"batch" heat treating questions...

[ARCustomKnives]

Hey guys,
I had a couple questions regarding heat treating in batches, i.e., heating and quenching several blades at once... I'm not sure if this belongs in the heat treating forum, since I am technically a newbie here...

Say I have (5) 1095 blades that I want to do at once (successively).
I have typically been doing one at a time by bringing it up to temp in my oven (around 1475 deg. F) and quenching it in pre-heating veg. oil (between 120 and 150 deg. F).

My question is, can I quench all blades in the same jar of oil? Or will it heat up too much after the first blade or two? Should I have different quenching oil holders?

Also, about how long can I use the same oil for quenching blades? Does it go "bad" after a while? Or is it fine as long as I filter the scale and debris out of it?

Is there anything else I need to know when doing more than one blade at a time? Thanks...

[NJStricker]

I've done up to 3 blades at a time, but that's only because that's about the limit that my toaster oven, which I use for tempering, will hold.

The amount of heat your oil can absorb is partly a matter of volume. Each quench is going to add heat. If you use a high volume of oil (a couple of gallons) then that mass should be able to absorb more heat. I've been using peanut oil for quenching 1080, and keep a meat thermometer in the oil to monitor the temperature to make sure it stays about where I want it.

[Geno]

Air hardening steel can be done in batches.
I do folders in this manner, but mostly I make damascus blades.

My problem when heating several blades in my oven is the temp goes way down each time I open that door to get a blade out, and I have to re soak at upper critical temps before I get another. This takes time...

I find it easier to work 2 at a time in my forge. One is heating while the other is soaking.
Quench one, heat one, the next one is almost ready.

Unless you can quench them at once, why heat them up so many times?
If you CAN quench them all at once, teach us how.
Each blade must cool at a specific rate to harden, if the batch cools to slow, the whole batch is soft, too fast and they might all crack, warp,.....be harder to fix than to cook right.

Heat treating is worth ALL the time it takes, as this is where the life is put in.
Hope this helps, God bless.
Geno