How hot is non-magnetic?

[Jacktheknife]

Howdy Ya'll,

I have 26 blades to heat treat,
and a single burner forge.
I understand one heats the blades to non-magnetic,
and within a second plunge them into hot oil, {150 degrees..}
Then 400 degrees in the oven for 4 hours for tempering.

Questions :
1. Is a single burner enough heat?
2. What color am I looking for, ie.
Orange.. orange-yellow...
Or 'plumb yeller' ?
3. And won't a few hot railroad spikes thrown in the oil do for an oil warmer?
{I am using 1/16" x 1 1/2" 1095 steel.}


Help ???


J. Winters Knife

[Ray Rogers]

Well, let's see...where to start. For most carbon steels non-magnetic is approximately 1500 F. I guess that would look like dull red to dark orange to most people under most dim lighting conditions. But, that's why we say 'non-magnetic' - so you don't have to know the temperature or the color. As the steel heats up, you periodically touch a magnet to it. When the magnet is no longer attracted you are at - or beyond - non-magnetic. You don't really want to go more than about 50 degrees beyond so check often. Do NOT leave the magnet in contact with the steel while it is heating, you'll just ruin the magnet.

150 degree oil is ok, but 125 will do too. Some railroad spikes will probably get the job done, depends on how large a volume of oil you have. Don't obsess over it but do try to get the oil to the same temp each time you use it so that your results are consistant.

Yes, a one burner forge can do it but it depends on the insulation too. Use the magnet, it will tell you if you did it or not.

400 degrees in the oven is OK but 4 hours is overkill in my opinion. Instead, put them in for 1 hour, then take them out and let them cool to room temperature. Then repeat that process a second time, maybe a third time but that's enough.

1/16 is very thin and won't take long to reach non-magnetic and will easily over heat so pay attention. Try to do each one the same way, and afterwards, test a couple to destruction so that you know if your process worked or not ...

[Txcwboy]

I hang a magnet near my forge on a string. When I approach the magnet with a hot blade, if it swings I know its not hot enough yet. It it doesnt move its time to quench .

good luck

Dave

[Jacktheknife]

Thanks Ray, I wasn't sure if my 'one burner forge' would do it.
I'll harden and temper these tomorrow! Gun show coming in 6 weeks.
and txcboy I see you are up in Plano, I am south of Lancaster,
thank you too!

J. Winters Knife

{Hey Mete, thank you too !}

[mete]

Curie temperature ,at which steel becomes nonmagnetic is 1414 F.Hold at nonmagnetic for 5-10 minutes...2 hours ought to do for tempering ,or if you want 2 hours , cool to room temperature then 2 hours more .

[Jacktheknife]

Good afternoon Ya'll

Well, My 'Lisch' forge is on wheels so yesterday,
I rolled it out in the shade.
A gallon bucket of used motor oil was right by the forge.
My 26 skinners on a handy stump,
and I was going to harden my first blade ...
The 1/16" blades bypassed red and turned 'spotty' orange in a flash.
The two railroad spikes intended to warm the quenching oil were not even warm.
The color of the blades went from spotty-black-orange to orange,
I figured it was all hot.
so I checked the magnetisity and there was none.
First non-magnetic steel I had ever seen, but...
I had no idea how far past non-magnetic it had gone,
and I was told 50 degrees was about enough so I stopped the forge and let everything cool.
My friend from Oregon said:
"Don't quench if the temp. is dropping either, only rising."
I came back in and let all the information I had amassed subconsciously order itself in my brain.
And drank up all my wine.

So Today ...

Pull the forge back into the shop where it is kinda dark.
There is clock in the shop which will help.
And my clipboard to keep notes.
First heat the oil with some hot spikes.
Then ... one at a time,
put a blade in the forge and watch it.
Ray, you were not kidding when you said 1/16" HEATS FAST !
I was in this wreck and my timing is bad
but I think the blades were heating at the rate of 500 degrees a minute.
So today I will have the clock to help.
But I also intend on checking for non-magnetic... constantly.
One magnet on my iron rod
and another on a string hanging off the forge on the way to the quenching oil.

I imagine like everything else in life it is easy if you know how.


J. Winters Knife
Published Poet
and Killer of Whitemen

[mete]

If you get it too hot you'll be in a spot , for at 2600 Fahrenheit the magnet again will hold tight !!

[Ray Rogers]

One thing you might consider with those very thin blades is to make a bundle out of 5 or 6 of them. Wrap them tight with baliing wire and then treat them as one blade, quenching them all in one shot. Helps them heat up and cool down a bit slower. This will cause the blades in the middle to cool slower than the ones on the outside so they may be a little bit softer. The ones on the outside, cooling faster on one side than the other, may warp just a bit but straightening thin blades later during the tempering phase is usually pretty easy. Anyway, it's something to try.

Definitely heat the oil up before you start heating the blades. The oil may require several cycles with the spike before it gets warm enough and it won't cool down very quickly....

[rhrocker]

Originally Posted by mete

If you get it too hot you'll be in a spot , for at 2600 Fahrenheit the magnet again will hold tight !!

I didn't know that! I just continue to learn something about making knives every day!

[mete]

For those who don't know , at about 2600 F there is another crystal change to delta ferrite which is magnetic.

[Jacktheknife]

Afternoon Ya'll,

Today is 17th of May, and I have sucessfully heat treated 7 blades, washed them up,
and am waiting on the oven to reach 400 degrees and I will throw them in and temper.
My single burner 'Lisch' forge heats 1/16" steel, to non-magnetic in under a minute !
I got a chair and set it in front of the forge the better to watch the blades.
Good idea it was too, I was more steady and had a better view in the forge.
Could work faster as I was closer to the forge and the quenching 'can'.
When I was sure they were a little past non-magnetic I quenched in used motor oil with 20% transmission fluid in it. I am more confident and can do the others tomorrow.
{A friend is coming by and we are going out to the lake.}
Now as the oven heats up I am thinking about finishes for the blades.
May make that Gun Show after all,

Thanks all of ya'll,
for not only helping me get past the heat treating Illiad but also just to have a forum to tell this stuff to.
I don't know many other knifemakers.


J. Winters Knife
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