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Need an explanatin - steel in freezer
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Bigfattyt
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Patrice Lemée;10733666 said:Even a Beefcake?
Especially a BeefCake! Every one knows BeefCake has to reach at least 230 degrees for 10 minutes to be safe to eat.
You could technically cook a cake at 180 degrees, if you left it in for long enough. You would just likely not have a very tasty cake shaped brick to eat. That temp is enough to cook meat (internal temp), and eventually the cake will dry out and be solid!
It is interesting that the steel warped at what I would consider to be pretty average temperatures.
-23 to a room temperature table with crazy warping would strike me as weird as well.
I understand warping when putting a hot pan under cold water. I would also understand putting a cold piece of steel on a very hot table. But I doubt, even in summer the table top was super hot. Even in direct sunlight.
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Only if he's LUCKY! Folks would pay good money to see that.
Tai Goo
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Folks would pay good money to see that.
... It would be worth it!
Science marches on...
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Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
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The conversion is not continuous. It starts at the Ms and stops at Mf. Most steels we use have a Mf well above room temp. In O-1, virtually all conversion happens between 400F and 200F. Once past the Mf, any austenite becomes retained austenite (RA). The amount of RA in O-1 is nearly 0. Any that stayed would not convert until a very low temp, around -90F. Between 200F and -90F little will be happening. At -300F the carbides undergo some conversion. That temp is cryo. refrigerators and such won't get that cold. -90F is sub-zero quench. Refrigerators don't get that low either.
I'm also not wanting your question to re-start the refrigerator topic, so I'll just say that no quantitative internal changes occurin most steels between 70F ( room temp) and 0F (top grade home freezer), or even -30F ( top grade commercial deep freezer).
I'm also not wanting your question to re-start the refrigerator topic, so I'll just say that no quantitative internal changes occurin most steels between 70F ( room temp) and 0F (top grade home freezer), or even -30F ( top grade commercial deep freezer).
So that would mean that even the -78 dry ice and acetone cryo would be pointless. That's good to know so I don't waste my time.
Thanks
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Okay, here's my theory. There was already stress in the metal based upon his need to straighten them out after quench. The termpering process did not remove the stress entirely. When they underwent the freezing and uneven thawing, it released the stress in the metal resulting in warpage.
That's about all the BS I can muster, since I know nothing about metallurgy.
Tai Goo
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My theory is that Ed's and the Wolfy's methods don't mix well. 
... and as an effect some kind of cosmic vibrational anomaly occurred, most likely due to a quirk or a bleep in the predestined destiny of the planetary alignment at the moment of wrapage.
It created a counter harmonic morphic field in the time/space fabric and universal continuity from a quantum multiversal perspective...
I'm sticking with that.
... and as an effect some kind of cosmic vibrational anomaly occurred, most likely due to a quirk or a bleep in the predestined destiny of the planetary alignment at the moment of wrapage.
It created a counter harmonic morphic field in the time/space fabric and universal continuity from a quantum multiversal perspective...
I'm sticking with that.
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For what it's worth, this was a 3/32 blade that was profiled only. the only grinding I did was to put the 45 degree bevel on the edge.
There wasn't necessairly a need to straighten during tempering. I do that with all my large knives just to make sure they are dead flat. I did, however have to straighten by hand immediately after quenching but the blade was dead on before I put it in the tempering oven.
There wasn't necessairly a need to straighten during tempering. I do that with all my large knives just to make sure they are dead flat. I did, however have to straighten by hand immediately after quenching but the blade was dead on before I put it in the tempering oven.
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What was your pre-HT regime?
Notice I said it's continuous, but non-linear, between Ms and Mf
bladsmth said:
The Mf for high carbon steels are well below zero. That's why sub-zero quench works.
I second Greg's wish you'd done proper RC testing in and around the bends prior to straightening.
I noticed in the Initial post you didn't mention the quenching medium or procedure, was this a full submerge and in a 7, 11, or unknown-second quench? Nose down, horizontal, partial or interrupted--and was the blade allowed to stay submerged until cool enough to handle or was it brought back out still at the 200-400 range before tempering.
It could very well be that the twists took place at areas with bad grain borders, causing plastic deformation, and thus without internal structural shift.
I was playing with some hardened 1/16th thick 15n20 one day, just practicing grinds, and keeping the blade cool as I worked--switching from 80grit blaze to 120 and 220 J-flex (Klingspor) and finally a 400 trizact. I put it down for a dinner break only to return and find it bowed--the entire 6" length (3" blade, 3" working handle) was a lovely little arch--maybe an 1/8th, with two twists.
Even though I had not seen any color shift inf the steel while grinding, the reasons for the warped places was fairly obvious--even though I'd been gone for all of maybe an hour and a half, a slight oxide had formed on the surface, the darkest areas of the light brown spots highlighted deep 80 scratches I'd missed--the worst had been face down on the metal work bench--right at the ricasso and deep enough to catch a trocar probe. The warps in the blade were nearly parallel to each other on opposite sides (one closer to the ricasso by a 1/8") although one was significantly deeper at edge and the other at spine, and from the evidence was able to deduce that not only were those deep gouges the fulcrum of the warps, but the weakest spots as they'd been brought above temper, and identified by how the rust smut started to form in those areas whereas the straight sections were still bright and shiny.
My first Thread on BF was on a weird crack I had in 1095--it was 1/16" crack that only formed on one side of the spine, on the opposite side there was no evidence of damage, and breaking the blade only showed fine grain except in that spot. Drove me nuts--along with some of the kind folks who've contributed to this thread--and to no avail--I hadn't simply over cooked it, but the answer came later from a friend who showed me a pic he'd taken the night I'd normalized the blade.
