So, you know that scene from A Christmas Story where the kid licks the frozen pole and his tongue sticks to it? Well the exact same thing will happen here for exactly the opposite reason.
Quenching oil is used for a few reasons. It has a much higher boil point than water, doesn’t splash and pop like water, but mostly because it cools more gently and is less likely to crack or warp the metal.
When you quench something in about-room-temp oil or water the goal is to cool things down to about that very rapidly. Molten slats on the other hand can be 800C or so, and so the goal there is instead to get to that temp (and perhaps stay there for a while). What any of this achieves depends on the specific metal we're playing with (and not just "iron vs copper", but "1080 steel vs S7 steel").
While the medium (i.e., air, vacuum, salt, N2/H2, etc) matters in other ways, the difference is in how fast it cools. At least for what you're asking. Steel (and a few other alloys) get locked into a configuration that makes it much higher strength when it's cooled fast enough. That's what quenching is. OTOH, if you let it cool in air, it has all the time it needs to basically relax into its most natural configuration. That's called annealing and usually softens it.
Also, for those unaware, with gears, you need a combination or a balance between hardness and strength, so they are almost always tempered after the quenching process. Tempering is where they heat the hardened steel back up but not to where it's red hot again, usually around 900°F (the gears in this video are probably around 1700°F before quenching), and then slowly bring it back down to room temperature. This reduces the hardness but removes brittleness by reducing stress in the steel.
I had a coworker who used to work at an Antarctic research station. (Dunno if he worked close to the South Pole but he had a photo of him and his wife at the actual Pole.) He told us that they have something called a "Three Hundred Club"; you sit in the sauna for a good while, then rush outside and jump into the water. Supposedly, the initiate experiences 300 degrees of temperature difference when doing this.
Guess you gotta find something fun to do down there.
I'm surprised how slow it goes. I'm no metallurgist but from watching youtube blacksmith videos I would think you'd have a substantially worse quench on the top layer than the bottom because the oil's already so much hotter when it gets in
On one hand they're probably using a steel that isn't terribly sensitive to the variations they have in temperature of both the oil and the steel itself here. On the other hand the oil probably doesn't change temperature all that much overall either, it's liekly a large enough pool (hidden under the grating) that it can absorb the heat without much heating up, and may have an impeller to stir it around. It might even be pre-heated. Thinking about all this is crucial to the final quality though.
I would think that the temperature difference between red hot steel and boiling oil would be enough to overwhelm the difference between boiling and "cool" oil.
When it comes to hardening steel the lowest temperature you hit during the quenching can be very important, regardless of the temperature difference between that and the temperature you cooled from. Not cool enough usually means an incomplete hardening, which can be hard to impossible to sort out afterwards without having to redo the entire heat-quench cycle.
electronicbovine
I'll be quite disappointed if that wasn't quenched in Gatorade/Brawndo
stonecoldstevebuschemi
treboresque
ColdestOne
It's the quenchiest!
sickbreakfast
Tuttutlookslikerain5
I came here for this!
1525CatDaddyO
#gifsthatendtoosoon
wulfbanger
That's hot
Legrooveth
Super hot
paullyboy1999
Squirrell2000
So hot
lurkyloos
yesdearmetoo
I can smell this post.
PushPullMagnet
A few days later
TallynNyntyg
Grind it to complete a goal.
ClaudBalls
You are the forged in fire champion!
Wholivesinapineappleunderthetree
Wielder of the Secret Flame
p7zjnq9gei9000
Cool gear.
thedill2000
All liquids can quench a thirst once.
Firereika
Asta la vista
neversuitable
This kills the temperature.
Goldmarble
AvsFreak
That makes it hard.
CthulhuIsRisen
Hey, hey! I'm not an "it," I'm a "him"
rockmanx853000
I see you too are familiar with case hardening…
ThisGuyHere
Zioxyl
That's hot
CyberHexx
So, you know that scene from A Christmas Story where the kid licks the frozen pole and his tongue sticks to it? Well the exact same thing will happen here for exactly the opposite reason.
