Heat Treating, The bloke method.

[gonefishin]

Again im entirely new to the craft. I have read so much on heat treating blades that it's just so hard to know which would work. I know some ways are of course better than others, but after speaking with a Bladesmith this is what I got, Will this method work...

- Forge the blade
- When blade is shaped, give it a heat until it's in a non-magnetic state then quench in motor oil
- File the blade to what you want it to look like/finish it off
- Put blade is kitchen oven on 375-400 degrees for 1 hour then let cool to room temp.
- Clean blade with soap and water
- Put back in kitchen oven for another hour on 375-400 degrees then let cool slowly to room temp.

For a rough idea, would this method be an ideal way to heat treat a knife?

[fat pete]

you should know what metal you are working with...some r oil quenching some are water...some dont matter....mild all that quenching and tempering dont do much to the metal...no carbon...the temp of the oil matters too .... i preheat mine with an old rr spike i heat up to bring the temp of the oil to about 150 then i plunge the non mag steel in it...i use transmission fluid....make sure you gotta lid handy to cover your tube...also make sure the bucket or what ever oil vessel you are using can take fire and heat...there is a story floating around about a guy that quenched in a drywall bucket and the bucket gave out....not good....i use a 4" steel tube welded to a piece of i beam so its pretty steady...untill you get used to it it is somewhat an unhandy duty...so be careful! you get some of that oil on ya it will burn....

[gonefishin]

Alright so the method above will work then, cool.
I'll make sure I use a metal bucket and stick a heated rr spike in it to get it warm.
And when you say a lid to cover my tube, you just mean a lid to cover the bucket when not in use?

[ThomasPowers]

No what he said was "it depends on the alloy"---that method won't do much for a low carbon steel; it's OK for an oil hardening steel and may result in the destruction of an air hardening steel.

The temp you quench at also depends on the alloy with some steels requiring a higher temp than non magnetic and some requiring a soak time to dissolve carbides.

The temp you draw temper to depends on how you like your edges (*real* hard, easy to sharpen, etc) and the ALLOY.

Do you see a theme developing? If you don't know what your alloy is you will want to make a couple of test pieces from it to figure out what heat treat works best for it before you hazard your good piece!

[gonefishin]

Yeah I have no idea of alloys or anything. Im completely new to this like I said, and believe me when I say I have no knowledge of it, I mean it. Haha. Im not really sure how I would go about testing or knowing how to do it all. Im looking into finding a mentor but if that doesn't work out then im not sure how I will learn. Everything I read online just says something completely different.

[fat pete]

when you quench the oil may flare and lotts of smoke so the lid is to prevent the big flames....it may sound confusing cause there are so many types of alloys, like thomas said...
you have a lot of smiths in IL.. doesnt have to be a bladesmith .... find one...there is a spark test you can use to determine approx amt of carbon of the steel but you need to practise that a whole lot till you become profficient... if you dont mind waisting some play with it and see what works best...take you time, try the different hardenning you get with your quenches..check the hardening with a file, ( it will skate over the metal and not cut)

[pkrankow]

Often two materials will behave completely different. Expect to break several pieces due to heat treat, so starting with a known stock is a good idea, you can look up published values. Do also understand that published values are for a test section of about 1 inch, and should be described in the literature. A knife will quench much faster and require a slower medium to get the same results.

Once you understand the process of heat treat, and have some successes under your belt, then start using less known or unidentified materials.

I had to do several heat treats in a classroom exercise, and every one broke the first time. It didn't matter if I did the heat treat or the lab instructor did the heat treat. Out of about 20 people, my parts were the only ones that failed like this, although other people had similar failures on one project or another. Material came from the same source, purchased new for the class.

Happily the grade was on the process and the project could be redone in cases like mine for the completion points.

Phil

[Nakedanvil - Grant Sarver]

Yeah I have no idea of alloys or anything. Im completely new to this like I said, and believe me when I say I have no knowledge of it, I mean it. Haha. Im not really sure how I would go about testing or knowing how to do it all. Im looking into finding a mentor but if that doesn't work out then im not sure how I will learn. Everything I read online just says something completely different.

