Straightening CPM-154 - How long a Plate Quench?

[TK Steingass]

Hi fellas:

I just broke a CPM-154 Loveless style Big Bear trying to straighten it after tempering it. I had it at 450 degrees and snapped the bugger - I used all the profanity I had in my vocabulary at that moment. In doing research I've read in the threads that one fella does a 10 second plate quench, removes the blade from the stainless foil and straightens it - that it will "bend like butter." I soak at 1950 for 30 minutes, plate quench with forced air and then double temper at 450.

I'm thinking of giving this a try. My question is, is 10 seconds with forced air long enough? I'd like to perform all my straightening prior to my double temper at 450, and at the same time, keep my blood pressure within reasonable limits.

I'd appreciate your insights on this method, or any suggestions on a better way to do it.

Best regards,

TK

 

[mete]

How curved was it ?
You could prevent most of the curve by stress relieving it before HT at 1200 F. That takes care of stress for the original steel and what you added in grinding etc.

 

[Mitchell Knives]

I can't offer many suggestions, as I straighten (if necessary) after tempering.

Are you starting the HT procedure with the blade in a cold oven?

Have you thought about heat treating the blank, then grinding it?

 

[TK Steingass]

How curved was it ?
You could prevent most of the curve by stress relieving it before HT at 1200 F. That takes care of stress for the original steel and what you added in grinding etc.

Mete: Thanks for the reply - the OAL was 14" and it had about a 1/4" bow.(before I snapped it) This sounds like a good approach - maybe stress relieve it while clamped to a hunk of angle iron.

 

[TK Steingass]

I can't offer many suggestions, as I straighten (if necessary) after tempering.

Are you starting the HT procedure with the blade in a cold oven?

Have you thought about heat treating the blank, then grinding it?

Jonathan: Thanks for the reply! Yep, starting it out in a cold oven - HT the blank then grinding is not an option I want to get into because of the expense of all the abrasives I'd go through tapering the tang. I do some grinding on the blade after tempering to get it to finish size though.

 

[Stacy E. Apelt - Bladesmith]

A hold at 1200F for 15-20 minutes is part of any good stainless HT regimen. The blade is in the foil packet at this time, BTW.

I rarely even check my blades as they cool in the quench plates, and they are usually dead straight.

As to straightening directly out of the oven -
Pull the foil packet and plate quench for 10-20 seconds. Forget the forced air, as it may cause problems, not cure them.
Pull the packet out and snip the end. Check for straightness, straightening as needed, and place back in the plates, clamping for five minutes.
Cool to room temp, and then proceed with the cryo and tempering as normal.

 

[TK Steingass]

A hold at 1200F for 15-20 minutes is part of any good stainless HT regimen. The blade is in the foil packet at this time, BTW.

I rarely even check my blades as they cool in the quench plates, and they are usually dead straight.

As to straightening directly out of the oven -
Pull the foil packet and plate quench for 10-20 seconds. Forget the forced air, as it may cause problems, not cure them.
Pull the packet out and snip the end. Check for straightness, straightening as needed, and place back in the plates, clamping for five minutes.
Cool to room temp, and then proceed with the cryo and tempering as normal.

Thanks Stacy!