tempering

2

22wmr

Joined
Mar 5, 2007
Messages
24
how do I temper steel for knives? Can I just get it glowing red in the fire and quench it in oil,or water?
 
Getting it "red" and quenching in oil/water is called quenching steel and it causes the steel to become hard. Tempering is when after the steel has been quenched you then re-heat the steel to 300-400 degrees for an hour or 2 in order to soften(temper) the steel to a useable hardness..:cool:
 
This may or may not work for the steel that you are using, heat the metal untill it won't stick to a magnet. then quench it in warm oil (130 degrees +/-). Clean the oil off and lightly sand the steel untill it is shiny, then lay the blade on the coals (cover the coals with 1/2" of ashes) with the edge up..You dont wan't to get the edge too hot.. Wait for the edge to turn a light gold/straw color.. That is a down & dirty method that may work for you...BTW what is the blade made of ?????????? (that is important info)
 
The first step ,before you touch the steel , is to read all the tutorials on heat treating you can find. The term 'temper' is only part of the whole 'heat treating' process.
 
If you verify the accuracy one can temper quite well in a kitchen oven. Doing it in a fire is a very touchy proposition, one way to make it easier is to heat a large bar of steel in the fire and then hold the spine of the blade against it until the colors bleed to what you want.
 
22wmr said:
how do I temper steel for knives? Can I just get it glowing red in the fire and quench it in oil,or water?
Click to expand...

It would be good to know what kind of steel you are working with. If you was using something like 1095, 1084,52100 you would need to heat treat in a Heat Treat Oven, If you are doing in fire you still need to know how hot it is. Most of the steel you will be needing is some like what stated above. That kind of steel needs to go up to about 1500 degrees. You will need to then quench it in warm oil about 125 to 135. You will also need to temper the blade as well. And that will be about 350 degrees for about 2 hours. You should get all the books on knife making as well. This will help you in starting out. If you need more help there are great knife makers in here who can help you out. God bless and I hope this of help to you. Please visit my Website. I have all kinds of information on there to help you out.
 
There are several factors involved:

1) Carbon
2) Other alloy elements
3) Section

Carbon must be at least .40 % for the steel to harden
Other alloy elements can dictate extremely strict heat treating parameters, making the steel impossible to properly heat treat without a computer controlled electric ht oven.
Section may dictate a harsher or milder quenching medium.
Generally speaking, the thicker the section, the harsher the medium.

Without specific, expensive equipment you may heat treat only the simplest low alloy steels: plain carbon steels.
That's not a big problem, though, because you can get excellent blades from plain carbon steel. Actually, you can play more with the heat treat and get BETTER blades from a plain old carbon steel than from some fancy steels.

All you need is a magnet.
Heat the steel slowly. Steel is a bad heat conductor, and its ability to conduct heat gets worse as it heats. Heat it slowly, and it will rise up at the proper temperature all the way through. Heat it quick and you can have a hot surface and a cold core. That's not what you want.
heat the steel slowly. Check often with the magnet: when the steel loses its magnetic properties, it's ready for quenching. This works only with low alloy carbon steels, for which the Curie point (temperature at which the steel loses its magnetic properties) coincides with austenization.
High alloy steels may deviate (and usuallly do) from this rule.
When the steel loses its magnetic properties, let it soak heat for at least 1-2 minutes more, taking care it doesn't rise further in temperature.
Then extract it from the forge and IMMEDIATELY plunge it tip down vertically in the quenching medium.
For .50 to .84 % carbon steel and knife sized stock with a 0.05" or so edge (about 1 mm) the medium should be nothing milder than 5W30 motor oil.
Hydraulic oil is better.
Quench vertically, slowly moving the blade in an "8" pattern for the first few seconds, then leave it stationary until the oil stops to move and you see no more convective motion. Take the blade out, clean away any residue oil, and grind away the scale. CAREFUL: the blade now is glass-like in hardness and very fragile!
Immediately put it on the hot gas stream coming from the forge for the temper. Heat it till the steel takes a straw yellow color. Bronze if it's a long, slim blade. No more.
Keep it at that temp for at least 15-20 minutes.
This way you'll reduce hardness in favour of toughness.
If you see the blade getting a purple color, immediately remove it from the hot gases and quench it in water or oil.
Better a violent cool down than losing completely the hardness needed for a good blade.
If you go past purple, into blue, you'll need do anneal the blade and re-harden it.
Careful: the edge and the tip will heat faster than the rest of the blade!
Let it cool slowly.
 
I admire your wanting to make your own knife!!!
IF you Start reading and learning all you can about the process and possibly get a mentor you will have a better chance!!!!
13yrs old wow, God Bless.
 
Well, that's about the age I started my first experiments at forging an arrow broadhead out of a standard screw on target point on my kitchen fire... using a hammer, and a bigger hammer as an anvil... :D
Hey, don't laugh: I managed to flatten the point a good deal before my mother came back, saw the mess me and my brother (my "blacksmith helper") had done in the kitchen and had a fit...:D :rolleyes:

I never abandoned the idea. Now I'm 35 years old, I studied metallurgy and forging techniques for more than 3 years before even just starting to experiment again, and people on this forum and others helped me a lot.
I read over 8 books about blacksmithing, too.
So, don't give up, and continue trying. All you really need is a small forge (coffee can or brick sized) and some files.
And a LOT of patience.;)
More than everything, find somebody that SHOWS you how it's done good and proper. In such things a single example is worth more than a thousand books.
 
Kevin R. Cashen said:
If you verify the accuracy one can temper quite well in a kitchen oven. Doing it in a fire is a very touchy proposition, one way to make it easier is to heat a large bar of steel in the fire and then hold the spine of the blade against it until the colors bleed to what you want.
Click to expand...
Kevin is right on the money as usual about the oven. Just mae sure you have something like an ecltronic meat thermometer with a remote probe to check the temp. The temp in the oven can often bear no resemblance to the setting, especially in older ovens with dials. The new ones with digital readouts are more accurate......MOST of the time:D
 
Have you picked up a copy of Wayne Goddard's "$50 Dollar Knife Shop?" That book is a great resource on heat treating, stock removal (using files, etc), forging, and finishing knives on the cheap.
 
well the oven is out of the question "mom says". I get how to harden it but I am still not getting the tempering part. for tempering it can I heat it up in the fire like I did when I hardened it? then do you just let it air cool? thanks for all the help guys,I under stand a lot better now.
 
Tempering can be done on the coals of a fire if you are carefull not to let the edge and point overheat..After you quench the blade, clean off the oil, rub the blade with sandpaper till the metal is shiny, Then put the blade on some coals from the fire,( rake out a bunch of coals into a pile, then spread some ashes over the coals) then place the blade with the edge up on the pile of coals (use pliers) ..Watch the blade closely as it changes colors.. you want the edge to be a gold color.. let it air cool..If the edge turns blue or purple you have to start all over again with the quenching..
 
22wmr, It won't do you any good to try this heat treating if your steel is no good. But I know what it is like to be young and excited about doing something like this..If it is ok with your parents you can send me your address and I will mail you some O1 or 1095 (both are very good knife steels) to mess arround with..Good luck with your knifemaking..Look up Tim lively online. he does tribal knifemaking using very simple tools and techniques....read this from tim lively's site also read his heat treating PROCESS it is what you are looking for http://livelyknives.com/
 
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