Will my HT work???

S

SGTcarbine

Joined
Sep 17, 2008
Messages
28
Hello, I'm a new hobbist with a few heat treating questions. I made a small knife out of 1095 which i know is not ideal for DIY heat treating, but I want to try anyway. I have a Sugar Creek heat treating oven with no PID, if I get it up to 1475-1500 degree range, then place the blade in for 20-25 minutes then quickly quench. Will this give me a usable hardness to begain testing my blades. Also since my ht oven does not maintain exact temp, how low and high of a range can I be in with 1095 and still get a usable hardness.
 
Non magnetic is not hot enough. The curie point for steel is 1417 which is below fully austenitic for 1095, in fact it's below fully austenitic for almost all steels except for the eutectoid steel, 1084. Hyper and hypo eutectoid steels need a higher temperature, usually between 50 and 100 degrees more.
 
A couple of things I would suggest. I'd say your 1475-1500 will be alright in an oven. I would do closer to a 5-10 minute soak. Keep in mind that non-magnetic (curie point) is 1414F. If you *just* go to non-magnetic without any further soak in heat, you won't see full austenite formation. Remember that the (simplistic) goal of hardening is to create a fully austenitic blade and then quench it fast enough so as to avoid forming pearlite and rather form a fully martensitic blade. So I'd definitely go above non-magnetic (to your mentioned 1475-1500). It's possible that the success seen in water quenching, especially with an uncontrolled drop quench, may be due to not fully converting the blade to austenite.

As for quenching, BTK is correct that you can quench in water. But, expect a higher failure rate in a properly heated blade, especially with a more thinly ground blade. A better choice would be a brine solution (do a search to find the appropriate salt:water mix). It's a little less severe on the knife, but not by much. As for 1095 not liking oil, I'd say that depends entirely on the oil. A fast formulated oil like Park's 50 works extremely well. Most home brew oils...not so much. That being said, with the thin cross section in a knife, it is very likely that you can get full conversion at the edge and well up into the blade with something like canola heated to 130F. It's not ideal, but it may work.


edited to add: I type too slow. :)

--nathan
 
silver_pilate said:
edited to add: I type too slow. :)

--nathan
Click to expand...

Nathan that's OK I read really slow too.

back to the OP

If you can get some of McMaster Carr fast quench oil, it is an 11-14 second oil, it will work well on 1095. Parks works the best for me though. Like Nathan said, your set-up will work, just watch the temps carefully. Good luck
 
Thanks Nathan and Chuck, the only question I have left is, if I get my ht oven up to temp then place the blade in how many minutes till the blade reaches that temp. Is there a way to calculate this, and then add the soak time to the time it takes to reach oven temp?
 
Get the oven to the target temp and let it stabilize there for about ten minutes.
Open the door and quickly, but safely, and place the blade in. It is best to use a small rack made from a fire brick to hold the blade edge up.
Close the door and watch the temp gauge. It will drop a bit, and then start rising. When it hits the target temp again, usually about five minutes or less, start the timer. Soak for 5-10 more minutes and then remove and quench. Longer soaks are problematic without good temp control.

Quench in an 8-10% Brine solution, or roughly a cup of rock salt to a gallon of water.
As said, fast oil is far gentler on the 1095 blade and will not crack as many as water/brine.

Seriously consider adding a PID controller to your oven. It will cost $50-75 to convert it. No need to modify the current oven, just make the PID in a box with it controlling a socket that matches your oven's cord. The PID sticky has all the info you will need.
 
Thanks Stacy, I think I'm squared away now, thank you every one for the answers, and I will definitly be looking into setting up a PID controller.
 
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