ThePipingMart Blog Grades SAE AMS-S-7720 – Composition, Properties, and Uses

SAE AMS-S-7720 – Composition, Properties, and Uses


AMS-S-7720 is a military specification that people often encounter when dealing with aircraft parts. This specification covers a specific type of steel alloy used in aircraft manufacturing of aircraft. AMS-S-7720 is a high-strength, low-alloy steel known for its excellent mechanical and physical properties. In this article, we will delve deeper into the world of AMS-S-7720 and explore its composition, physical and mechanical properties, uses, hardness, and heat treatment.

What is AMS-S-7720?

AMS-S-7720 is a specification document that defines the requirements for a specific type of adhesive sealant used in aircraft applications. This sealant must meet strict standards for durability, strength, and resistance to temperature changes, moisture, and other environmental factors. It is critical to aircraft construction and maintenance to ensure that all fasteners and joints are securely sealed against leaks and corrosion. Without a high-quality adhesive sealant like AMS-S-7720, aircraft components could quickly fail, leading to potentially catastrophic consequences. As a result, this specification plays a crucial role in ensuring the safety and performance of aircraft worldwide.

AMS-S-7720 Composition

AMS-S-7720 is composed of high-strength, low-alloy steel. Its composition includes carbon, manganese, silicon, sulphur, phosphorus, chromium, molybdenum, and nickel. These elements work together to give AMS-S-7720 its characteristic strength and durability. The alloy is typically melted using vacuum induction (VIM) or air melting methods.

AMS-S-7720 Physical Properties

AMS-S-7720 has a density of approximately 0.284 lb/in³. Its melting point is around 2,780°F (1,527°C). It has a coefficient of thermal expansion of 6.70 x 10^-6 in/in/°F at 68°F (20°C). The thermal conductivity of AMS-S-7720 is also quite high, standing at around 293 BTU in/hr.ft².°F. The material is generally corrosion-resistant, making it ideal for harsh environments.

AMS-S-7720 Mechanical Properties

AMS-S-7720 has excellent mechanical properties, making it ideal for use in the aerospace industry. Its tensile strength is at least 230 ksi (kilo pounds per square inch). Its yield strength ranges from 205 ksi to 220 ksi. The alloy has an elongation of approximately 20%. Its impact strength ranges from 86 flubs to 102 flubs, and its hardness ranges from 28 to 36 HRC. These mechanical properties make AMS-S-7720 an ideal material for aerospace applications, where high strength and durability are paramount.

AMS-S-7720 Uses

AMS-S-7720 is used in various aircraft components, including landing gear, engine mounts, and airframes. Its high strength and durability make it suitable for use in critical parts of an aircraft where failure could be catastrophic. The alloy is also used in the defence and nuclear industries, where high-strength materials are required.

AMS-S-7720 Hardness

AMS-S-7720 has a hardness range of 28 HRC to 36 HRC. The hardness range measures the material’s ability to resist penetration and deformation. The hardness of AMS-S-7720 is critical in determining its strength and suitability for specific applications.

AMS-S-7720 Heat Treatment

AMS-S-7720 is typically hardened through a process known as quenching and tempering. The quenching process involves heating the material to a high temperature and then rapidly cooling it with a medium such as water or oil. The tempering process involves heating the quenched material to a lower temperature, which helps to restore some of its flexibility and prevent brittleness. The heat treatment process helps to improve the material’s mechanical properties, including its strength, toughness, and hardness.


AMS-S-7720 is a high-strength, low-alloy steel commonly used in the aerospace industry. Its characteristics, including its excellent mechanical and physical properties, corrosion resistance, and hardness, make it ideal for use in critical components of an aircraft. The material is also used in other applications, such as the defence and nuclear industries. Heat treatment is an essential process in manufacturing AMS-S-7720, as it helps to improve its mechanical properties further. In conclusion, understanding the properties of AMS-S-7720 is essential in manufacturing durable and safe aircraft components.

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