Jul 8 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Applications
Introduction
Alloy steel contains alloying elements such as aluminum, chromium, copper, titanium, nickel, silicon and manganese in varying amounts to manipulate the properties of steel such as weldability, strength, formability, hardenability and corrosion resistance.
AISI 4320H is a nickel-chromium-molybdenum steel. The following section will discuss about AISI 4320H alloy steel.
Chemical Composition
The chemical composition AISI 4320H alloy steels is outlined in the following table.
Element |
Content (%) |
Iron, Fe |
95.745 - 97.18 |
Nickel, Ni |
1.55 - 2 |
Manganese, Mn |
0.40 - 0.70 |
Chromium, Cr |
0.35 - 0.65 |
Molybdenum, Mo |
0.20 - 0.30 |
Carbon, C |
0.17 - 0.23 |
Silicon, Si |
0.15 - 0.30 |
Sulfur, S |
≤0.040 |
Phosphorous, P |
≤0.035 |
Physical Properties
The following table shows the physical properties of AISI 4320H alloy steels.
Properties |
Metric |
Imperial |
Density |
7.85 g/cm3 |
0.284 lb/in3 |
Mechanical Properties
The mechanical properties of AISI 4320H alloy steels are displayed in the following table.
Properties |
Metric |
Imperial |
Tensile strength |
1505 MPa |
218300 psi |
Yield strength |
1050 MPa |
152000 psi |
Modulus of elasticity |
1225 GPa |
177700 psi |
Bulk modulus |
140 GPa |
20300 ksi |
Shear modulus |
80 GPa |
11600 ksi |
Poisson’s ratio |
0.29 |
0.29 |
Elongation at break |
13.50% |
13.50% |
Reduction of area |
48.20% |
48.20% |
Hardness, Brinell |
429 |
429 |
Hardness, Vickers |
455 |
455 |
Hardness, Knoop |
461 |
461 |
Hardness, Rockwell C |
46 |
46 |
Hardness, Rockwell B |
105 |
105 |
Thermal Properties
The thermal properties of AISI 4320H alloy steels are given in the following table
Properties |
Metric |
Imperial |
Thermal expansion co-efficient (@-18-95°C/-0.4-203°F) |
11.3 µm/m°C |
6.28 µin/in°F |
Thermal conductivity |
44.5 W/mK |
309 BTU.in/hrft².°F |
Other Designations
Other designations that are equivalent to AISI 4320H alloy steels include the following.
-
ASTM A304
-
SAE J1268
-
AMS 6299
Applications
The following are the list of applications of AISI 4320H alloy steels:
-
Heavy-section gears
-
Pinions
-
Other heavy-duty machinery components