(HT?) not sure about this 1084 after quenching?

MarkJeffrey

MarkJeffrey

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Nov 7, 2013
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So everything I have done so far has been with O1, and I do HT in my shop with an evenheat kiln, but I'll be the first to admit that even though I do have that I still have a pile of stuff to learn. All of the O1 I've done so far seems to have come out fine. I usually check by run a file over some of the edges.. but I did 5 blades in 1084 today and I wasnt so sure about the file test after I quenched them. It didnt seem to skate off quite like the O1 does. So I did it again.. seems ok, but still not quite? I soaked at 1500* for 8 minutes and quenched in 130* Canola, I did some reading on HT for 1084 and it was all a bit different it seemed but right up that alley.

One thing I did do differently (and I thought this would be for the better) was I quenched all 5 blades at the same time. I loaded them in the kiln with a piece of O1 square bar through the lanyard holes, each blade was roughly an inch apart from each other. The reason I did this was to keep the oil from getting to hot by the time I got to the last blade,. and for that last blade not to loose temp by the time I got to it.
 
Mark, depending on size of the 5 blades you did at once, perhaps it heated the oil enough it slowed the oil enough to prevent full quench?
 
Not an expert at all, but I thought you were supposed to bake at 400 twice after quenching in oil.
 
Your numbers look good to me. I austentize at 1500 then quench in 130 degree canola. No need to soak it at temperature.

Only quench one at a time though and agitate the heck out of it. I use a gallon and a half of canola, and after one blade the oil usually gets too hot. I usually have to chill the oil to get back down to 130 again.
 
Think about what is happening between each blade. The 1500F blades are heating 1" of 130F oil from both sides. That will rapidly overheat the oil far beyond the range it works best at. Thusly, the oil between the blades does almost no cooling.

One blade has 130F oil all the way to the tank side to do the cooling.



All this is part of why a quench tank has to be wide enough and deep enough to hold a sufficient volume of oil to do the job. One gallon in a 4" X 8" container is just barely enough for a small blade. A 6" wide container that is at least 4" deeper than the largest blade you want to quench will be best.

A 6" X 24" quench tank with a fitted cover will do the job for most blade shops needs. Filled to within 2" of the top it holds 3 gallons.

A cut off large oxygen tank or other gas cylinder makes a great quench tank.
 
Thanks guys. Ken and Stacey, that makes perfect sense (now haha) I didnt think of it that way at the time. I was more caught up in doing all 5 blades in one heat.

I have a fairly large steel pale that the oil is in, not sure the exact size but I'd assume about 3-4 gallons.

Rancho, yes thats right but I havnt gotten to that point yet, if the steel isnt fully hardened after the quench then no sense in doing the temper cycles til I get it right.

So.. on that note, how do I go about getting all 5 blades quenched? Heat one at a time? Or, how do I cool the oil back to 130 after quenching the first blade.. and am I ok to leave the blades in the HT oven or will it drop temp too much, or just keep turning it back on? Sorry for all the questions., but.. here's one more, Will quenching the blades for the 3rd time have any negative affect on the steel? Thanks again guys, Much appreciated!
 
You can heat treat them again. Might just have more surface decarb to remove.

I have a metal container full of water that I keep in the deep freeze. I dunk that in the oil and move it around until the oil temp drops back down to 130.
 
Just pull one blade at a time and quench. By the time you have quenched and checked a blade, the oven would have rebounded enough. A little drop won't hurt anyway as long as the steel has soaked the needed time beforehand.
 
MarkJeffrey said:
So.. on that note, how do I go about getting all 5 blades quenched? Heat one at a time? Or, how do I cool the oil back to 130 after quenching the first blade.. and am I ok to leave the blades in the HT oven or will it drop temp too much, or just keep turning it back on? Sorry for all the questions., but.. here's one more, Will quenching the blades for the 3rd time have any negative affect on the steel? Thanks again guys, Much appreciated!
Click to expand...

I have experimented with several oil chilling setups. What I do now is pretty low-tech. I have a steel oil tank that sits in a rubbermaid full of cold water. A small aquarium pump circulates the water. An agitator in the oil tank circulates the oil. The circulation expedites the heat transfer from oil to water. I toggle the oil agitator on/off to manually regulate the temp.
 
I don't think the 1" in between the blades is the problem. Unless you are leaving them still in the quench, there is plenty enough circulation. What Stacy said does seem logical, but I do not think it is as much of a problem as it may appear to be. If you look how oil moves when heated, it does not circulate out from the sides. The heated oil rises rapidly, pulling new oil up from underneath. 1" spacing plus agitation is sufficient for mid-sized blades. If you were quenching cleavers or other large/wide heavy blades, I would leave more room. The longer the oil has to climb the more chance of overheating. Industry does not quench parts one at a time.

That said, if your tank is overheating after one batch quench, you need a larger tank with more oil.

on a side note...

When my tank is starting to get hot I have a few SS containers of salted ice water that I float in it. Within minutes I can drop the temp. I like the idea of a pumped circuit through a cold water container. Might have to steal that one.
 
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Mark, I keep a few large pieces of scrap steel in the freezer. When the oil temp starts to rise, I just take one of them out and circulate it in the oil. That drops the temp pretty quick. On the other note, program your oven to "hold" the final temp for five or ten minutes more than you need and (provided that you close the door after each blade is removed) it will continue to keep the temp steady as you are doing each blade. You can shut it off when the final blade is finished. That works great for me and I try to do multiple blades every time I treat.
 
Yes, industry does blades and parts in mass quantity, but they also think 3-5 gallons of oil is the amount you loose to evaporation and surface retention on each quench run.
Industry uses very different processes from pulling a blade from a small oven or forge and dunking in a can of oil.
 
Aside from the shear scale of larger facilities compared to ours, it is essentially the same operation.
 
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