During the final normalization, I'd put the blade down on my anvil with just that tiny spot closest to the edge...and the tip of my tongs.
The opposing side of the spine had cooled with the rest of the blade thanks to the anvil's thermal conductivity, but just that 1/4" gap between the hot tongs and the blade at that vertices was enough to slow down how that exact spot cooled as opposed to the rest of the knife. I had bad grain structure in that one spot, and thanks to the clay coating, arrested resetting that spot as the blade's edge came up to heat...at quench the effect was like two buses colliding head-on. The crumple zone cracked as the steel contracted, think of it like when you whip your head around too fast and get a crick--when the blade got a crick in its "neck" the crack formed where the "muscle" got pinched during contraction.
As a teacher, your scientific method (experimentation set up) is flawed:
The refrig debate is often focused on 5XXX steels, primarily 52100 and 5160, the Chromium and Vanadium content in 01 is significantly different.
You needed at least two more sets of blades to match the ones you made (same grinds and shapes) and went into the freezer--ones for normal HT to be tested as a control, and then ones used as a variable, say one set to go in the refrigerator (not freezer) and another set to be BY cryoed.
To avoid such factors as differential temperatures--such as being laid flat on a surface--you should have them in some sort of rack standing edge up, or hanging--this way nothing can be accused of influencing how they came back to room temp.
How did you check temp in the freezer? Placement and different temp zones are variables that will be questioned and preplanned.
RC checking for edge consistency--if a heel is at 48RC and the tip at 61, plastic deformation can occur without phase shift. Likewise Spine hardness is a factor--if the blades were differentially (edge) quenched, are you sure you didn't autotemper parts of the blade.
I noticed in the Initial post you didn't mention the quenching medium or procedure, was this a full submerge and in a 7, 11, or unknown-second quench? Nose down, horizontal, partial or interrupted--and was the blade allowed to stay submerged until cool enough to handle or was it brought back out still at the 200-400 range before tempering.
It could very well be that the twists took place at areas with bad grain borders, causing plastic deformation, and thus without internal structural shift.
I was playing with some hardened 1/16th thick 15n20 one day, just practicing grinds, and keeping the blade cool as I worked--switching from 80grit blaze to 120 and 220 J-flex (Klingspor) and finally a 400 trizact. I put it down for a dinner break only to return and find it bowed--the entire 6" length (3" blade, 3" working handle) was a lovely little arch--maybe an 1/8th, with two twists.
Even though I had not seen any color shift inf the steel while grinding, the reasons for the warped places was fairly obvious--even though I'd been gone for all of maybe an hour and a half, a slight oxide had formed on the surface, the darkest areas of the light brown spots highlighted deep 80 scratches I'd missed--the worst had been face down on the metal work bench--right at the ricasso and deep enough to catch a trocar probe. The warps in the blade were nearly parallel to each other on opposite sides (one closer to the ricasso by a 1/8") although one was significantly deeper at edge and the other at spine, and from the evidence was able to deduce that not only were those deep gouges the fulcrum of the warps, but the weakest spots as they'd been brought above temper, and identified by how the rust smut started to form in those areas whereas the straight sections were still bright and shiny.
My first Thread on BF was on a weird crack I had in 1095--it was 1/16" crack that only formed on one side of the spine, on the opposite side there was no evidence of damage, and breaking the blade only showed fine grain except in that spot. Drove me nuts--along with some of the kind folks who've contributed to this thread--and to no avail--I hadn't simply over cooked it, but the answer came later from a friend who showed me a pic he'd taken the night I'd normalized the blade.
During the final normalization, I'd put the blade down on my anvil with just that tiny spot closest to the edge...and the tip of my tongs.
The opposing side of the spine had cooled with the rest of the blade thanks to the anvil's thermal conductivity, but just that 1/4" gap between the hot tongs and the blade at that vertices was enough to slow down how that exact spot cooled as opposed to the rest of the knife. I had bad grain structure in that one spot, and thanks to the clay coating, arrested resetting that spot as the blade's edge came up to heat...at quench the effect was like two buses colliding head-on. The crumple zone cracked as the steel contracted, think of it like when you whip your head around too fast and get a crick--when the blade got a crick in its "neck" the crack formed where the "muscle" got pinched during contraction.
As a teacher, your scientific method (experimentation set up) is flawed:
The refrig debate is often focused on 5XXX steels, primarily 52100 and 5160, the Chromium and Vanadium content in 01 is significantly different.
You needed at least two more sets of blades to match the ones you made (same grinds and shapes) and went into the freezer--ones for normal HT to be tested as a control, and then ones used as a variable, say one set to go in the refrigerator (not freezer) and another set to be BY cryoed.
To avoid such factors as differential temperatures--such as being laid flat on a surface--you should have them in some sort of rack standing edge up, or hanging--this way nothing can be accused of influencing how they came back to room temp.
How did you check temp in the freezer? Placement and different temp zones are variables that will be questioned and preplanned.
RC checking for edge consistency--if a heel is at 48RC and the tip at 61, plastic deformation can occur without phase shift. Likewise Spine hardness is a factor--if the blades were differentially (edge) quenched, are you sure you didn't autotemper parts of the blade.
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It was edge quenched with a full submerge in peanut oil, which would be medium to slow quench. If I recall, I should have thought of this sooner, the blade slipped out of the tongs during the quench and layed flat for a couple of seconds while I was fishing it out. If I remember correctly, I put it in, count to 7, pull it out to check - everything OK, put it back in and drop it, then fish it out and see the warp, straighten it, and put it back in to finish cooling.
That could explain why it bowed. So would I have to requench it or is it good to go as is?
That could explain why it bowed. So would I have to requench it or is it good to go as is?
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Yeah, the "dropped it" part could be the problem... lol.
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