FAA Aviation Mechanic General (AMG)Materials, Hardware and ProcessesMedium
A repair station needs to identify the type of stainless steel used in a non-magnetic component. A simple field test involves using a magnet. Which series of stainless steel is generally non-magnetic in its annealed condition and commonly used in aircraft for its corrosion resistance?
- A200 series stainless steel
- B400 series stainless steel
- C17-7 PH stainless steel
- D300 series stainless steel
Show answer & explanationAnswer & explanation
Correct answer: D. 300 series stainless steel
The 300 series stainless steels (e.g., 301, 302, 304, 316) are austenitic, meaning they are generally non-magnetic in their annealed condition and are widely used in aircraft for their excellent corrosion resistance.
Why the other options are wrong
- A. 200 series stainless steels are also austenitic and non-magnetic, but less commonly encountered in aircraft than the 300 series for general components.
- B. 400 series stainless steels (e.g., 410, 430) are ferritic or martensitic and are magnetic.
- C. 17-7 PH (Precipitation Hardening) stainless steel is a specialized alloy that is magnetic.
Stainless Steel Series (Aircraft)
Aircraft utilize different series of stainless steel, primarily 300 and 400 series, each with distinct properties regarding magnetism, corrosion resistance, and strength characteristics.
- 300 series (austenitic): Generally non-magnetic, excellent corrosion resistance, not heat treatable for hardness.
- 400 series (ferritic/martensitic): Magnetic, some are heat treatable for strength, good corrosion resistance.
- Common aircraft uses: exhaust systems (300 series), fasteners (400 series).
Memory trick: Three hundred non-magnetic, four hundred attracts.