ThePipingMart Blog Grades AMS 6521 Alloy Steel – Composition, Properties and Uses

AMS 6521 Alloy Steel – Composition, Properties and Uses

AMS 6521

If you are in the engineering or manufacturing industry, you might have encountered AMS 6521 steel alloy. It’s known for its outstanding strength and durability, making it a popular choice in various applications. But what exactly is AMS 6521, and what are its properties and uses? This comprehensive guide will review everything you need to know about AMS 6521 steel alloy.

What is AMS 6521?

AMS 6521 (also known as Maraging Steel 300) is an aerospace material known for its impressive strength and durability. This material is often used in manufacturing high-performance parts for the aerospace industry, where reliability and safety are of utmost importance. But what sets AMS 6521 apart from other aerospace materials is its ability to withstand extreme temperatures and high-stress environments. This makes it a favourite choice among engineers and designers tasked with creating parts that can perform flawlessly under even the most demanding conditions. Whether you are working on a commercial airliner or a spacecraft that will travel to the edges of our solar system, AMS 6521 is a material you can rely on to get the job done.

AMS 6521 Composition

AMS 6521 is a low-alloy steel that contains chromium, manganese, molybdenum, and nickel. Its chemical composition is designed to provide exceptional strength, toughness, and resistance to wear and tear. The steel is typically produced through vacuum melting and electro-slag remelting (ESR) processes to ensure uniformity in the composition.

Element Content (%)
Iron, Fe 67
Nickel, Ni 18.5
Cobalt, Co 9
Molybdenum, Mo 4.8
Titanium, Ti 0.6
Aluminum, Al 0.1
Silicon, Si 0.10
Manganese, Mn 0.10
Carbon, C 0.030
Zirconium, Zr 0.01
Phosphorous, P 0.010
Sulfur, S 0.010
Boron, B 0.0030

AMS 6521 Physical Properties

AMS 6521 steel alloy has a density of 7.85 g/cm³ and a melting point of 1,425°C. Its high hardness level makes it resistant to surface deformation and wear. The steel has excellent corrosion resistance and can withstand high temperatures without losing strength and durability.

Properties Metric Imperial
Density 8.00 g/cm3 0.289 lb/in³
Melting point 1412.8 °C 2575°F

AMS 6521 Mechanical Properties

AMS 6521 has impressive mechanical properties that make it suitable for demanding applications. Its tensile strength ranges from 1700-2100 MPa, and the yield strength is around 1370 MPa. The steel has a high fatigue strength, which means that it can withstand cyclic loading and stress without breaking down. AMS 6521 steel alloy has a good impact resistance property, making it an ideal material for high-impact applications.

Properties Metric Imperial
Tensile strength (@538°C/1000°F) 1158 MPa 168000 psi
Yield strength (@strain 0.200 %, temperature 538°C/@strain 0.200 %, temperature 1000°F) 1056 MPa 153200 psi
Bulk modulus (typical for steel) 140 GPa 20300 ksi
Shear modulus (estimated from elastic modulus) 73.0 GPa 10600 ksi
Elastic modulus 190 GPa 27600 ksi
Poisson’s ratio 0.3 0.3
Elongation at break (in gage length of 4.5 times the square root of the area, @ 316°C/600 °F) 12.00% 12.00%
Reduction of area (@427°C/800°F) 61.30% 61.30%

AMS 6521 Equivalent

Equivalent material to AMS 6521 alloy steel includes DIN 1.6354.

AMS 6521 Thermal Properties

Properties Metric Imperial
Thermal expansion co-efficient (@21-480°C/69.8-896°F) 10.1 µm/m°C 5.61 µin/in.°F
Thermal conductivity (20°C) 25.3 W/mK 176 BTU in/hr.ft².°F

AMS 6521 Uses

AMS 6521 steel alloy has a wide range of uses in different industries. It’s commonly used in the aerospace and defence industry for manufacturing aircraft components, missile and rocket parts, and fasteners. It’s also used in the automotive industry for manufacturing gears, shafts, and wear-resistant components. Additionally, AMS 6521 can be used for making industrial tools like drill bits and cutting blades and manufacturing medical equipment like surgical instruments.

AMS 6521 Hardness

One of the most remarkable properties of AMS 6521 is its high hardness level, which is around 50-55 HRC. It provides exceptional resistance to wear and tear, making it suitable for demanding applications where surfaces undergo repeated wear and impact. The steel’s hardness level can be increased by heat treatment processes like quenching and tempering to further enhance its properties.

AMS 6521 Heat treatment

The heat treatment processes of AMS 6521 steel alloy can significantly affect its properties. Quenching, tempering, annealing, and normalizing are common heat treatment processes that improve the steel’s hardness, toughness, and ductility. The appropriate heat treatment process depends on the steel’s intended use and the desired properties.


In conclusion, AMS 6521 steel alloy is popular for its exceptional strength, durability, and wear resistance. With its excellent mechanical and physical properties, steel is widely used in different industries, including aerospace, defence, automotive, and medical. Understanding its composition, properties, and uses can help you make informed decisions when selecting materials for your manufacturing applications. With proper heat treatment, AMS 6521 can be optimized for specific purposes, making it a versatile and reliable material for various industries.

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