Sep 27 2012
Topics Covered
IntroductionChemical CompositionPhysical PropertiesMechanical PropertiesThermal PropertiesOther Designations
Introduction
Alloy steels comprise a wide variety of steels with compositions that exceed the limitations of Si, Va, Cr, Ni, Mo, Mn, B and C allocated for carbon steels. These steels have elements such as chromium, cobalt, nickel, etc.
In comparison with carbon steels, alloy steels are more responsive to mechanical and heat treatments. Alloy steels can be used in specific melting and deoxidization processes for particular applications.
The following datasheet provides an overview of AISI 8720 alloy steel.
Chemical Composition
The chemical composition of AISI 8720 alloy steel is outlined in the following table.
| Element |
Content (%) |
| Iron, Fe |
96.895-97.97 |
| Manganese, Mn |
0.700-0.900 |
| Nickel, Ni |
0.400-0.700 |
| Chromium, Cr |
0.400-0.600 |
| Molybdenum, Mo |
0.200-0.300 |
| Carbon, C |
0.180-0.230 |
| Silicon, Si |
0.150-0.300 |
| Sulfur, S |
≤ 0.0400 |
| Phosphorous, P |
≤ 0.0350 |
Physical Properties
The following table shows the physical properties of AISI 8720 alloy steel.
| Properties |
Metric |
Imperial |
| Density |
7.85 g/cm3 |
0.284 lb/in³ |
Mechanical Properties
The mechanical properties of AISI 8720 alloy steel are displayed in the following table.
| Properties |
Metric |
Imperial |
| 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 |
| Hardness, Brinell (hot rolled and cold drawn) |
179-235 |
179-235 |
| Hardness, Knoop (converted from Brinell hardness) |
229 |
229 |
| Hardness, Rockwell B (converted from Brinell hardness) |
93 |
93 |
| Hardness, Rockwell C (converted from Brinell hardness, value below normal HRC range, for comparison only) |
15 |
15 |
| Hardness, Vickers (converted from Brinell hardness) |
217 |
217 |
| Machinability (hot rolled and cold drawn. Based on 100 machinability for AISI 1212 steel) |
65 |
65 |
Thermal Properties
The thermal properties of AISI 8720 alloy steel are given in the following table.
| Properties |
Metric |
Imperial |
| Thermal conductivity (typical steel) |
46.6 W/mK |
323 BTU in/hr.ft².°F |
Other Designations
Equivalent materials to AISI 8720 alloy steel are:
- ASTM A322
- ASTM A331
- ASTM A505
- ASTM A519
- SAE J404
- SAE J770