Quenching 3/8" thick 3v

Darrin Sanders said:
Freezing quench plates is a waste of time and money. These are air hardening steels. Therefore, they will harden in still air. Knifemakers use plates to slightly speed up the process and keep warpage to a minimum.
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FYI, For air hardening steel, faster quench rate will reduce the chance of Cr carbide to precipitate at the grain boundaries which cause embrittlement and reduce corrosion resistance.

And for many type of steel such as AEB-L which also considered as air hardening steel, faster quench like oil does get you higher as quenched hardness compare to air cool.
 
Oil quenching may have some effect but freezing quench plates will make no noticeable difference but if it makes you feel better then have at it.
 
Darrin Sanders said:
Oil quenching may have some effect but freezing quench plates will make no noticeable difference but if it makes you feel better then have at it.
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You say people use plate quench just only to speed up the process and minimal the warpage didn't you?

But actually there are also the reason of faster quench will give better steel structure even for air hardening steel.

When it come to metallurgy, even the slightest of difference in temperature or alloy does make some different. Then I'm sure there is a difference between -20F plate and room temp plate but noticeability is subjective thought. And I don't do plate quench, I use digital control temp molten nitrate salt for quenching alloy by the way.
 
Mildsteel (almost iron) is plenty fast for cooling 3V when dT (temperature differences in q / A = k dT / s) is above 500C. Once blade is around 500C, use Al or oil to quench, higher 'k' compensate for lower dT. This way, cooling doesn't stall before Ms... unless you want it so.

If seeking for uber cooling speed, try super quench - I do. It would be quite fun to SQ this big blade aust at 2000F, you might even get a 2 for 1 :p
 
shqxk said:
You say people use plate quench just only to speed up the process and minimal the warpage didn't you?

But actually there are also the reason of faster quench will give better steel structure even for air hardening steel.

When it come to metallurgy, even the slightest of difference in temperature or alloy does make some different. Then I'm sure there is a difference between -20F plate and room temp plate but noticeability is subjective thought. And I don't do plate quench, I use digital control temp molten nitrate salt for quenching alloy by the way.
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thermal load and conductivity are 2 different things AL plates can only conduct so much heat so fast the goal is getting 2000f steel under 1000f as fast as you can withought cracking it. the extra 80f colder plates still dont conduct all that "extra" cold to the blade heat transfer is based on surface area contact. heat travels at a set speed though the quench plates no matter what the of them is. the only + to frozen plates woudl be that they take longer over all to reach 400f and then you have auto temper issues
 
butcher_block said:
thermal load and conductivity are 2 different things AL plates can only conduct so much heat so fast the goal is getting 2000f steel under 1000f as fast as you can withought cracking it. the extra 80f colder plates still dont conduct all that "extra" cold to the blade heat transfer is based on surface area contact. heat travels at a set speed though the quench plates no matter what the of them is. the only + to frozen plates woudl be that they take longer over all to reach 400f and then you have auto temper issues
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Thermal conductivity of metal does vary depending on temperature.



Would you care to explain about the auto tempering issue by using frozen plate?
I use 500F molten salt to quench my D2/3V blade with 2 minute soak/equalize at minimum and I don't have any auto tempered martensite/bainite issue... from my experience majority of austenite just even didn't completely converted to martensite at the time.
 
i need more info on that graph why is that a c and an s group and why do some cross over each other. the fact that we are talkig about pullig heat out of one piece os steel into another thing (be it AL CP or what evern and the makers varible od how much mass they have )
the auto temper issue is pushed off by frozen plates as they have more thermal loading possable before it sets in 2000f 1x10x.100 has a far different thermal load then a bar with 2000f 1x10x.5
 
your graph runs to 600c and notice how its pointing to a common point none of it has anything to do with as quenched temps. i am guessigng we also have a quenchant thickness on the left and most guys us plates at least 1 inch thick
.650 cm that is on the graph is close to .255 inch of plate
i stick to my heat can only travel so fast out of one thing and into a nother there is a bottle neck depending on what th4e4 thing to be quenched and wht is sucking tht heat out realistically yu can not bend science is steel can only dissipate heat at a set rate and copper c only soak it in at a set rate the temperature change is a mute point
 
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