If iron cobalt and nickel are magnetic (which I think is the right term, but it feels wrong since magnets stick but it doesn’t magnet to other steel) then why does using nickel to make stainless steel render steel non-magnetic?
Or is my metallurgical understanding just completely off?
In: Physics
> Or is my metallurgical understanding just completely off?
This is more of a physics question than a metallurgical question.
Metallurgically, stainless steel with high nickel has a different crystal structure than “regular” steel. This crystal structure (austenite) is actually the same one as high temperature steel, which is also not magnetic.
With large simplification (partly because I don’t fully understand the quantum mechanics involved), the spacing of the atoms is different between the 2 crystal structures. This difference is enough that the metal loses ferromagnetism.
Ferromagnetism (aka regular magnetism) basically happens because the spin of atoms’ electrons are aligned with each other. Depending on the distance between atoms and some quantum mechanical properties, atoms will be more-able or less-able to influence the spin if their neighbors.
In “magnetic materials” such as iron and nickel, each atom links up spin to its neighbors, self-reinforcing the magnetic field. In in stainless steel the atoms are spaced enough that the atoms don’t manage to self-reinforce each other.
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