AISI 4118 | DIN 18CrMo4/1.7243 | JIS SCM420

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AISI 4118 | DIN 18CrMo4/1.7243 | JIS SCM420

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ASTM A29 4118 steel is one of popular alloy steel used as engineering steel. Futai steel is one of leading supplier of ASTM 4118 steel materials in reliable quality.

ASTM 4118 Steel one steel grade in ASTM A29 standard. ASTM 4118 steel is one of popular alloy steel used for engineering purpose, like fasteners, high pressure pipe and more advanced carburized parts, such as gear, shaft, etc. which work in the noncorrosive medium and temperature below 250 ℃, working with nitrogen hydrogen mixture in the medium.

The quench-hardening ability of AISI 4118 steel is higher, no temper brittleness. The weldability of AISI 4118 steel is also very good, with excellent machining or cutting properties. The tendency of cold crack formation is very small, but machinability and cold straining plasticity is still good.

Supply Range for AISI alloy 4118 steel bar

4118 Steel Round Bar: diameter 8mm – 1000mm

4118 Steel Plate: thickness 10mm – 1500mm x width 200mm – 3000mm

4118 Steel Grade Square: 20mm – 500mm

Surface Finish: Black, Rough Machined, Turned or as per given requirements.

Steel 4118 Standard and Relevant Specifications

Country	USA	Europe	Japan
Standard	ASTM A29	DIN & BS EN 10084	JIS G4105
Grades	4118	18CrMo4/1.7243	SCM420

4118 Steel Bar Chemical Composition

Standard	Grade	C	Mn	P	S	Si	Cr	Mo
ASTM A29	4118	0.18-0.23	0.70-0.90	0.35	0.35	0.15-0.35	0.4-0.6	0.08-0.15
EN 10084	18CrMo4/1.7243	0.15-0.21	0.60-0.90	0.025	0.035	0.4	0.9-1.2	0.15-0.25
JIS G4105	SCM420	0.18-0.23	0.60-0.85	0.03	0.03	0.15-0.35	0.9-1.2	0.15-0.30

Mechanical Properties of AISI Alloy 4118

Properties	Metric
Tensile strength	517 MPa
Yield strength	365 MPa
Bulk modulus (typical for steel)	140 GPa
Shear modulus (typical for steel)	80.0 GPa
Elastic modulus	190-210 GPa
Poisson’s ratio	0.27-0.30
Elongation at break (in 50 mm)	33.00%
Reduction of area	63.70%
Hardness, Brinell	137
Hardness, Knoop (converted from Brinell hardness)	156
Hardness, Rockwell B (converted from Brinell hardness)	75
Hardness, Vickers (converted from Brinell hardness)	143
Machinability (hot rolled and cold drawn, based on 100 machinability for AISI 1212 steel)	60

Physical properties

Modulus of elasticity [103 x N/mm2]: 210
Density [g/cm3]: 7.85
Thermal conductivity [W/m.K]: 20.0

Forging of ASTM Grade 4118 Steel

Hot forming temperature: 1100-850oC.

AISI 4118 Steel Heat Treatment

Normalizing

Normalizing temperature: 860-900oC.

Hardening

Harden AISI 4118 steel from a temperature of 850-880oC followed by oil or water quenching. Hardness after quenching is 39-47 HRC.

Tempering of 4118 steel

Tempering temperature: 595-700oC.

Application of AISI 4118 Alloy Steel

ASTM 4118 case hardening alloy steels are widely used as gear components of all kind and cog wheels. Open die steel forgings for general engineering purposes. Futai steel are available to supply different size of AISI 4118 steel and is able to supply modified 4118/SCM420/18CrMo4 steel composition according to different requirements.