Relative quench speed of mineral oil.

[Any Cal.]

Hello. I tried my last knife of 1080 in 130degree ATF. While it got hard, I am thinking it could be better. I think I know that 1080 requires a fast quench.
I checked Ellis' site for Parks 50, but it is nearly 50 bucks to buy a gallon and have it shipped USPS to me.

That being the case, I called the local feed store, and can get mineral oil for 15 dollars a gallon. This leads me to wonder what kind of results I could get with it. Would it work for the 1080? Would it work better than ATF? I would prefer to get the quench oil, but along w/ a few other tools, is more than I want to spend right now.

My last knife held an edge well, but when I dropped it onto concrete from about 40", the tip rolled a hair less than 1/16". My assumption was that meant it could stand to be a bit harder. If I am wrong, let me know. Thanks.

 

[Alarion]

Did you temper the knife, and how?
Answer could be in tempering.
It's the temper that does or unmakes the knife. Hardening is pretty simple, as long as you get to critical and quench it quickly enough.
ATF or hydraulic oil is quick enough that an untempered 1080 blade dropped on concrete should shatter like glass, not roll.
Either you tempered it too soft, or you missed the critical temp, or didn't let the steel soak enough heat to complete the transformation to austenite, and the steel didn't harden properly.

 

[Matthew Gregory]

...oil the oil he was using was not 'quick' enough to get temperature below the nose of the TTT curve for a hypereutectoid steel such as 1080.

Your mineral oil will probably be hit or miss Any Cal... your ATF will likely work better until you can scrounge up some Parks #50.

One mistake that I was making was allowing the steel to get too hot before quenching. I try to soak the blade at [what I'm hoping is] 1375-1400 degrees F for 10 minutes to bring it all into solution, but I recently watched in agony as my forge was ALL OVER THE PLACE in temperature when one of the Ashokan demonstrators used a thermocouple in it. So much for judging temperature by eye, for me...

 

[Martin S.]

Dang that's a lot for shipping! I bought a gallon of parks, propane regulator,satinite and itc refractory and the shipping was only $9.

 

[Chris Meyer]

...I recently watched in agony as my forge was ALL OVER THE PLACE in temperature when one of the Ashokan demonstrators used a thermocouple in it. So much for judging temperature by eye, for me...

Matt, I wouldn't be worried about your forge, I'm sure it was just a matter of them being to impatient to fine tune the gas and air to hold a steady temp. I have one of Tim Zowada's forges, and it's much easier to regulate at higher temps than it is at hardening temps. When I take my time and make tiny adjustments, it will hold a temp with only 1.5 degrees +/- variance. Be sure to use the air valve downstream of your blower and don't rely on that plate on the side of the blower. I would however, strongly urge you to get a thermocouple. That way there is no guessing.

 

[Plain ol Bill]

I use mineral oil for quenchant all the time with my damascus. It is made from 1080 & 15N20 so the materials are very similiar. I have had no problems at all using mineral oil and it will work well for you. Now when (and if) you get into using 1095 you will likely want a faster quenchant but till then I would stay w/ using mineral oil.
plain ol Bill
www.billsblades.com

 

[AcridSaint]

Vegetable oil has worked fine for me with 1084 and 1080, not saying mineral oil won't. Just letting you know. Every mineral oil will be different, depending on who made it, when and where. Professional quenchants will be much more accurate. Never used transmission fluid, but regular old motor oil has worked for me as well, I don't know how much slower the ATF is, but I'd stick with something thinner like the veggie oil or mineral oil in the interim.

 

[Matthew Gregory]

Matt, I wouldn't be worried about your forge, I'm sure it was just a matter of them being to impatient to fine tune the gas and air to hold a steady temp.

Thanks, Chris, but the more worked up I get myself about it, the faster I'll build a salt pot!!!


Use whatcha got, Any Cal... this stuff is supposed to be fun - but the devil is in the details, and doing stuff right is right, right?

 

[Any Cal.]

Thanks for all the replies so far.

Either you tempered it too soft, or you missed the critical temp, or didn't let the steel soak enough heat to complete the transformation to austenite, and the steel didn't harden properly.

I tempered in hot ATF, starting at 225F or so and rising to 350F I think over the course of a couple hours. I was actually thinking that the knife would most likely be too hard, and I may have to go higher on the tempering temp.

It is very possible that I did not let the steel soak long enough. My forge runs too hot right now, so I don't let it soak very long once it gets past non magnetic.

Dang that's a lot for shipping! I bought a gallon of parks, propane regulator,satinite and itc refractory and the shipping was only $9.

No, the shipping was 23 dollars I think, making the grand total 48 or so.

Use whatcha got, Any Cal... this stuff is supposed to be fun - but the devil is in the details, and doing stuff right is right, right?

The first two I made were with what I had. Now I would like to find a way to make something GOOD for my efforts. My second knife held an edge better than most I have owned, and that was with sub par equipment. Now I would like to put effort into something that can really shine performance wise. That way if I give them away or sell them, it is something good, rather than run of the mill.

Thanks for the encouragement though.

Any other thoughts on quench oil are welcome. Thanks all.