the gradual recrystallization of steel

[George Ezell]

To keep it short:
I read somewhere (heck if I can remember where) that the heat-treatment of steel is temporary, that the stresses put into the blade will slowly "unstress"....
Anyone have a clue as to how long this will take? I've seen pictures of a japanese sword that was 800 years old and still showed a temperline...Maybe I've been mislead.

 

[Guy Thomas]

I'm no metallurgist but I'm fairly certain that only the application of heat or some chemical or electrical reaction would change the basic nature of a heat treated steel.
I've never heard of a blade changing over time, perhaps someone else has. Just my opinion.-Guy Thomas

 

[mikeS]

Steel, is cystaline in nature the hardening process,is a change in the structure. Terms like martensite, auestentite,ferrite, bainite and pearlite refer to the different structures steel may have. These structures depend on time and temp. Ten you can begin to manipulate and change the structures by adding certain alloys.

Some steel will change structure slowly, with the addition of chrome, this happens.
Thats why some makers prefer a 24 hour hold time in their heat treat.
Other manufactures in the steel industry are awarer of this fact also.

I don't believe the hardened and tempered part of the blade will "go away" .

 

[e_utopia]

No, knife steel doesn't lose it's heat-treat over time. However, if you take a piece of steel to full hardness, then don't temper it down to a 'working' Rc, it does build up stress which can damage it (I'm not a Mat. Sci. person, so I don't know exactly what happens, but I do know you're not supposed to store fully-hardened steel for too long).

--JB

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[tom mayo]

no....heat treat transforms steel from austinite molecules into marstinite molecules, complete chemical transformation. cant go back...paul bos can give us a detailed explaination of this...hopefully in words we can understand.

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