ThePipingMart Blog Grades AMS 6418 Aircraft Steel – Composition, Properties and Uses

AMS 6418 Aircraft Steel – Composition, Properties and Uses

AMS 6418

AMS 6418 is one of the popular hot-rolled alloys used in various applications such as aerospace, automotive, and defence industries. This alloy is known for its high strength, excellent fatigue properties, and good welding capability. This blog post will discuss AMS 6418’s composition, physical and mechanical properties, uses, hardness, and heat treatment. So, let’s dive into the details.

What is AMS 6418?

AMS 6418 metal is a type of high-strength, low-alloy (HSLA) steel that is commonly used in aerospace and defence applications. It is known for its excellent strength-to-weight ratio, which makes it ideal for use in aircraft and other weight-sensitive applications. AMS 6418 metal is also highly resistant to corrosion, which is important in applications where the material will be exposed to harsh environments. It is also known for its excellent weldability and formability, making it easy to work with and shape into various components. Overall, AMS 6418 metal is a versatile and reliable material used in various industries for its superior strength and durability.

AMS 6418 Composition

AMS 6418 is a low-alloy steel that contains carbon, manganese, chromium, molybdenum, and vanadium. The carbon content ranges from 0.14% to 0.20%, while manganese ranges from 0.70% to 0.90%. Chromium and molybdenum content gives this alloy excellent corrosion resistance properties. Vanadium improves the strength, toughness, and hardenability of the steel.

AMS 6418 Physical Properties

The density of AMS 6418 is 7.85 g/cm3 (0.284 lb/in³), and its melting temperature is around 1400°C (2550°F). This alloy’s thermal and electrical conductivity is relatively low due to its low carbon content. AMS 6418 has a coefficient of thermal expansion of 11.7 µm/m°C (6.5 µin/in°F) at 20°C (68°F).

AMS 6418 Mechanical Properties

The mechanical properties of AMS 6418 depend on heat treatment and other factors. The ultimate tensile strength of this alloy can range from 1240 MPa (180 ksi) to 1480 MPa (215 ksi), depending on the heat treatment. The yield strength ranges from 1095 MPa (160 ksi) to 1310 MPa (190 ksi), and the elongation ranges from 12% to 16%.

AMS 6418 Uses

AMS 6418 is commonly used in applications that require high strength, toughness, and fatigue resistance. This alloy is used in the aerospace industry to manufacture landing gear, structural components, and engine parts. The automotive industry also uses AMS 6418 to manufacture drive shafts, steering components, and suspension parts. The defence industry uses this alloy to manufacture tank tracks, fasteners, and missile parts.

AMS 6418 Hardness

The hardness of AMS 6418 varies depending on the heat treatment. When the alloy is heat-treated to the ultimate tensile strength of 1240 MPa (180 ksi), the hardness ranges from 30 to 41 HRC. Similarly, when the alloy is heat-treated to the ultimate tensile strength of 1480 MPa (215 ksi), the hardness ranges from 43 to 47 HRC.

AMS 6418 Heat Treatment

AMS 6418 can be heat-treated to achieve desired mechanical properties. The heat treatment process involves austenitizing, quenching, and tempering. The alloy can be austenitized at temperatures ranging from 843°C to 905°C (1550°F to 1660°F), followed by oil quenching. The alloy can be tempered at temperatures ranging from 343°C to 621°C (650°F to 1150°F) to achieve the desired mechanical properties.


AMS 6418 is a low alloy steel with excellent strength, corrosion resistance, and fatigue properties. This alloy is widely used in the aerospace, defence, and automotive industries. By understanding this alloy’s composition, physical and mechanical properties, uses, hardness, and heat treatment, you can choose the right AMS 6418 for your specific application needs.

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