H/T Question?

[Gary Mulkey]

I ran into something that is beyond me to answer and hopefully one of you can help. I recently heat treated a damascus blade that warped when quenched (Park's 50). When I put it in the oven to temper, it relaxed and straightened which would indicate to me that it had cooled unevenly when quenched. (I had quenched it in a 5 gallon bucket of Park's 50 and adgitated it sideways.)

 

Normally when a blade warps on me I expect it to be unevenly ground but this one seems to be a equal left/right grind. I can understand why a damascus blade might warp but not why it would straighten on tempering. Any ideas why a blade would warp when quenched & straighten when tempered other than possible uneven cooling when quenched?

 

Gary

Edited October 4, 2010 by Gary Mulkey

[sethhoward]

This does not answer your question about why it straightened out but you said agitated sideways? Did you not mean front to back?

 

 

Seth

[kb0fhp]

For a blade I would recommend plunging it downward and agitating it by moving it up and down. As an alternative, you could try ultrasonics for agitation. Back and forth will cause uneven cooling on one side or the other. I would not expect it to relax when tempering unless you put a LARGE weight on it and tempered at a fairly high temperature.

[Mike Blue]

But there are other questions to answer yet. What are your steels in the PW? Sometimes there is enough difference in coefficient of expansion/contraction that movement can occur.

 

What was your pre-heat treatment routine? In this case, what is the heat history of the billet and blade? Did you thermal cycle the blade before quenching?