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.
