tips heat treating 1/16 inch thick steel

M

Matisw

Joined
Oct 17, 2018
Messages
21
I am making a bread knife, started out with an 1/16 inch thick 1080
  1. Would quenching it cause it is to bend/buckle, etc?
  2. Does it need to be heat treated at all? I would like to do it, it is my first knife and want to learn by doing.
  3. If I do heat treat it, should I not quench it?
  4. Should I heat it up to non-magnetic and then let it air cool and then stabilize in my oven at 400 degrees, etc?
thanks.
 
1) Yes - warp on thin blades is normal and to be expected.
2) YES!!! - It will be useless unhardened.
3) NO!!! - you always need to quench 1080
4) NO - see above

HT for 1080:
Heat to 1485F-1500F and quench in a faster oil. Canola will work. Use at least a gallon, two is better. 1485F-1500F is about a shade lighter in red than when the magnet stops sticking.

HT the bar unshaped and then shape and finish it hard. The only thing to do before HT is drill the holes in the tang and maybe round the nose. You will need a belt grinder to do the shaping after HT.
Use quench plates to take care of warp and twist when you pull it from the quench oil. While the plates are normally 1" or thicker alun=minum, even wooden boards would be better than nothing.
 
first of all, thanks so much for responding to my questions, we all have to start somewhere, the only stupid question is the question you know the answer to.

  1. That being said, unshaped you mean to say without the grind, or are you saying that I should not shape it all, and heat treat the bar/billet before cutting the shape of the knife?
  2. I have already shaped the knife! Can I salvage it?
  3. RE: Quench plates, can you give me the basic tutorial on how to do it? I may just use 2 x 4's for starters
 
Matisw said:
first of all, thanks so much for responding to my questions, we all have to start somewhere, the only stupid question is the question you know the answer to.

  1. That being said, unshaped you mean to say without the grind, or are you saying that I should not shape it all, and heat treat the bar/billet before cutting the shape of the knife?
  2. I have already shaped the knife! Can I salvage it?
  3. RE: Quench plates, can you give me the basic tutorial on how to do it? I may just use 2 x 4's for starters
Click to expand...
1: I don't want to speak/interpret for Stacy here, but I'd grind the blade's profile and drill the holes but don't grind the bevels of the blade.
2: Yes. It may be more prone to warping, though... especially with uneven grinding.
3: The idea here is to quench the blade in oil following Stacy's advice above but then take the blade out of the oil quench while it's still hot and malleable (less than ~900F degrees but more than ~500F) and clamp it between the two flat plates to prevent warping while it cools down and finishes the conversion to the hard martensite.

I'd highly suggest taking some time to read through the stickies in the Shop Talk, especially those relating to heat treating. Also, spend some time on Larrin's KnifeSteelNerds.com website. The information in both these resources is invaluable and a great way to begin the learning process. Taking the time to do this before asking questions that may very well be answered there already is good forum etiquette in my esteem. Good luck on the bread knife!
 
thanks, I appreciate your advice, especially on the quench plates. And thanks for the tip on KnifeSteelNerds.com, didn't know about
 
I agree with Destructabot's post.
It is better to harden such a thin bar as a plain bar, but profiling the bade won't cause and damage. It may tend to warp a bit worse, but that is what the quench plates take care of.
 
ok, btw, all I have is an angle grinder, hacksaw, dremel, and files, I am amazed at what I can accomplish with the files, btw...
 
I used to have hell w/my L6 saw blade material until I realized that the warping was at least as much caused by "how" I heated up the blade as "how" I quenched it. Hot steel looks hot yes? but steel is a poor conductor of heat so even though it's cherry red, it's not necessarily heated evenly. So when I'm heating up .70/1000 material to quench, I make sure I match pass for pass, the torch heat up on both sides. I've not had any warp in some time now and what has, has been minimal.

This sort of stuff:
(click the pic for an enlarged vue and, for those not on/members of flickr, (Yahoo) tell me "if" you can do that please or does it deny access?)

IMG_20181014_140630_293 by rynegold, on Flickr

20181014_135648 by rynegold, on Flickr
 
Got it, so in layman's terms, if the metal is heated unevenly, then it can warp.

That makes (in my non-metallurgic-trained mind) sense because if the metal is at different temperatures before quenching, then it cools unevenly, and therefore constricts unevenly, causing warping.

Maybe I just spoke out of my rear end, but it sounds plausible!
 
That is more or less right.
What happens in the quench that causes warp is not exactly uneven cooling but that the structure changes from austenite to martensite unevenly. Martensite expands as it the carbon atoms rearrange. This makes a katana curve up and form the sori ... and makes a thin blade warp.

Part of the reason for a soak time in HT is to get all the alloying and carbon where you want them, and part is making sure the steel is evenly heated through and through. This is one reason warp is more of a problem with a torch ( hard to not get warp) or a small one brick type forge. A HT oven or larger forge will evenly heat the blade. Quench plates will eliminate warp quite well.
 
I see people online only heat treating the blade and not the handle, wouldn't that tend to cause more warping?
 
You must log in or register to reply here.
Back
Top