AMPP Basic Corrosion Certification Practice Exam

Martensitic stainless steels are indeed considered magnetic due to their crystalline structure, which is a result of the iron-based alloy's specific composition, particularly the higher carbon content that promotes the formation of martensite when it undergoes rapid cooling or quenching. This structure has a body-centered tetragonal lattice that retains magnetic properties.

In contrast, austenitic stainless steels, which are more commonly known for being non-magnetic, have a face-centered cubic structure that typically loses magnetic properties due to the higher levels of nickel and chromium they contain, which stabilize the austenitic phase. Martensitic grades, however, do not have this stabilization and therefore exhibit ferromagnetic characteristics even at room temperature.

The other options would suggest conditions or limitations on the magnetic properties that do not apply to martensitic stainless steels. They maintain their magnetic characteristics regardless of the presence of additional alloys or specific temperatures.