4140 Hard Chrome Plated Bar

4140 is a 1% Chromium - Molybdenum high tensile steel supplied in the hardened and tempered, cold drawn or turned, precision ground, polished, chrome plated and final polished condition, with a typical base metal tensile strength of 850 - 1000 Mpa, plus a typical hard chrome plated surface hardness of HV 1000 - 1150.

Characterised by an extremely smooth surface finish with excellent wear and corrosion resistance, coupled with a base material giving high strength and good impact properties, plus good machinability.
4140 hard chrome plated bar is used extensively by the hydraulic and pneumatic industries, and is employed by other industry sectors for a wide range of applications requiring higher strength.
Typical applications are: Agricultural Equipment, Hydraulic Cylinders, Hoists, Jacks and other Lifting equipment, Machine Tools, Mining and Earth Moving Equipment, Pumps, Valves, Waste Disposal Transport and Equipment etc.
Colour Code Stocked Sizes
Dark Green (End Caps)

Metric 20 mm - 140 mm Dia
Imperial 7/8" - 5" Dia
Related Specifications
Australia AS 1444 - 1996 4140
Germany W.Nr 1.7223 41CrMo4
W.Nr 1.7225 42CrMo4
Great Britain BS970 - Part 3 - 1991 709M40
BS970 - 1955 EN19A
Japan JIS G 4105 SCM 440
USA ASTM A29/A29M - 91 4140
UNS G41400
Chemical Composition (Base Material)
Min. % Max %
Carbon 0.36 0.44
Silicon 0.10 0.40
Manganese 0.65 1.10
Chromium 0.75 1.20
Molybdenum 0.15 0.35
Phosphorous 0 0.04
Sulphur 0 0.04
Typical (Base Metal) Mechanical Properties - As Supplied Condition
Manufacturing Process Turned
Tensile Strength Mpa 900
Yield Strength Mpa 800
Elongation In 50mm % 20
Hardness Brinell HB 270
Typical Properties Induction Hardened Case
Thickness 3.2mm
Hardness Rc 55-65
Hard Chrome Plating
Typical Surface Hardness HV 1000 - 1150
Typical Surface Smoothness 0.10 - 0.30 umRa (Microns)
Typical Surface Deposit* 0.025 - 0.050mm
(0.001") - (0.002")
*Note: Can be supplied up to 0.125 mm against order, subject to minimum quantity requirements.
Diameter and Straightness Tolerance
Diameter mm Up to 51mm Dia Over 51 - 102mm Dia Over 102mm Dia Straightness
Inches Up to 2.0 Over 2.0 - 4.0 Over 4.0 Below 50mm 0.25mm/1000mm
Over 50mm 0.30mm/1000mm
Tolerance mm +0.00 -0.025 +0.00 -0.050 +0.00 -0.075
Inches +0.00 -0.001 +0.00 -0.002 +0.00 -0.003
Typical Bar Lengths
Up to 18mm Dia 2000mm - 3600mm
19.05mm to 25mm Dia 4000mm
Over 25mm Dia 6000mm
Bar lengths are approximates only.
NB. Bars have 100mm approx. unchromed surface at each end.
Supplied in cardboard tubes for protection.
4140 hard chrome plated bar has very good machinability, similar to 4140 uncoated bar. Machining however should commence beneath the chrome plating, or at the unchromed surface at the end of the bar. To protect the polished chrome surface, soft materials such as copper, aluminium or mild steel should be used as clamping materials and any particles of hard chrome should be removed immediately to avoid scratching. Otherwise all machining operations may be carried out satisfactorily.
Welding 4140 hard chrome bar in the hardened and tempered as supplied condition is not recommended and should be avoided if at all possible, as the mechanical properties will be altered within the weld heat affected zone. If however welding is really necessary the following procedure may be taken as a guide only..
Welding Procedure
The cardboard tube protecting the chrome plating should first be removed from the heat affected area otherwise it can cause some corrosion of the plating due to fumes emitted.Welding should always be carried out using low hydrogen electrodes.

Please consult your welding consumables supplier.
Suggested pre-heat temperature
Section 25mm 50mm 75mm 150mm +
oC 370 425 460 510
Post Welding
Maximum cooling rate 95 oC per hour down to 95 oC, followed by cooling in still air. NB. No draught. It is recommended that the weld area if possible is wrapped in a heat resistant blanket or buried in sand, dry lime etc.
Interlloy believes the information provided is accurate and reliable. However no warranty of accuracy, completeness or reliability is given, nor will any responsibility be taken for errors or omissions.