hardening and rust resistance?

[lc609]

I remember reading an article on the glock by an excellent technical reviewer. He mentioned that the Tenifer finish on the Glock Pistols is a multi step process, with the final step being a nitride bath at 500 deg C which hardens the metal to a depth of several thousandths of a millimeter to 70 on the rockwell scale.

Every one that I have spoken to about the BM 800hss has commented that while the M2 steel should rust, they are having very little problem with rust, even on the unprotected edge. Could hardening M2 to 62-64 rockwell be responsible for this? I remember Tac Knives stating that the M2 blades from BM are hardened to about 62, and that the rockwell scale has is not precise, but rather gives a ball park figure for comarison of relative hardness.

please correct any flaws in my thinking.

pat

 

[lc609]

was it that dumb a question?

 

[Cougar Allen]

No. Harder steel is less prone to rust. My layman's explanation is the atoms are clinging to each other tighter so they're less prone to be seduced into an affair with an oxygen atom. My explanation for it might give a metallurgist laughing fits, but it's a well-known phenomenon.

Of course if you're comparing different alloys there are other factors involved, but if you compare two pieces of the same steel the one that's heat-treated harder is always more rust-resistant. Try annealing an old file and putting it in your toolbox next to your other files -- you'll find it rusts in no time.

-Cougar Allen :{)