Magnets

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Vicarious Reality

Joined
Apr 9, 2008
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Does anyone know what a constant strong magnet field does to a knife?
If anything?


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sometimes, it might make it magnetic? i have a couple of cheap blades that have done that.
 
Vicarious Reality said:
Does anyone know what a constant strong magnet field does to a knife?
If anything?
Click to expand...

It... magnetizes it.

Magnetic fields do not affect the crystalline or atomic structure or other cutting-related physical properties of steel. Magnetism is a sub-atomic effect.
 
Imagine a series of signs that look like stop signs, except that they have arrows pointing in a single direction. Now, randomly point these signs in any direction. Looking at the signs as a whole, the arrows just look like a jumbled up mess and don't clearly point anywhere.

Now, imagine that you were to go an re-arrange the signs. You get all of the arrows to point in the same direction. It doesn't change the shape, or the overall organization of the signs as the arrows have nothing to do with how the signs fit against each other.

If you were to measure the poles of a magnet, you would find that the majority of them point in the same direction. Non-magnetic iron/steel is like a jumbled up mass of those arrowed signs. All magnetizing does is re-arrange the poles.
 
Vicarious , you're confused, microstructure is metallurgy but magnetism is physics !!
Actually many knives are already magnetized due to equipment in the knife making process.
 
Last edited by a moderator:
ICP reference.

I know some stainless steels aren't magnetic, but I don't know if that includes any knife steels.
 
I recall reading somewhere that one knife making culture or school of thought quenches blades in a certain compass direction for one reason or another. I believe the thinking goes that quenching the blade towards magnetic north improves the properties of the metal. has anyone else heard or read this?
 
i know that some stainless steels wont hold a magnetic feild. when i worked at home&garden shows i sold proffesional cookware and at some of the higher end restraunts they use a method of cooking called induction. i cant remember what stainless steel it was but shit was expensive (i made good damn money).

back to the point. the stainless steel that i know works is T430 surgical.
but i have never seen a knife in T430.
 
i guess that doesnt really make sense unless you know who induction works.

it works with magnetic feilds to transfer energy.
 
Of the three possible microstructures -ferrite, austenite, martensite, austenite is non-magnetic. Induction heating requires ferrite or martensite.
 
Bumppo said:
I recall reading somewhere that one knife making culture or school of thought quenches blades in a certain compass direction for one reason or another. I believe the thinking goes that quenching the blade towards magnetic north improves the properties of the metal. has anyone else heard or read this?
Click to expand...

Yes I have but I think it generally has to do more with theories of geomancy/superstition (or "magic" if you will) than magnetism. Some Muslims will forge or quench facing Mecca, followers of Chinese Feng Shui principles might face east, depending on the shape of the room, etc.

As magnetism was not well understood for probably millennia after people were working metal I doubt the ancients had a particular insight involving magnetic north.
 
mete said:
Of the three possible microstructures -ferrite, austenite, martensite, austenite is non-magnetic. Induction heating requires ferrite or martensite.
Click to expand...

I don't know about induction for heating, but 300 series SS (austenetic) gets heated to red hot with induction coils in a tube mill
 
I have Spyderco T-Max folder that uses a magnet to stay open. I doubt there are any effects on the blade.
 
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