heat treating help

Hello to the group
I have a Damascus blade I have been working on . It is finished except for heat treating and tempering. I am not sure how to handle this process with a
Damascus blade. It is made from off the rack mild steel and radial arm saw blade steel.
Thanks for any help you can give.
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Have you done knife-blade heat treating before? Which steels and what equipment? Did you do the welding?

That radial-arm saw blade is prob'ly 8670-modified or maybe 1069 or maybe something like 4140 even.
What brand was the saw blade and was it carbide tipped?

Cool, but'll need more from you first. ;)
http://www.panix.com/~alvinj/testsamples.htm
I want someone to make a knife blade from pattern welded 1069 (Oldham) and 8670-modified (Vermont-American) to see how it turns out. ;)
Alvin in AZ
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Thanks for the reply.
Ok sorry about the lack of info I will elaborate
Have you done knife-blade heat treating before?
Yes But only on several small knifes. They were all made from 5160. I use a mineral oil at slightly above room temp to quench them and tempered at about 450 f.
Did you do the welding?
Yes I welded this knife in my propane forge I used three layers of the saw blade with two layers of the off the rack mild steel. I use plain borax for flux. So far the blade has no inclusions or cold shuts.
What brand was the saw blade and was it carbide tipped?
Yes the blades are carbide tipped. They are from a 16" dewalt radial arm saw at home depot. The blades are worn out I cant make out the brand.
I am pretty low tech I use a large can of the mineral oil to quench and the oven in the kitchen to temper.
Thanks again for the help.
I have picked up a lot good info from your posts over the last couple of years
thanks james

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No sweat, just don't know where to start, let alone go. ;)

This new blade can be treated the same. :) Have you been using the "magnet method" or the "shadow (arrest point) method"?
The mild steel is going to mess with you some, since the point it goes non-magnetic is higher (too high?) than medium to high carbon steel.

Betcha it's 8670-M but if you're up to spark testing it you can be pretty close to sure. ;)
Using one of the left-over pieces, in the dark, compare the sparks thrown by a cold chisel and the left-over piece. The rather large separated arrow-heads at the ends of the stream is Mo.
Ni makes the sparks whiter too. It should be easy to tell if it's 8670-M or ~4140 (same as 8670-M but much fewer carbon bursts) or 1069. 1069 will look a whole lot like your typical cold chisel.
An Enderes cold chisel is what I use since it's a known sample-> 1078. :)
Cr (and V) suppresses the bursts, but in this case there isn't enough to see that because of all the rest of the alloying in there. With 1095 versus 50100-B the Cr&V's effect can be seen.

Low tech is best when working with relatively-unknowns like this. IMO, "going by the numbers" is for industrial production work.

Cool! :) I couldn't ask for more. :) It's my hobby. :)

Alvin in AZ
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Thanks again for the reply
I have been using the magnet method so far. I don't know another way.
I tried the spark test. About all I can say for sure is I get high carbon type sparks from it.
I have heat treated and tempered the blade. I cooked it at 400f for about two hours. I got a medium dark straw color to it. It is quite hard the file skates over it on a test.
Thanks for the tips.
james
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What happened to me is I learned about heat treating by reading metallurgy books in the late 80's. My first clue to when the steel was ready to quench came from a graph that shows how the steel's temperature actually drops back slightly and also lags (time wise).
That property can be seen after part of the steel gets through that "arrest point" and the center/thicker sections have a shadowy/darker cooler look while they are going through it and almost ready. When the whole piece smooths out to one color, it's ready to quench.
I call it the "arrest point method". :)
The "magnet method" sure as heck works, and in full sun (and other situations like that) might be the only way to go! :) Otherwise I believe the arrest point method is a more precise method "when it works;)". YMMV

Yeah it's 1069 or 8670-M then. The spark difference between those two is seen mostly at the ends of the stream. If you're going to mess with saw blades much (I claim;) it'll be worth knowing the difference by learning to spark test them, so when you weld the two together you'll know what you've got, is what you wanted? ;)

Cool, sounds like it worked. :)
Did it sharpen up nice? :)
I've had some trouble with that where the edge is "crumbly" and can't be made smooth. It happens when I re-heat treat old butcher knives. :/
My latest finished work...
http://www.panix.com/~alvinj/ggrampa.htm
That re-heat treated (and cold treated:) spear blade sharpens up real nice! :) The other two blades are O1 and it always sharpens up nice.
Alvin in AZ
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Thanks for all the advice.
I am really more interested in artistic functional iron work. I guess pattern welded knives would fall in that category to. But more into pot racks lighting custom trellises and the like. I haven't sharpened the blade yet I will let you know how it turns out.
Thanks again.

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Ok, in that case spark-testing isn't so important. :) Spark testing's important if you're making tools or machine parts.
No "thanks" needed! It's all "hobby talk", see what I mean? :)
Alvin in AZ
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Don't know if you ever got your answer, or if you got the blade heat treated and tempered. You basically handle the damascus as you would a regular blade. Bring it up to non-magnetic then quench in oil, I usually do this 2-3 times. Then tempering I use a toaster oven at between 350-400 degrees for an hour, let cool to room temp. then do it again. I've done this on all my blades including damascus. Hope this helps. TomNBandera
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Why do you quench 2-3 times?
Eide

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