SCM420 Alloy Steel

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Heat Treatment
Cold Processing
Hot Working

SCM420 Alloy Steel

SCM420 Alloy Steel

SCM420 Alloy Steel

SCM420 steel is one of popular alloy steel used as engineering steel. Fushun Specialsteel is one of leading supplier of SCM420 steel materials in reliable quality.

 

SCM420 Steel one steel grade in JIS standard. SCM420 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 SCM420 steel is higher, no temper brittleness. The weldability of SCM420 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 SCM420 steel bar

SCM420 Steel Round Bar: diameter 8mm – 1000mm

SCM420 Steel Plate: thickness 10mm – 1500mm  x width 200mm – 3000mm

SCM420 Steel Grade Square: 20mm – 500mm

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

 

International Comparison of Materials

EU
EN
INTER  ISO USA
AISI
JAPAN
JIS
GERMANY
DIN
CHINA
GB
FRANCE
AFNOR
ITALY
UNI
25CrMo4 25CrMo4 4130 SCM420 25CrMo4 30CrMn 25CD4 25CrMo4(KB)

 

SCM420 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 SCM420

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.

 

Conditions of heat treatment

Annealing: 850℃ Furnace Cooling

Normalization: 850~900℃ Air Cooling

Hardening: 850~900℃ 1st Oil Cooling, 800~850℃ 2rd Oil Cooling

Tempering: 150~200℃ Air Cooling

 

Criterion for heat treating conditions revise:

Ac: 770~835℃

Ar: 770~700℃

Ms: 410℃

 

Mechanical properties

Tensile strength (kgf/mm²): ≧95
Elongation (%): ≧14
Cross section reduction rate (%): ≧40
Impact value (J/cm2): ≧6
Hardness (Hb) : 352~362

 

Application of SCM420 Alloy Steel

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