Did I do it right? (heat treating 1080)

W

Wyme84

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Feb 16, 2015
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Hi,
After reading lots of threads, I just heat treated for the first time, and this is what I did.

1. Using a home-made propane furnace I heated up the knife until it was no longer magnetic -- tested it on a 100lb magnet. Then I put it back in the fire for a minute to bring the temp back up. The knife didn't look red, just a little pink, but it was pretty bright out, so I am assuming I just couldn't see it.

2. I quenched in peanut oil that was warmed up to about 130 degrees. No flare up, just a little bubbling. I moved it around a little, and let it cool off some more.

3. Took it out of the oil, wiped off some of the scale. Then tried running a file over the spine to check for hardness -- it didn't feel much different than another piece of scrap 1080.

The whole thing was pretty easy, straight forward, and uneventful -- and I feel like I must have done something wrong?

How does it sound to you?

BTW - it is now tempering in the oven at 450 for 2 hours x2.
 
If the scrap piece of steel was not heat treated and when running a file on both you can't tell the difference then you were unsuccessful in your heat treat. You may have let it cool too much when checking with the magnet. I keep my magnet right next to my forge pull it out very quickly (actually i dont even pull it all the way out because my magnet is a telescoping type) and check and it goes right back in. Probably only takes me a second or two and then if it doesn't stick it's back in for about 30 seconds or until it visibly gets a bit brighter.

I try to do mine in a darkened area and I can always see plenty of color. If your file is skating over it without biting in your where you want to be. Now I have had it where my file bites in just for a moment to clear off some of the scale and then it skates right over it without biting. So far even with my very limited experience but talking with others I've found guys have a tendency to go to quickly to quench after nonmagnetic.

I'm sure others will be along shortly with additional advice.

Jay
 
After making sure it was non-magnetic, I did put it back in the fire for about a minute.

I didn't press very hard with the file, it felt like it was catching, but I think it may have been just the scale that was coming off.

Its already tempered, is there a way to check now? Should I re-heat treat?
 
If it's already tempered, put an edge on it and test it. Cut some paper, cardboard, and wood. If it holds an edge well and doesn't roll too much then its probably good.

That's the trouble with not having precise temperature control. You may have to test the edge and try to be objective as possible.

With 1084, I used to use a forge to ht. Heat to non magnetic. Put it in a little bit longer and watch for the colour change in the steel. Then quench in 120 degree canola oil. Temper at 400 - 425 depending in the knife. That always worked well for me.
 
Practice makes perfect - grind an edge on a roughly knife shaped scrap and heat treat that, do a quick torch temper and sharpen it up.

Although if you are like me the scrap will probably turn out like a razor and the carefully shaped knife not so much. But still - practice is good.
 
I don't think you can wipe off scale. There is the stuff that flakes off in the quench, but that's just from quenching in oil, same as the coating on a seasoned skillet. The actual scale is grey and has to be ground off just a bit to get to bare steel. After temper, grind it down a bit until it shines, and retest with the file.
 
Decarb and scale are often confused and decarb has not been mentioned. This is a layer of steel, on the surface, that has had the carbon stripped.....and that carbon forms the scale. The file will bite into decarb.....like it was mild steel.

If you haven't already, sand thru the decarb layer. If the steel did harden, you'll notice it when sanding. You'll be removing steel like it was annealed, and all of a sudden you'll feel and see the change.
 
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