MrHappySmiles
“You need to calm down” -oil bath.
usernamesarenotcomments
"You're acting like your mother"
Oracle547
Rubyrose99
I forgot they'd use oil, hence the fire. Is it to avoid like a bunch of scalding splashes?
jonestown
Different metals require different quenching temperatures and cooling time.
Hurro
I think it has to do with a higher boiling point and insulating to not cool it down too fast.
chefsoda
Quenching oil is used for a few reasons. It has a much higher boil point than water, doesn’t splash and pop like water, but mostly because it cools more gently and is less likely to crack or warp the metal.
Canigetbannedagain2
Water turning to steam has an expansion ration of 1:1700... One part water to 1700 parts steam (at average atmosphere pressure) This might also be a big factor.... https://www.reference.com/science-technology/ratio-water-steam-e8765e4e16144993
ArcaneM37
Thank you! I was wondering how adding water caused combustion. Oil makes perfect sense. And it makes more sense than water for quenching.
honda4wssi9
What did you call me?
CapitalNick
Forbidden cherry-flavored whatever.
EvilEmperorXurg
Metal Gear Solid 6?
rsmgod287
Satisfying
JackieTreehornProductions
what's the difference between doing this vs liquid salt heat treatment which then just air cool?
nemocares
When you quench something in about-room-temp oil or water the goal is to cool things down to about that very rapidly. Molten slats on the other hand can be 800C or so, and so the goal there is instead to get to that temp (and perhaps stay there for a while). What any of this achieves depends on the specific metal we're playing with (and not just "iron vs copper", but "1080 steel vs S7 steel").
cheidiotou
While the medium (i.e., air, vacuum, salt, N2/H2, etc) matters in other ways, the difference is in how fast it cools. At least for what you're asking. Steel (and a few other alloys) get locked into a configuration that makes it much higher strength when it's cooled fast enough. That's what quenching is. OTOH, if you let it cool in air, it has all the time it needs to basically relax into its most natural configuration. That's called annealing and usually softens it.
pookieeatworld
Also, for those unaware, with gears, you need a combination or a balance between hardness and strength, so they are almost always tempered after the quenching process. Tempering is where they heat the hardened steel back up but not to where it's red hot again, usually around 900°F (the gears in this video are probably around 1700°F before quenching), and then slowly bring it back down to room temperature. This reduces the hardness but removes brittleness by reducing stress in the steel.
commentsivehadafew
Going from the sauna into the cold pool
pookieeatworld
I've heard that's really good for your skin, can anyone confirm that?
nasukkin
I had a coworker who used to work at an Antarctic research station. (Dunno if he worked close to the South Pole but he had a photo of him and his wife at the actual Pole.) He told us that they have something called a "Three Hundred Club"; you sit in the sauna for a good while, then rush outside and jump into the water. Supposedly, the initiate experiences 300 degrees of temperature difference when doing this.
Guess you gotta find something fun to do down there.
CobraCommander1981
I would poop.
BlueDsc
That sounds potentially fatal.
nasukkin
Hence the existence of a ceremonial club to celebrate those who undertake the trial!
TrashCanEnthusiast
I'm surprised how slow it goes. I'm no metallurgist but from watching youtube blacksmith videos I would think you'd have a substantially worse quench on the top layer than the bottom because the oil's already so much hotter when it gets in
nemocares
On one hand they're probably using a steel that isn't terribly sensitive to the variations they have in temperature of both the oil and the steel itself here. On the other hand the oil probably doesn't change temperature all that much overall either, it's liekly a large enough pool (hidden under the grating) that it can absorb the heat without much heating up, and may have an impeller to stir it around. It might even be pre-heated. Thinking about all this is crucial to the final quality though.
tgeliot
I would think that the temperature difference between red hot steel and boiling oil would be enough to overwhelm the difference between boiling and "cool" oil.
nemocares
When it comes to hardening steel the lowest temperature you hit during the quenching can be very important, regardless of the temperature difference between that and the temperature you cooled from. Not cool enough usually means an incomplete hardening, which can be hard to impossible to sort out afterwards without having to redo the entire heat-quench cycle.
tgeliot
Huh. TIL.