardness of up to Rc 60. Nitriding is carried out at 490 oC - 530 oC, followed by slow cooling (no quench) reducing the problem of distortion. Parts can therefore be machined to near final size, leaving a grinding allowance only. The tensile strength of the core is usually not affected since the nitriding temperature range is generally below the original tempering temperature employed.
Normalizing
Heat to 870 oC - 900 oC, hold until temperature is uniform throughout the section, soak for 10 - 15 minutes and cool in still air.
Stress Relieving
Heat to 680 oC - 700 oC, hold until temperature is uniform throughout the section, soak for 1 hour per 25 mm section, and cool in still air.
Tempering
Re-heat to 550 oC - 700 oC as required, hold until temperature is uniform throughout the section, soak for 1 hour per 25 mm of section, and cool in still air.
Notes on Heat Treatment
Heating temperatures, rate of heating and soaking times will vary due to factors such as work piece size/shape also furnace type employed, quenching medium and work piece transfer facilities etc..

Machining
4140 in the hardened and tempered as supplied condition has good to very good machinability and operations such as sawing, turning, drilling, broaching, hobbing, milling and tapping can be carried out satisfactoraly using machine manufacturers recommendations for suitable tool type - feeds and speeds.

Certificate of Quality: issued in English, in addition the normal terms, production process, the mechanical property yield strength, tensile strength, elongation and hardness, forged ratio, UT test result, Grain size, heat treatment methods and the sample of is shown on the Certificate of Quality.

Marking: Heat No. will be cold stamped and Steel grade, diameter mm, length mm, and the manufacturer LOGO and weight kg is painted