ThePipingMart Blog Grades AMS 6431 Aircraft Steel – Composition, Properties and Uses

AMS 6431 Aircraft Steel – Composition, Properties and Uses

AMS 6431

AMS 6431 is a type of steel commonly used in the aerospace industry. This steel has specific chemical and mechanical properties, making it a popular choice for producing aircraft parts. This article will discuss the composition, physical and mechanical properties, uses, hardness, and heat treatment of AMS 6431.

What is AMS 6431?

AMS 6431 is a specific steel type commonly used in aerospace and defence industries. AMS 6431 is a high-strength, low-alloy steel with exceptional toughness and durability, making it ideal for critical stress applications. This steel is often used to manufacture landing gear, engine mounts, and other essential infrastructure components for aeroplanes and helicopters. Its properties also make it a popular choice for military equipment and vehicles. So next time you hear the letters AMS 6431, remember it’s not just a code but a top-grade steel that plays a vital role in the aviation and defence industries.

AMS 6431 Composition

AMS 6431 is a low alloy steel with iron, carbon, manganese, molybdenum, and vanadium. The carbon content of AMS 6431 is between 0.08% to 0.14%, which makes it a medium-carbon steel. Adding molybdenum and vanadium enhances the strength and toughness of the steel.

AMS 6431 Physical Properties

AMS 6431 has a density of 7.85g/cm³, the same as other low alloy steel. It has a melting point of 1420-1465°C (2588-2669°F) and thermal conductivity of 46.6W/mK at 100°C temperature. It also has a coefficient of thermal expansion (CTE) of 11.2 µm/m°C.

AMS 6431 Mechanical Properties

AMS 6431 has excellent mechanical properties. It’s Young’s modulus is 200GPa, and its ultimate tensile strength is 1085MPa. It also has a yield strength of 930MPa, and its elongation is 10%.

AMS 6431 Uses

AMS 6431 is most commonly used for producing critical aircraft components like landing gear, shafts, and fasteners. Its high strength and toughness make it an excellent choice for these applications. It is also used in the manufacturing of gas turbines and missile components.

AMS 6431 Hardness

AMS 6431 hardness can be varied from 269 HB to 321 HB by adjusting the heat treatment process. Heat treatment also helps in developing the desired microstructure and optimal mechanical properties.

AMS 6431 Heat treatment

Heat treatment is essential to achieve the desired mechanical properties of AMS 6431. The heat treatment is accomplished by austenitizing at 1650°F for several hours, followed by quenching in oil. The steel is then tempered at temperatures ranging from 300°F to 800°F to achieve the desired properties.


AMS 6431 is a popular choice for producing aircraft components due to its excellent mechanical properties. Its high strength and toughness make it a reliable material for critical applications. Its hardness and heat treatment process can be modified to meet specific requirements. Understanding the chemical and mechanical properties of AMS 6431 is crucial in choosing the suitable material for manufacturing aerospace components.

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