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heat treating?

W

wycowboy

Joined
Dec 15, 2006
Messages
4
Hi all I'm new here but
I was hopeing I could get some help/ advice.
I just compleated forging a fixed blade knife from an old file. I have no Idea what the steal is.
what is the best manner of heat treating/ tempering that I can do to the blade to help it hold an edge.
. thanks much J
 
Welcome to the BF. Fill out your profile so we know a bit about you and where you are.
As to the blade you made....well you already answered your question. You DON'T know what it is made of....so you DON'T know how to do the HT.
The best you can do is do a generic HT and hope for the best. Since it was an old file, lets hope it was a 10XX or similar steel. In that case ,heat it to a little above non-magnetic temp (around 1450-1500F) and try to hold it at that temp for a minute or two. Quench in warm oil ( something like a couple of quarts of ATF at 120F) and keep in the oil until cool enough to hold. Clean it off and put it in the oven at 400F for 2 hours. Take out and cool off, then put back in for 2 more hours. After this you should have a hardened and tempered blade. The next blade you make ,make it out of a known steel (1084, O-1, W1,5160, etc, ) and you will know the exact procedure for the HT.
Good luck, and let us know how it turned out.
Stacy
 
Thanks much stacy.
I know not knowing the steel is a hang up but I like working with odd matereals. I realy apricate tha advace. all I am hoping for is the best guess. and get it to hold a better edge. since I dont have a thermometer in my forge, what color will the steel be at 1500 degs. will old diesel oil work 15w-40 or is it best to use some thing thinner? I;ll be trying this soon and can let you know how it goes. thnks J
 
wycowboy said:
Thanks much stacy.
I know not knowing the steel is a hang up but I like working with odd matereals. I realy apricate tha advace. all I am hoping for is the best guess. and get it to hold a better edge. since I dont have a thermometer in my forge, what color will the steel be at 1500 degs. will old diesel oil work 15w-40 or is it best to use some thing thinner? I;ll be trying this soon and can let you know how it goes. thnks J
Click to expand...

The gauge for the critical point is when the steel goes non-magnetic. So, as it's changing to an orange color, pull it out on occation and see if a magnet is attracted to it (I do this by hanging a magnet on a string and passing the blade near it. If the magnet doesn't move, you're at non-magnetic.) Once you hit this point, plunge the blade into the quench very quickly. Don't hesitate. Also, have a lid for your quench container in case of a flash fire of the quenchant. Make sure your oil is heated to about 120-140 degrees (you can usually do this by dropping a largeish hunk of hot metal into it repeatedly until it's just a little too warm to be comfortable sticking your finger into).

Hope that helps!

-d
 
Those are some great tip. I hope I heated it enough I went to cherry colored useing my horse shoeing text book. the metalergy/ forge work section said that should be about 1500 degs for high carbon steal. I heated my quenchand by dipping in hot horse shoes,, Im a farrier by trade so they are easy to come by.. thanks j
 
One thing I've found with old files is they don't reach full potential unless you soak at critical for something between 30 and 60 seconds before the quench.

ron
 
I have stopped trying to judge temperature by color. I forge outside when it isn't raining. I see the colors differently from one day to the next, and from one time of day to a later time. A little bit of light or darkness from a passing cloud, etc. can make a huge difference in the color. Unless you forge in an area that is always lit the same, it would be hard to judge color.

When I went to a magnet to begin judging hardening temperature, I was surprised at what colors I was at. I feel that for years, I was "Way Too Hot"!

It's important to remember that you're not seeking a minimum temperature, but instead a temperature range! You don't want to be too hot or too cold. Each steel is different, so it's important to learn the steel of your choice to the best of your ability to get consistent results.
 
Judging by color is very subjective, since lighting conditions vary so much. It helps to slowly heat the steel up checking with a magnet as you go, it will gradually become non-magnetic. You will want to heat it a bit past that point and as suggested previously a brief soak at that temperature is helpful. Many file steels are very similar to if not actually 1095, W1 or even rarely W2 so a little soak will help get some of that extra carbon into solution.

One thing I like to do to zero in on the proper color I want to watch for in any given lighting situation is a trick I learned from Don Fogg. Heat a piece of the steel you are using (the blade you are working on is fine if you are doing a normalizing heat) to above non-magnetic and bring it out of the fire and place it in something very dark like a metal bucket held upside down so that you can watch the steel. In still air it will gradually darken and if you are watching closely you will suddenly see it brighten and even out again back to a previous shade where it will hang momentarily before continuing to darken. This point where it 'brightens' again is called recalescense (it happens also when the steel is being heated but is harder to see since it's in the fire, on heating this point is called decalescense) and it marks the phase transformation from pearlite to austenite on heating or austenite to pearlite on cooling. On blade cross sections it will flicker or flow across the blade due to the differing thicknesses. If you quickly pull the steel out into your current lighting conditions when you notice this brightening you will see the color you need to look for for hardening the blade (for those lighting conditions only!)
 
Guy Thomas said:
Judging by color is very subjective, since lighting conditions vary so much. It helps to slowly heat the steel up checking with a magnet as you go, it will gradually become non-magnetic. You will want to heat it a bit past that point and as suggested previously a brief soak at that temperature is helpful. Many file steels are very similar to if not actually 1095, W1 or even rarely W2 so a little soak will help get some of that extra carbon into solution.

One thing I like to do to zero in on the proper color I want to watch for in any given lighting situation is a trick I learned from Don Fogg. Heat a piece of the steel you are using (the blade you are working on is fine if you are doing a normalizing heat) to above non-magnetic and bring it out of the fire and place it in something very dark like a metal bucket held upside down so that you can watch the steel. In still air it will gradually darken and if you are watching closely you will suddenly see it brighten and even out again back to a previous shade where it will hang momentarily before continuing to darken. This point where it 'brightens' again is called recalescense (it happens also when the steel is being heated but is harder to see since it's in the fire, on heating this point is called decalescense) and it marks the phase transformation from pearlite to austenite on heating or austenite to pearlite on cooling. On blade cross sections it will flicker or flow across the blade due to the differing thicknesses. If you quickly pull the steel out into your current lighting conditions when you notice this brightening you will see the color you need to look for for hardening the blade (for those lighting conditions only!)
Click to expand...

One night I took several pictures trying to capture that phenominon. The best shot is a the top of my heat treating page here
http://www.geocities.com/son_of_bluegrass/heattreat.html
Under consistant and sufficently dark conditions I can see it as I'm heating the blade. I expect with some practice most people could as well

ron
 
cool tip for the magnet on a string deker. Never thought of tying a magnet to string, its a good idea because you will be able to tell exactly when there is no magnetisms, as apposed to holding the magnet with your hand.
 
Thanks for all your help. I heat treated 3 knives made from files withthe above method.. it seems to have worked well.. they hold an edge much better. great site J
 
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