warped ats34

[butcher_block]

well i had a hunter type in ats34
i got rid of the warp how ever i now have a little crack:grumpy:
i shall make the best of this by asking if the brake looks ok so far as grain and the way it broke
the blade did bend all but 1/2 inch over a 7 inch span before letting go
the warp was maybe 1/16 over the blade but i couldnt leave it go
if need be i can keep braking the blade to have more a view if anyone thinks this would be helpfull
thanks
butch harner

 

[mete]

Not quite sure why the one side has those series of curves on the fracture surface. It's easier to avoid warping instead of trying to straighten. I would only straighten hot , at the tempering temperature . Please give details of the entire heat treating procedure . Many smiths are now plate quenching such alloys which will avoid warping.

 

[Dan Gray]

I shy a way from doing it out of the temper , that scares me, thought guys do it I'm told.. ..
you can straighten it right out of the quench also just don't wait to long
,, glove hot..it's the way I've done it
yes yes On the plate quench:thumbup:

 

[DAMNENG]

I used to warp about 1 in 6 of my AST-34 blades when I heat treated them until I started doing a 10 minute soak at 1480°F before austenizing.

Jim Arbuckle

 

[butcher_block]

the heat teat was done as ramp to 1480 10 min ramp full to 1950 i think 20 min is what i used for time
getto oil quench just had to try in packet oil quench
temper was 450 x2 x2 hours
i now plan on taking it to a friend to get it hardness tested
the other blade i had in did not warp
mete i will also brake a few more time to see how it looks down the rest of the blade
all told i realy couldnt belive how far it bent before letting go and boy did it let go
so looks like im going to stop playing around and get some plates seeing how i have the kiln i guess also Ln is soon comming to my shop
so mete im thinnking 1 inch aluminum or 3/4 inch copper seeing how i ll just be buying them once might as well get nice ones
thanks all and when i get back to the house on sun i ll brake and take pictures
butch

 

[jhiggins]

Not quite sure why the one side has those series of curves on the fracture surface. It's easier to avoid warping instead of trying to straighten. I would only straighten hot , at the tempering temperature . Please give details of the entire heat treating procedure . Many smiths are now plate quenching such alloys which will avoid warping.

I'm so happy with my plate quenching! I love it. The only time there is a chance of warpage is if the blade has not been destressed before the HT, or if the blade has been ground too thin, The plates can't straighten a ripple in your edge.

 

[Dan Gray]

The plates can't straighten a ripple in your edge.

sure it can
press the edge and hold the rest

I've never had this problem with SS,,, Carb is another story though


butch
if it bent a long ways , your in the ball park anyway, try bending a
soft piece and compair..it might make it 30deg's

edited to add
1 or 3/4 inch aluminum will do fine

 

[DAMNENG]

the heat teat was done as ramp to 1480 10 min ramp full to 1950 i think 20 min is what i used for time
getto oil quench just had to try in packet oil quench
temper was 450 x2 x2 hours
i now plan on taking it to a friend to get it hardness tested
the other blade i had in did not warp
mete i will also brake a few more time to see how it looks down the rest of the blade
all told i realy couldnt belive how far it bent before letting go and boy did it let go
so looks like im going to stop playing around and get some plates seeing how i have the kiln i guess also Ln is soon comming to my shop
so mete im thinnking 1 inch aluminum or 3/4 inch copper seeing how i ll just be buying them once might as well get nice ones
thanks all and when i get back to the house on sun i ll brake and take pictures
butch

1950°F for austenize might be a bit high. I have found that 1880°F and forced air quench produces HRC of around 64 as quenched with a 350°F post quench temper. I usually throw the blades in the oven as soon as they are cool enough to touch but not hold with the bare hand. After an hour I pull them out let them cool to room temp then in the freezer to squeeze out the retained austenite. Next day, out of freezer, room temp, then back in the oven twice more, for a tripple temper.

On a different note, you might try hitting your pin holes with a countersink prior to heattreating to cut down on stress risers! From your photos, it looks like this might be where the crack originated.

Jim Arbuckle

 

[Dan Gray]

1950°F for austenize might be a bit high. I have found that 1880°F and forced air quench produces HRC of around 64 as quenched with a 350°F post quench temper. I usually throw the blades in the oven as soon as they are cool enough to touch but not hold with the bare hand. After an hour I pull them out let them cool to room temp then in the freezer to squeeze out the retained austenite. Next day, out of freezer, room temp, then back in the oven twice more, for a tripple temper.

On a different note, you might try hitting your pin holes with a countersink prior to heattreating to cut down on stress risers! From your photos, it looks like this might be where the crack originated.

Jim Arbuckle

Jim
what kind of freezer? L/Nitrogen? I hope so so that won't bring that up here again
I use 1950°F with 154CM and it would be close to the same for ATS34, though once the edge hits that temp (1950) it gets, plated, ..and a bit of air at the edges..,, at that point I don't care about the spine as long as the edge got it's soak at the right temp,
nothing wrong with your snap tempering it.

 

[DAMNENG]

Jim
what kind of freezer? L/Nitrogen? I hope so so that won't bring that up here again
I use 1950°F with 154CM and it would be close to the same for ATS34, though once the edge hits that temp (1950) it gets, plated, ..and a bit of air at the edges..,, at that point I don't care about the spine as long as the edge got it's soak at the right temp,
nothing wrong with your snap tempering it.

Dan

The freezer is a Sears Coldspot.
I would love to do a cyrogenic treatment, but I haven't been able to force myself to spend the $450 plus to buy a decent dewar! The freezer is running at -20°F. The reasoning for this is that the martensite finish (MF) temperature is below room temperature. If the blade temperature isn't reduced to its MF temp during the quench, it usually contains a load of retained austenite which can under stress, temperature change or if you hold your mouth wrong, will convert to martensite. This martensite is untempered and brittle. I often wonder how many commercial stainless blade hunting knives would survive an hunt where the temperatures dropped well below zero?

Jim A.

 

[Dan Gray]

Dan

The freezer is a Sears Coldspot.
I would love to do a cyrogenic treatment, but I haven't been able to force myself to spend the $450 plus to buy a decent dewar! The freezer is running at -20°F. The reasoning for this is that the martensite finish (MF) temperature is below room temperature. If the blade temperature isn't reduced to its MF temp during the quench, it usually contains a load of retained austenite which can under stress, temperature change or if you hold your mouth wrong, will convert to martensite. This martensite is untempered and brittle. I often wonder how many commercial stainless blade hunting knives would survive an hunt where the temperatures dropped well below zero?

Jim A.

I agree -20 will help but you need at least -120 to finsh the quench though some beg to differ that -90 will do it but LN makes sure of it.
try E-bay for your dewar, I use a lab Dewar one fill lasts just about the right amount of time for up to about 10 blades. I paid $10.00 per fill
I think I paid $175.00 for it about 5 years ago.

 

[mete]

There are two levels of cryo , one at -100F [CO2, dry ice] and -300 F[LN ]. Yes -20F will do something but it's not cryo.

 

[Dan Gray]

There are two levels of cryo , one at -100F [CO2, dry ice] and -300 F[LN ]. Yes -20F will do something but it's not cryo.

Hi Robert
I still need to find that write on the steel company that said at least -120
the piece said dry ice wasn't enough to finish it. it was one of the big outfits too but a long time ago also. maybe they've changed their tune some too. .? but to be sure I'll use the LN..