Probably not "completely different" just saying the same thing in a different way.

It usually comes down to the same steps.

You must start with a heat treatable material. Nice to know what you're starting with.

Forge and/or shape the object.

Normalize. How you do this depends on the alloy.

Austenize. This is raising it to "quencing" temperature and depends on the alloy.

Quench. This can be air, oil or water depending on the alloy and the thickness.

Draw the temper. Temperature depends on alloy and intended use.

Finish. You can't usually file it after quenching and before drawing, it's usually too hard and might even break from looking at it wrong.

[ThomasPowers]

Testing:
1: learn the spark test and start building up a "sample library" to compare to an unknown piece; but realize that spark testing is just a rough guess at what you may have.

2: forge out a piece of the unknown alloy to about rough knife size, heat above non-magnetic and quench in water, then CAREFULLY with PPE try breaking it. If it breaks just in the quenching it has high enough carbon to be a knife but needs a slower quench. If it doesn't break in the quench put in a vise and then CAREFULLY with PPE tap it with a hammer. If it snaps/shatters it has high enough carbon to be a knife and may need a slower quench. If you can really wallop it with the hammer and it bends or breaks only after you get medieval all over it then it's not a good knife steel.

3: Take another piece and forge out to about rough knife size, heat above non-magnetic and quench in oil. Repeat the testing, if you fget a nice brittle fine grain fracture then oil may be a good quenchant for that alloy.

4: Take another piece and forge out to about rough knife size, heat above non-magnetic and quench in oil. Remove any burnt on oil and any decarb layer till you get to steel that will skate a new file and start on tempering tests: heat in an oven at 325 degF for 1 hour (please get an oven thermometer as the settings on the dial are almost *always* off!) , let cool and test with the file---still no bite? Re-heat 25 degF higher and try again. Repeat until you just start getting file bite. Then depending on how hard/brittle an edge you like use a temp around file-bite or just prior to it...(note if you clean the surface each time you reheat then the colour of the oxide coating will be a decent marker for what temp you like FOR THAT STEEL---this helps as you may want to do a differential temper and so have the back of the blade a different colour than the edge!)

5: now you have a good guess at a reasonable heat treat for *that* piece of steel. Remember *nothing* prevents a manufacturer from switching alloys used for a part at any time; he can just switch heat treat to make them work about the same; but can surprise you! (I have run into 1 strain hardened micro alloyed leaf spring---couldn't harden by heating and quenching!)

6: starting with a known alloy: you can look it up or follow other knifemaker's suggestions for it---and still tweak it to suit yourself better!

[Meisenmann]

- Forge the blade
- When blade is shaped, give it a heat until it's in a non-magnetic state then quench in motor oil
- File the blade to what you want it to look like/finish it off
- Put blade is kitchen oven on 375-400 degrees for 1 hour then let cool to room temp.
- Clean blade with soap and water
- Put back in kitchen oven for another hour on 375-400 degrees then let cool slowly to room temp.
For a rough idea, would this method be an ideal way to heat treat a knife?

I'd say you should re-organise your steps a little bit.

If you do it in this sequence, you are making your job harder.
You are hardening the blade before you shape it with hand tools. You should change that.

1.) Forge the blade roughly to shape

2.) normalize your blade several times. You can also go above nonmagnetic and quench the blade (use veggie oil).

3.) soft-anneal your blade if you quenched it, otherwise it will be very hard.

4.) Finish the shape of your knife with your preferred tools. Prepare the bevels and the edge (leave enough material there, from a half to one millimetre), be it a bench grinder oder files. If you are using machines, do not get the blade too hot (no colours). Finish the surface to for example 240 to 400 grit.

5.) Harden the blade. Use vegetable oil for nearly all steels.

6.) Temper the blade using your toaster oven. I temper two times, approx. 40min for each cycle. Watch the colours. You want a straw colour.

7.) Clean the blade with sandpaper and apply desired finish up to the grit you want.

8.) Make handle

9.) Sharpen knife. Avoid all procedures that develop heat or sparks like the devil avoids holy water. Otherwise you could have skipped heat treatment anyway.