Heat Treat 1084 (Did I do it right)

O

Okie405

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Sep 29, 2017
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I just did my first heat treat on my first knife and I think I messed it up. I forgot to test the blade with a file after I quenched. I went right to tempering.

It is New Jersey Steel Baron 1084. I normalized by bringing to a nice even orange glow where a magnet would not stick, then I let it cool until it returned to the normal gray color. There was still some heat in the blade. I could feel the heat on the back of my hand from about a inch away but it was just a warm heat. Back into the forge it went when it reached this point. This was done three times.

For the quench I brought it to the same even orange glow where a magnet would not stick. At the same time I had another piece of steel in there getting the same temp. I used that to heat up a jar of peanut oil where it was nice and hot. Not too hot though, I could still stick my finger in it. About the time that was done the blade was just coming to the even orange glow and i quenched it in the oil. I held it in there till there was no more bubbles coming off and it had cooled significantly. When I pulled it out it was almost warm enough to hold but not quiet. I wiped as much of the black stuff off the blade as i could get off with a towel and went to tempering.

For the tempering I put it in my wifes oven at 375 for 2 hours. When it was done I pulled it out and let it cool to room temp. I then pout it back in at 425 for 2 hours. After done I pulled it out and let it sit overnight. This morning I tested with the file and found that it is leaving scratch marks. It's my understanding the file should skate across the blade and not leave scratches. Should I get all the black stuff off (there isn't that much really) and try the file again or is part of my process wrong?

PS.
If I did mess up the process can I do a second heat treat on this steel or does the knife go into the trash?
 
I sanded the black stuff off and just laid the file on the blade and dragged it across. It left scratches. I've done something wrong I just don't know what.

PS
No idea if I can try to heat treat again or if this knife is trashed but I also have another knife that I am wanting to heat treat today. My son's knife.
 
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After a 425 temper, it's likely a file will somewhat cut on a blade that was perfectly hard before temper. It's also likely that you have a layer of decarb still left, which is basically a layer of steel with the carbon burned out that doesn't get hard. Decarb isn't just the black or discoloured layer, it's also a layer under that, but the decarb depth depends on temp and time it was in the forge. The file test isn't so much about whether or not the file can make visible scratches, it's more about whether the file will actually cut into it. It's common for a file to start cutting in the decarb layer and stop once it hits the hardened steel below the surface.
 
Yes, the file is filed along the edge, not on the flat. Give it a few strokes and it usually starts sliding along.

The blade needs to be ground/sanded back to good steel. This is done on all freshly HTed blades. Don't just sand off the dark color, but sand off a few thousandths of the metal. If using a grinder, you will see all of a sudden the bright sparks start showering once yo get through the thin decarb layer. once the decarb is removed, you continue grinding/sanding the blade, to bring the bevels down to their final edge thickness. Most 1084 blades are around .030" thick at HT ( about half the thickness of a dime) and should be taken down to about .010 at the edge before sharpening. Thin slicers can go down to .005".
 
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sounds like you did ok. next time note the exact color of the blade when it turns non magnetic. then get the blade a shade brighter than that color. the correct quenching temp is a little bit above non magnetic.
 
Sorry I went and took a nap while waiting for replies. I just hand sanded till it was nice and steel. Then I went back to belt grinder and made about 4 passes, it was giving bright sparks. Ran the file across the edge and it was easily leaving marks still. Went back to the belt grinder again for 4 or 5 passes and still had bright sparks. Tested with the file again and now it is just sliding across it like it is an ice skater in an an ice rink.

I think that's it !!!!!! Right?
 
Usually you do the file test after quench but before temper, just to be sure it actually worked.

Like they said, the file might still leave marks but it should still feel and sound different. It should feel like it's skating/sliding and have more of a higher pitched zing sound as it goes across hard steel. Try it side by side on a piece of un-handed steel and feel and hear the difference. You'll feel the file bite into the soft steel more and it will make a duller sound.
 
Sorry I went and took a nap while waiting for replies. I just hand sanded till it was nice and steel. Then I went back to belt grinder and made about 4 passes, it was giving bright sparks. Ran the file across the edge and it was easily leaving marks still. Went back to the belt grinder again for 4 or 5 passes and still had bright sparks. Tested with the file again and now it is just sliding across it like it is an ice skater in an an ice rink.

I think that's it !!!!!! Right?
 
john april said:
sounds like you did ok. next time note the exact color of the blade when it turns non magnetic. then get the blade a shade brighter than that color. the correct quenching temp is a little bit above non magnetic.
Click to expand...

Also if you do this make sure you have consistent lighting or else the same temperature will look like a different color.

Since I do my HT outside I always wait until night time and always use the same light for consistency. I use pretty minimal artifical light and try to work by the light of the forge. I just enough extra light so that I don't hurt myself.
 
I have two overhead lights in my garage. One in the front of the garage where the forge is and one in the back of the garage. We turn off the light in the front were the forge is. With just the light in the back of the garage it's kinda dark in the front but just light enough to see what your doing. We found that out while normalizing, it was easier to see heat coloring while slightly dark by the forge.

We're going to do my son's knife right now. It's a chopper and long enough we will have to pull and push it through the forge for an even heat. Thats going to be a bit more challenging than my small hunting skinner. He is doing it all on his own with me only watching and instructing and i will make sure he does the next shade brighter like you guys mentioned above. Will also let you know how it turns out as well.
 
Sons knife was a success as well. Passing a longer thicker blade through is a pain in the rear. Took allot longer. We will share pics of both when we get them completed. Thanks again for all your help.
 
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