4140 Cold Rolled Alloy Steel Bar

4140 Cold Rolled Alloy Bar

4140 Cold Rolled Round Bar is ideal for most machining processes. 4140 Annealed Cold Rolled Bar is a high strength, wear resistant alloy. Its extremely high dimensional accuracy, straightness and concentricity combine to minimize wear in high speed applications. Commonly used in the manufacture of gears, shafts, axles, bolts, studs and machine parts. Widely used in the automotive, defense, agriculture, aerospace and oil and gas industries.

AISI 4140 Cold-Rolled Bar: Comprehensive Properties

(Conforms to ASTM A829, ISO 683-18, GB/T 3077 Standards)

Property	Specification	Technical Details
Dimensions	Size Range	Thickness: 5 - 50 mm<br>Width: 20 - 200 mm<br>Length: 3 - 12 m
Tolerances	Thickness/Width Precision	±0.05 mm (T ≤ 30 mm)<br>±0.1 mm (T > 30 mm)<br>±0.1% Width (CR precision)
Surface Treatment	Options	Ground (Ra ≤ 0.8 μm)<br>Phosphated (+ Oil Seal)<br>Nickel Plated (10-30 μm)
Hardness	As-Rolled State	280 - 320 HB<br>30 - 35 HRC
Density	Physical Property	7.85 g/cm³
Material Grade	International Standards	AISI 4140 / DIN 1.7225 / JIS SCM440 / GB 42CrMo
Key Applications	Industrial Sectors	Precision Shafts<br>Hydraulic Pistons<br>Mold Inserts<br>Gear Blanks

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Mechanical Properties & Processing Data

Mechanical Property	Cold-Rolled State	After Heat Treatment
Tensile Strength	850 - 1000 MPa	1150 - 1400 MPa (QT)
Yield Strength	≥ 700 MPa	≥ 950 MPa (QT)
Elongation	8 - 12%	10 - 15% (QT)
Impact Toughness	25 - 35 J	20 - 30 J (QT)
Straightness Tolerance	≤ 0.3 mm/m	≤ 0.1 mm/m (Precision Ground)

CHEMICAL COMPOSITION
Element	Percentage
C	0.38 - 0.43
Cr	0.8 - 1.1
Fe	96.785 - 97.84
Mo	0.15 - 0.25
Mn	0.7 - 1
P	0.035 max
Si	0.15 - 0.3
S	0.04 max

AISI 4140 Cold-Rolled Bar: Market Standard Sizes

(Compliant with ASTM A829 / GB/T 702-2017 Standards)

Thickness (mm)	Width (mm)	Length (m)	Tolerance Class	Theoretical Weight (kg/m)	Unit Price Reference (USD/kg)
5.0 - 10.0	20 - 100	3.0 - 4.5	h9 (±0.025mm)	[Thickness×Width×0.00785]	2.8 - 3.2
10.1 - 20.0	50 - 150	4.0 - 6.0	h10 (±0.04mm)	[Thickness×Width×0.00785]	2.6 - 3.0
20.1 - 30.0	100 - 200	4.5 - 8.0	h11 (±0.05mm)	[Thickness×Width×0.00785]	2.4 - 2.8
30.1 - 50.0	150 - 300	6.0 - 12.0	h12 (±0.1mm)	[Thickness×Width×0.00785]	2.2 - 2.6

GNEE Group 4140 Steel Bar Factory Environment

GNEE Group 4140 metal Steel Bar Packaging

GNEE Group 4140 Bar Testing

Is 4140 alloy steel corrosion resistant?
Although 4140 steel contains chromium to improve corrosion resistance, it is not highly resistant to corrosion. Appropriate coatings or protective measures are recommended for use in corrosive environments.
What is the difference between 4140 and 4340 alloy steels?
4140 steel has a lower carbon content than 4340 steel, making it easier to machine. However, 4340 steel has higher strength and toughness, especially in larger sections, and is often used in heavy-duty applications.
Can 4140 alloy steel be welded?
Yes, 4140 steel can be welded using the proper welding techniques and precautions. However, post-weld heat treatment may be required to restore its properties, especially in the heat-affected zone.
What is the maximum hardness that 4140 steel can achieve through heat treatment?
Depending on the specific heat treatment process, 4140 steel can reach a hardness of up to approximately 58-60 HRC.
Is 4140 alloy steel round bar available in a variety of sizes and shapes?
Yes, 4140 Alloy Steel Round Bar is available in a variety of sizes and can also be made into a variety of shapes including square bars and flat bars to suit a variety of applications.

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