ThePipingMart Blog Grades AMS 6409 Alloy Steel – Composition, Properties and Uses

AMS 6409 Alloy Steel – Composition, Properties and Uses

AMS 6409

Aerospace Material Specifications (AMS) are essential in the aviation industry. These standards are developed by the Society of Automotive Engineers (SAE) and establish a set of requirements for the materials used in aerospace applications. One such material, SAE- AMS 6409, is commonly used in aircraft construction. But what exactly is it? In this blog post, we’ll dive into the composition, physical and mechanical properties, uses, hardness, and heat treatment of AMS 6409.

What is AMS 6409?

AMS 6409 (also known as SAE – AISI 4340 Alloy Steel) is a type of steel that is incredibly strong and resistant to corrosion, making it a popular choice for airplane parts and other high-stress applications. But why is it so special? AMS6409 metal contains a unique combination of elements, including chromium, molybdenum, and nickel, which give it exceptional properties. Although it can be difficult to work with, the benefits of using AMS6409 metal outweigh the challenges. This alloy is essential for keeping aeroplanes and their passengers safe from landing gear to engine components.

What Form is AMS 6409 Available at Piping Mart?

  • Alloy Steel AISI 4340 Bars

AMS 6409 Composition

AMS 6409 steel tubes is a high-strength, low-alloy steel. The composition of this material includes carbon, manganese, silicon, nickel, chromium, molybdenum, vanadium, and tungsten. These elements work together to provide the material with its strength, toughness, and resistance to corrosion.

Element Content (%)
Iron, Fe 95.195 – 96.33
Nickel, Ni 1.65 – 2.00
Chromium, Cr 0.700 – 0.900
Manganese, Mn 0.600 – 0.800
Carbon, C 0.370 – 0.430
Molybdenum, Mo 0.200 – 0.300
Silicon, Si 0.150 – 0.300
Sulfur, S  0.0400
Phosphorous, P  0.0350

AMS 6409 Physical Properties

AMS 6409 has a density of 7.85 g/cm³, a melting point of 1420-1460°C, and a thermal conductivity of 24.2 W/(m*K). This steel also has excellent resistance to fatigue and stress corrosion cracking, which makes it a popular choice in the aerospace industry.

Properties Metric Imperial
Density 7.85 g/cm3 0.284 lb/in³
Melting point 1427°C 2600°F

AMS 6409 Mechanical Properties

The mechanical properties of AMS 6409 sheet are impressive. It has a minimum tensile strength of 160 ksi (1103 MPa) and a minimum yield strength of 145 ksi (1000 MPa). Additionally, it has a high modulus of elasticity, which means it can withstand deformation under stress without breaking.

Properties Metric Imperial
Tensile strength 745 MPa 108000 psi
Yield strength 470 MPa 68200 psi
Bulk modulus (typical for steel) 140 GPa 20300 ksi
Shear modulus (typical for steel) 80 GPa 11600 ksi
Elastic modulus 190-210 GPa 27557-30458 ksi
Poisson’s ratio 0.27-0.30 0.27-0.30
Elongation at break 22% 22%
Reduction of area 50% 50%
Hardness, Brinell 217 217
Hardness, Knoop (converted from Brinell hardness) 240 240
Hardness, Rockwell B (converted from Brinell hardness) 95 95
Hardness, Rockwell C (converted from Brinell hardness. Value below normal HRC range, for comparison purposes only) 17 17
Hardness, Vickers (converted from Brinell hardness) 228 228
Machinability (annealed and cold drawn. Based on 100 machinability for AISI 1212 steel.) 50 50

AMS 6409 Equivalents

AMS 6359 AMS 6454 ASTM A331 (4340) ASTM A711 SAE J1397 (4340)
AMS 6409 ASTM A29 (4340) ASTM A506 (4340) ASTM A752 (4340) SAE J404 (4340)
AMS 6414 ASTM A320 (L43) ASTM A519 (4340) ASTM A829 SAE J412 (4340)
AMS 6415 ASTM A322 (4340) ASTM A646 (4340-7) MIL S-5000

AMS 6409 Specifications

Country USA Britain Britain Japan
Standard ASTM A29 EN 10250 BS 970 JIS G4103
Grades 4340 36CrNiMo4/
EN24/817M40 SNCM 439/SNCM8

AMS 6409 Uses

AMS 6409 bars is commonly used in the construction of critical aerospace components such as landing gear, aircraft engine components, and structural parts. It is also used in other demanding applications requiring high strength and wear and tear resistance.

AMS 6409 Hardness

The hardness of AMS 6409 steel wire is measured using the Rockwell C scale. Due to its high strength, this steel has a hardness of 38 HRC, making it incredibly durable and resistant to wear.

AMS 6409 Heat Treatment

Heat treatment is an essential process used to modify the properties of AMS 6409 material. This steel can undergo quenching and tempering, improving its strength and toughness. The process of quenching involves rapidly cooling the material, while tempering involves heating it to a specific temperature and holding it there for a set amount of time. These treatments can be used together or separately based on the desired properties.


In conclusion, AMS 6409 is a high-strength, low-alloy steel that is commonly used in the aerospace industry. It has impressive physical and mechanical properties, including resistance to fatigue and stress corrosion cracking. It is a popular choice in the construction of aircraft engine components, landing gear, and structural parts. With proper heat treatment, the material’s properties can be further improved, making it an even more desirable choice for aerospace applications. Overall, AMS 6409 is an excellent material to consider for any aircraft construction project.

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