Definition
An alloy steel containing chromium and nickel as its principal alloying elements, valued in aircraft construction for its high strength, toughness, and resistance to corrosion and fatigue. It is commonly used for highly stressed structural parts such as engine mounts, landing gear components, bolts, and shafts.
Plain English
A type of steel that has chromium and nickel mixed into it to make it stronger, tougher, and more resistant to rust than ordinary steel. It is used where parts have to handle heavy loads without breaking or wearing out.
Context Anchor
Seen in aircraft maintenance, repair manuals, material specifications, and parts descriptions.
Derivation
Chrome is short for chromium, from the Greek 'chroma' meaning colour, named because chromium compounds produce vivid colours. Nickel comes from the German 'Kupfernickel' (copper-devil), a miner's name for an ore that looked like copper but yielded none. The name simply tells you the two metals added to the steel.
Why Pilots Care
Knowing that certain parts are made from chrome nickel steel helps a pilot or mechanic understand why specific bolts, fittings, or landing gear components must not be substituted with ordinary hardware-store steel. The strength and fatigue properties matter for safety and airworthiness.
Intuition Check
Do not read chrome here as a shiny surface coating. Chrome nickel steel means chromium and nickel are mixed into the steel itself.
Example Sentence 1
The engine mount bolts are made of chrome nickel steel and must be replaced only with parts of the same specification.
Example Sentence 2
Mechanics selected chrome nickel steel bolts for the firewall attachment points because the alloy holds its strength near the engine.