Definition
A steel to which one or more elements other than carbon, such as chromium, nickel, molybdenum, vanadium, or manganese, have been added during manufacture to give it specific mechanical properties such as greater strength, hardness, toughness, or resistance to corrosion and heat.
Plain English
Steel that has had extra metals mixed into it to make it stronger, tougher, or more resistant to rust and heat than ordinary steel.
Context Anchor
Seen in aircraft maintenance, especially when discussing bolts, landing gear parts, engine parts, and other components that must handle high loads or wear.
Derivation
Alloy comes from the Old French aloier, meaning 'to combine or mix.' An alloy is a metal made by blending two or more elements together. Alloy steel is therefore steel that has been intentionally mixed with other elements to improve its qualities.
Why Pilots Care
Alloy steels are essential in aviation because they provide the high strength-to-weight ratio needed for safe, durable aircraft structures and components that must withstand extreme stresses.
Intuition Check
Alloy steel does not mean all aircraft steel, and it does not simply mean “very strong steel.” It means steel with specific added elements chosen to give specific properties.
Example Sentence 1
The landing gear struts on this aircraft are made of alloy steel to handle the impact loads of touchdown.
Example Sentence 2
Alloy steel tubing is commonly used in the construction of aircraft landing gear to resist bending under heavy loads.