SAE 4140 Alloy Steel bar|AISI 4140-ASTM A29

SAE 4140 Alloy Steel bar | AISI 4140-ASTM A29

In the ASTM A29 standard, SAE 4140 belongs to chromium-molybdenum low alloy structural steel.

After quenching and tempering, the comprehensive performance of SAE 4140 steel is further improved. With its excellent strength, toughness, wear resistance and impact resistance, SAE 4140 steel is widely used in the industrial field.

In the annealed condition, SAE 4140 steel is easily machinable.SAE 4140 steel is usually used in the quenched and tempered condition with pre-hardening hardness 28-34HRC.

SAE 4140 Steel Application

Automotive industry: Critical parts such as crankshafts, gears and axles
Oil and gas industry: Drill collars and drill pipe joints
Construction industry: Structural parts
Machinery manufacturing: shafts, spindles, steering wheels, bolts, studs, gears

SAE 4140 Steel Chemical Composition

Grade	C	Si	Mn	P	S	Cr	Mo
4140	0.38-0.43	0.15-0.35	0.75-1.00	≤0.035	≤0.04	0.8-1.1	0.15-0.25

QUICK FAQS FOR SAE 4140 STEEL

What is the difference between SAE 4140 and AISI 4140?

In fact, there is no fundamental difference between SAE 4140 and AISI 4140.In practical applications, engineers do not treat them differently.

4140 Steel VS 42CrMoA

42CrMoA belongs to the GB 3077 standard grade and can be used as one of the equivalent steel grades of SAE 4140.The difference in their chemical elements can be seen from the table below.

Grade	C	Si	Mn	P	S	Cr	Mo
4140	0.38-0.43	0.15-0.35	0.75-1.0	≤0.035	≤0.04	0.8-1.1	0.15-0.25
42CrMoA	0.38-0.45	0.17-0.37	0.5-0.8	≤0.035	≤0.035	0.9-1.2	0.15-0.25

Although there are slight differences in the elements, they are all high-strength, wear-resistant and impact-resistant alloy steels, suitable for fields with high performance requirements.

What is 4140 110Ksi?

4140 110Ksi means that after quenching and tempering, the yield strength of 4140 steel must reach a minimum of 110Ksi (758Mpa).

What are the equivalent grades of SAE 4140?

It is precisely because of the wide application of 4140 steel in the manufacturing industry that various countries have developed their own equivalent grades suitable for their own countries.

Europe-EN10083/EN10250	UK-BS970	China-GB 3077	Japan-JIS G4105
42CrMo4/1.7225	708A40 / 708M40	42CrMoA	SCM440

SAE 4140 Steel Physical Property

Density	Specific heat capacity	Poisson's ratio	Elastic Modulus	Shear modulus
7.85 g/cm3	482 (25~100℃)	0.28	211722 Mpa	82473 Mpa
Melting point	Ac1	Ac3	Ar1	Ms
1390℃	730℃	780℃	690℃	360℃

SAE 4140 STEEL FORGING

Initial Forging Temperature：1100℃
Final Forging Temperature： >850℃
Forging Ratio：above 4:1
Post-Forging Treatment:Cooling in sand slowly or furnace cooling after forged.For large sizes of 4140 steel, the recommended method is normalizing or annealing after forging.

SAE 4140 Steel Heat Treatment & Mechanical Property

Normalizing:840-880°C,air cooling
Annealing:800-850°C,furnace cooling
Isothermal Annealing：675°C,furnace cooling
Stress relief Annealing：600-650°C
Quenching:840-880°C,oil/water quench,quenching hardness:55-59HRC
Tempering:550-650°C,hardness:28-32HRC.

SAE 4140 steel Quenching Critical Diameter

	static oil	20°C Water	40°C Water	20°C 5% Sodium chloride solution
Critical Diameter,mm	40	58	54.5	59

Mechanical Property For SAE 4140+QT 80K

	Tensile Strength	Yield Strength	Elongation	Reduction of Area	Impact Charpy-V	Hardness
80K	≥655Mpa(95K)	≥552Mpa(80K)	≥18%	≥35%	≥27(-20ºC)	207-237HBW

Remark:840-860℃ Water quenching,650-670℃ Tempering

SAE 4140 Steel Quality Certification

A material test report(Inspection Certificate EN 10204 3.1) will be provided, documenting the following:
1.Chemical analysis
2.Mechanical properties
3.Surface hardness
4.Non metallic inclusion
5.Heat treatment report
6.Grain size
7.Forging ratio
8.Ultrasonic test report