ThePipingMart Blog Grades AMS 4157 Aluminum Alloy – Composition, Properties and Uses

AMS 4157 Aluminum Alloy – Composition, Properties and Uses

AMS 4157

Aluminium and its alloys are used in various industries for their lightweight, strength, and corrosion resistance. Among the different alloys, AMS 4157 is a high-strength aluminium alloy widely used in aerospace applications. This alloy is known for its exceptional mechanical and physical properties, making it ideal for critical applications. This blog post will deeply dive into the composition, physical and mechanical properties, uses hardness, and heat treatment of AMS 4157.

What is AMS 4157?

AMS 4157 (also known as 7049 Aluminum Alloy)  is a specification developed by the Society of Automotive Engineers (SAE) that outlines the requirements for a type of hydraulic fluid used in aircraft. This specification is important because it ensures that the fluid meets certain performance criteria, such as resistance to corrosion and oxidation and compatibility with other materials used in aircraft hydraulic systems. Using fluids that meet the AMS4157 specification can help to prevent costly maintenance issues and ensure the safe operation of aircraft. It is worth noting that several other specifications also apply to aircraft /hydraulic fluids, but AMS4157 is one of the most widely recognized.

AMS 4157 Composition

AMS 4157 is an aluminium-magnesium alloy whose composition corresponds to UNS A94157. It contains 5% magnesium and 0.7% chromium and other alloying elements like copper, zinc, iron, and silicon. Adding magnesium and chromium enhances the strength and corrosion resistance of the alloy. The chemical composition of AMS 4157 is tightly controlled to ensure consistency in material properties.

Element Content (%)
Aluminium / aluminum, Al 88.7
Zinc, Zn 7.6
Magnesium, Mg 2.5
Copper, Cu 1.5
Chromium, Cr 0.15

AMS 4157 Physical Properties

AMS 4157 has a density of 2.8 grams per cubic centimetre, slightly less than other aluminium alloys. The alloy can withstand high temperatures and has a melting point of 582°C. It exhibits excellent resistance to corrosion, making it suitable for harsh environments. The coefficient of thermal expansion of AMS 4157 is lower than other aluminium alloys, which means it can handle thermal stress better.

Properties Metric Imperial
Density 2.6-2.8 g/cm3 0.0939-0.1011 lb/in³

AMS 4157 Mechanical Properties

AMS 4157 is known for its excellent mechanical properties, making it ideal for aerospace applications. The alloy has a high strength-to-weight ratio, supporting heavy loads without adding significant weight. It has a yield strength of 550 MPa and a tensile strength of 620 MPa. The alloy also displays good elongation and fracture toughness. Its fatigue strength is also high, making it resistant to crack propagation.

Properties Metric Imperial
Elastic modulus 70-80 Gpa 10152-11603 ksi
Poisson’s ratio 0.33 0.33

AMS 4157 Uses

AMS 4157 is widely used in the aerospace industry for manufacturing aircraft parts, such as landing gear, wing components, and fuselage frames. The alloy is ideal for critical applications that require high strength, low weight, and corrosion resistance. Due to its excellent properties, it is also used in other applications, such as bicycle frames, pressure vessels, and hydraulic components.

AMS 4157 Hardness

AMS 4157’s hardness depends on the heat treatment applied to the alloy. The typical hardness range for AMS 4157 is between 75 and 90 HRB (Rockwell B Scale). However, the hardness can be increased by heat treating the alloy. The alloy can be solution-treated at 520°C and then quenched to improve strength. It can also be aged at 160°C to achieve maximum strength.

AMS 4157 Heat Treatment

AMS 4157 can be heat treated to modify its properties. The alloy can be solution-treated at 520°C for four hours and then water-quenched to achieve maximum strength. After quenching, the alloy is aged at 160°C for up to 20 hours to further increase its strength. The heat treatment process can affect the alloy’s hardness, strength, and flexibility.


AMS 4157 is a high-strength aluminium alloy that finds applications in the aerospace industry. Its chemical composition, physical properties, mechanical properties, uses, hardness, and heat treatment are vital in determining its performance. Engineers and designers can make informed decisions about using AMS 4157 in their applications by understanding these factors. Its strength, low weight, corrosion resistance and good formability make it an excellent choice for many applications.

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