Jun 20 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Applications
Introduction
Alloy steel is steel alloyed with different elements in total amounts between 1 and 50% by weight to enhance its mechanical properties such as strength, hardness, toughness and wear resistance. Low-alloy steels, on the other hand, are used to achieve better hardenability, which in turn enhances other mechanical properties.
AISI 4140H is an H-steel grade alloy steel, commonly called AISI 4140H chromium-molybdenum steel. The following datasheet will provide an overview of AISI 4140H alloy steel.
Chemical Composition
The chemical composition AISI 4140H alloy steels is outlined in the following table.
|
Element |
Content (%) |
|
Iron, Fe |
96.585 - 97.93 |
|
Chromium, Cr |
0.75 - 1.2 |
|
Manganese, Mn |
0.65 - 1.1 |
|
Carbon, C |
0.37 - 0.44 |
|
Molybdenum, Mo |
0.15 - 0.3 |
|
Silicon, Si |
0.15 - 0.3 |
|
Sulfur, S |
≤0.040 |
|
Phosphorous, P |
≤0.035 |
Physical Properties
The following table shows the physical properties of AISI 4140H alloy steels.
|
Properties |
Metric |
Imperial |
|
Density |
7.85 g/cm3 |
0.284 lb/in3 |
Mechanical Properties
The mechanical properties of AISI 4140H alloy steels are displayed in the following table.
|
Properties |
Metric |
Imperial |
|
Tensile strength |
1150 MPa |
167000 psi |
|
Yield strength |
1050 MPa |
152000 psi |
|
Modulus of elasticity |
205 GPa |
29700 ksi |
|
Bulk modulus |
140 GPa |
20300 ksi |
|
Shear modulus |
80 GPa |
11600 ksi |
|
Poisson’s ratio |
0.29 |
0.29 |
|
Elongation at break |
17.50% |
17.50% |
|
Reduction of area |
55% |
55% |
|
Hardness, Brinell |
341 |
341 |
|
Hardness, Vickers |
361 |
361 |
|
Hardness, Knoop |
369 |
369 |
|
Hardness, Rockwell C |
37 |
37 |
|
Hardness, Rockwell B |
99 |
99 |
Thermal Properties
The thermal properties of AISI 4140H alloy steels are given in the following table
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient (@0-100°C/32-212°F) |
12.2 µm/m°C |
6.78 µin/in°F |
|
Thermal conductivity |
42.6 W/mK |
296 BTU.in/hrft².°F |
Other Designations
Other designations that are equivalent to AISI 4140H alloy steels include the following.
-
B.S. 708 A 42
-
B.S. 708 M 40
-
B.S. 709 M 40
-
ASTM A304
-
SAE J1268
-
SS 2244
-
JIS SCM 4
-
JIS SCM 4 H
-
DIN 1.7225
-
AFNOR 42 CD 4
-
UNI 40 CrMo 4
-
UNI 38 CrMo 4 KB
Applications
The following are the list of applications of AISI 4140H alloy steels:
-
Oil industry
-
Automotive gears
-
Crank shafts
-
Gun barrels
-
Steering knuckles