Steel is one of the most commonly used materials in the manufacturing industry due to its excellent properties, such as durability, strength, flexibility, and machinability. Over the years, steel has undergone several modifications to improve its quality and suitability for various applications. One such type of steel is the AISI 8720H, a low-alloy steel containing chromium and molybdenum. This blog post aims to provide a comprehensive guide to understanding AISI 8720H steel, including its composition, mechanical and physical properties, uses, corrosion resistance, heat treatment, machining, and welding.
AISI 8720H Steel Composition
AISI 8720H steel is a low-alloy steel containing a mixture of alloying elements, including nickel, chromium, and molybdenum. The chemical composition of AISI 8720H steel is as follows: carbon (0.18% to 0.23%), manganese (0.70% to 0.90%), phosphorus (max 0.035%), sulfur (max 0.040%), silicon (0.15% to 0.35%), nickel (0.40% to 0.70%), chromium (0.40 to 0.60%), and molybdenum (0.15% to 0.25%). These alloying elements improve the strength and hardness of the steel, making it ideal for various industrial applications.
| Element | Content (%) |
|---|---|
| Iron, Fe | 96.745-98.18 |
| Manganese, Mn | 0.600-0.950 |
| Nickel, Ni | 0.350-0.750 |
| Chromium, Cr | 0.350-0.650 |
| Molybdenum, Mo | 0.200-0.300 |
| Carbon, C | 0.170-0.230 |
| Silicon, Si | 0.150-0.300 |
| Sulfur, S | ≤ 0.0400 |
| Phosphorous, P | ≤ 0.0350 |
AISI 8720H Steel Mechanical Properties
The mechanical properties of AISI 8720H steel are excellent, making it suitable for applications that require high strength and toughness. The tensile strength of AISI 8720H steel is 925 MPa, with a yield strength of 655 MPa and an elongation of 14%.
| 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) | 15.0 | 15.0 |
| Hardness, Vickers (converted from Brinell hardness) | 217 | 217 |
| Machinability (hot rolled and cold drawn, based on 100 machinability for AISI 1212 steel) | 65 | 65 |
AISI 8720H Steel Physical properties
The physical properties of AISI 8720H steel, including density, thermal conductivity, and electrical conductivity, are similar to those of other low-alloy steels.
| Properties | Metric | Imperial |
|---|---|---|
| Density | 7.85 g/cm3 | 0.284 lb/in³ |
AISI 8720H Equivalents
- ASTM A304
- SAE J1268
AISI 8720H Steel Uses
AISI 8720H steel is used in various industries, including manufacturing, construction, and transportation. It is commonly used to produce gears, shafts, fasteners, and other parts that require high strength and durability. Due to its excellent machinability, AISI 8720H steel is also used to produce machine parts, such as bolts, nuts, and screws.
AISI 8720H Steel Corrosion Resistance
AISI 8720H steel has good corrosion resistance properties, making it suitable for applications where exposure to harsh environments is expected. However, it is not recommended in highly corrosive environments where corrosion can occur rapidly.
AISI 8720H Steel Heat treatment
AISI 8720H steel is heat treatable, and its properties can be altered through heat-treatment processes such as annealing, quenching, and tempering. Heat-treating AISI 8720H steel can improve its strength, hardness, and wear resistance, making it suitable for various applications that require high strength and toughness.
AISI 8720H Steel Machining and Welding
AISI 8720H steel has excellent machinability and can be easily machined into various shapes and sizes. It can be welded using standard welding techniques, including MIG, TIG, and stick welding.
Conclusion:
AISI 8720H is a low-alloy steel commonly used in various industrial applications, including manufacturing, construction, and transportation. It has excellent properties such as high strength, toughness, and machinability. Understanding the composition, mechanical and physical properties, uses, corrosion resistance, heat treatment, machining, and welding of AISI 8720H steel is essential in selecting and applying the material for various applications. With this knowledge, it is possible to optimize the use of AISI 8720H steel in multiple applications, resulting in high-quality and durable products.
Abhishek is a seasoned blogger and industry expert, sharing his insights and knowledge on various topics. With his research, Abhishek offers valuable insights and tips for professionals and enthusiasts. Follow him for expert advice on the latest trends and developments in the metal industry.
