Sep 13 2012
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Introduction
Alloy steels contain elements such as chromium, cobalt, nickel. They comprise a wide range of steels with compositions that exceed the limitations of Si, Va, Cr, Ni, Mo, Mn, B and C allocated for carbon steels.
Alloy steels are used in specific melting and deoxidization processes for particular kind of applications. When compared to carbon steels, alloy steels are a lot more responsive to mechanical and heat treatments.
The following datasheet provides an overview of AISI 4118 alloy steel.
Chemical Composition
The chemical composition of AISI 4118 alloy steel is outlined in the following table.
Element |
Content (%) |
Iron, Fe |
97.7-98.49 |
Manganese, Mn |
0.70-0.90 |
Chromium, Cr |
0.40-0.60 |
Carbon, C |
0.18-0.230 |
Silicon, Si |
0.15-0.35 |
Molybdenum, Mo |
0.080-0.15 |
Sulfur, S |
0.040 |
Phosphorous, P |
0.035 |
Physical Properties
The following table shows the physical properties of AISI 4118 alloy steel.
Properties |
Metric |
Imperial |
Density |
7.85 g/cm3 |
0.284 lb/in³ |
Mechanical Properties
The mechanical properties of annealed AISI 4118 alloy steel are displayed in the following table.
Properties |
Metric |
Imperial |
Tensile strength |
517 MPa |
75000 psi |
Yield strength |
365 MPa |
52900 psi |
Bulk modulus (typical for steel) |
140 GPa |
20300 ksi |
Shear modulus (typical for steel) |
80.0 GPa |
11600 ksi |
Elastic modulus |
190-210 GPa |
27557-30458 ksi |
Poisson's ratio |
0.27-0.30 |
0.27-0.30 |
Elongation at break (in 50 mm) |
33.00% |
33.00% |
Reduction of area |
63.70% |
63.70% |
Hardness, Brinell |
137 |
137 |
Hardness, Knoop (converted from Brinell hardness) |
156 |
156 |
Hardness, Rockwell B (converted from Brinell hardness) |
75 |
75 |
Hardness, Vickers (converted from Brinell hardness) |
143 |
143 |
Machinability (hot rolled and cold drawn, based on 100 machinability for AISI 1212 steel) |
60 |
60 |
Thermal Properties
The thermal properties of AISI 4118 alloy steel are given in the following table.
Properties |
Metric |
Imperial |
Thermal conductivity (typical steel) |
44.5 W/mK |
309 BTU in/hr.ft².°F |
Other Designations
Equivalent materials to AISI 4118 alloy steel are as follows:.
ASTM A29 |
ASTM A322 |
ASTM A331 |
ASTM A506 |
ASTM A507 |
ASTM A513 |
ASTM A519 |
ASTM A752 |
ASTM A829 |
SAE J404 |
SAE J1397 |
SAE J412 |
ASTM A505 |
SAE J770 |
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