Quenching question?

flatgrinder

flatgrinder

Joined
Dec 20, 2005
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How many gallons would you use to quench a large bowie knife? 5160 steel, 5/16" thick, 10" blade.

I did an edge quench this evening using a cake pan (approx. a little over 1 gallon) filled with auto transmission fluid and it burst into flames!! :eek: Threw some kaowool on it and smothered the flames, but as soon as I removed it ... it lit up again. To top it all off, I don't believe the blade was properly hardened! I can scratch it with a file. I'm going to give it another try.

Maybe I should dunk the whole thing and do a soft back draw instead of an edge quench.

Just wondering how much quenchant is recommended for how many pounds of steel? Is there a general formula? If there is, I'd like to weld up a custom steel vertical quench tank with a cage (so I can move the blade up and down while it's cooling) and a lid (in case of fires). Any info or recommendations would be really appreciated! :thumbup:
 
flatgrinder said:
Maybe I should dunk the whole thing and do a soft back draw instead of an edge quench.
Click to expand...

I think it's much safer, and you're likely to end up with a better blade. I quench tip down into a tube filled with five gallons of Heatbath's quenching oil. As soon as the blade goes under the surface, any flames are immediately extinquished.
 
I would have to agree with Chris. My tank holds nine gallons. I quench point down, and never have serious issues with flame ups.
 
5160 is a deep hardening steel. It is not suited to an edge quench. Steels like 1095, W-1, etc. are better for an edge quench. I personally do not like edge quenching. You really have no control over the most important step in making a knife without a full quench. If you want a differential between the edge and spine either do a draw temper with a torch or clay coat the blade (not the best with 5160).
Stacy
 
Another thought might be to try a different quenchant. I've noticed ATF flares up something awful. Once saw flames literally shoot to the celiing from a vertical quench tank on a long Euro blade. Stinks to high heaven too.

Peanut or canola is a very good quenchant and with much less flaring as compared in either pan or tube. Also economical if you don't want to shell for the Parks 50 just yet.
 
The 5160 edge quenches just fine but may not show a very pronounced quench line. I trust you are using a temperature probe to monitor quenchant temperature before quenching. Expect a maximum 5160 hardness of about 58 HRc after properly tempering twice.

rlinger
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Sorry to be a dumba$$ but when you're all talking edge quench do you mean putting it in edge first or do you mean putting only the edge in the oil?

And,

Do the purpose made quenching oils (such as parkes #50), quote a specific heat capacity of the oils? (such that a similar "equivalent" can be found)

Lang
 
Edge only. A shallow pan of sorts. To be able to control the height(width) of hardened
area, you can put some kind of support into the pan - say pieces of steel. Adjust till you
can rest the edge of the blade on these and oil covers what you want.

You prolly still want to submerge the whole blade at some point, as otherwise the spine will be too darn soft. Say quench the edge first for 3 secs, then submerge the whole blade.

More art than science. This is why most folx resort to hardening the whole blade and then selectively annealing areas like spine. A small OA or MAPP torch. Again, you can fashion a gizmo to hold the blade where the edge is submerged into bath of water so you can paint the spine with the flame w/o risking annealing the edge. Use metal container to hold the water :)
 
langchop said:
Sorry to be a dumba$$ but when you're all talking edge quench do you mean putting it in edge first or do you mean putting only the edge in the oil?

And,

Do the purpose made quenching oils (such as parkes #50), quote a specific heat capacity of the oils? (such that a similar "equivalent" can be found)

Lang
Click to expand...

There are NO "equivalents" to proper quench oil.
I read on an earleir thread where a fellow wanted to make a new quench tank, but only had one gallon of quench, so he we refusing dimensions of tanks that would hold more than he had??!!?? Duh?
Eventually that stuff he had was going to minimize by loss, drag-out, etc. and he was going to need to buy some more anyway!
Build/acquire the largest tank you can afford to fill! If you are going to be making a even a few knives, don't you want them to be all they can be?
I had two tanks made, 8 X 8 X 30. Hold 5 gallons each. (With a LID!!!!!)
When you go to dipping in a vertical tank point first, sure you have no flame. But as that blade heats the oil on the way in, by the time you get 1/2 way in or near the end of the working portion of the blade, that oil at the top of the tube is SCREEEEEEEAAAAMING HOT! Not anywhere near the same temp as the oil that quenched the tip.
I did repeated hardness testing and the blades consistantly lost hardness from the tip to the choil area as a result of this.
Use a long tank with enough capacity to quench two or three blades without changing the mass heat of the oil more than about 10 degrees.
Place the entire blade in edge down all in one dunk! Then the entire edge was quenched in the same temp oil all at the same time.
The hardness remains the same from tip to handle.
Get the right oil, get a decent tank.
 
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