Anneal/Soften a hidden tang on a HT Blade?

LobosStyle Blades

Well-Known Member
Hey guys...I'm making a few hidden tang 440c blades and have created a new technique. Basically I have a heat treated blade with a hidden tang that was to be attached to an all-thread. I've sized the tang down to thread it but can't do so because it's too hard and ruined my tap (stupid me tried to soften it but wasn't able to).

Question....

DOES ANYONE KNOW A WAY TO ANNEAL/SOFTEN A TANG WITHOUT RUINING THE HEAT TREAT ON THE REST OF THE BLADE?


I'll post photos of what I'm doing once I have a chance and am not at work.
 
For the scenario you describe, I'd just hold the blades in a gloved hand and heat the just the end of the tang where the threads will be with a torch until they're past the 'blue' color range and into the 'gray/silver' range but not up to 'red' yet. Then I'd let them cool. Shine the tang ends up so you can see the colors come on again and repeat two or three times. Should be good to go at that point. I don't work with stainless, but with taking them up to red and letting them air cool, you may still get some hardening?

If they were carbon steel, I'd do the same thing and take them right to red and let them cool. Then again, with carbon steel, I wouldn't have hardened them in the first place. :D
 
Off topic, but John you need to get your JS stamp, I just can't reconcile your work and advice followed by the word "apprentice".
 
For the scenario you describe, I'd just hold the blades in a gloved hand and heat the just the end of the tang where the threads will be with a torch until they're past the 'blue' color range and into the 'gray/silver' range but not up to 'red' yet. Then I'd let them cool. Shine the tang ends up so you can see the colors come on again and repeat two or three times. Should be good to go at that point. I don't work with stainless, but with taking them up to red and letting them air cool, you may still get some hardening?

If they were carbon steel, I'd do the same thing and take them right to red and let them cool. Then again, with carbon steel, I wouldn't have hardened them in the first place. :D

Thanks John. I did the red hot with a torch and tried to let it cool slowly but it seemed to harden. I know a lot of people will air harden stainless so I figured that was what I was getting. I really appreciate your input on this. I'll try it again and see if I can get it to work. The color helps and I really don't want to have this HT ruined. My first attempt I Put a wet cloth around the area I wanted protected and that did a great job on keeping the HT for the blade.
 
Was it me, I would just add a piece of all stainless thread to the tang with a lap joint, pinned and brazed. Much simpler under the circumstances.
 
John, your process worked great and was not time consuming at all since I was grinding on another blade. I can't thank you enough. I went through 6 cycles just for good measure but was able to thread the metal without any issue as all.

The idea here is to maintain a lighter glade but still a strong handle. By putting a pommel piece on it will maintain the pressure on the handle. A welder friend of mine says that you can't weld 440c as it just won't work so this was the next best I could come up with and verify it is a strong connection. I'll do a JB weld on the inside and smooth out the sides to make the connection smaller. Inside the handle material, I fill it with an epoxy anyways, prior to inserting the bolt.

The process is simple and there are no concerns as to a solder or glue/resin coming apart down the road as it is a mechanical connection. This is for a carving set so it won't get heavy field use, but looking back on it, the hole there that is put in at the request of the heat treater will be put further back in the future and ground off as to not weaken the tang.

Any experts out there have any thoughts? Suggestions are always welcome.



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Those perfectly square cuts right where the tang and blade meet are just as weak as the hole in the tang for the heat treater. A smooth radius would be much stronger.

is there any reason you couldn't thread the tang before heat treat, then just clean it up a bit after? 440C is pretty dimensionally stable, certainly enough for the coarseness of the threads you're cutting...

Thanks for the input. I had this set water jet cut prior to sending it for heat treat. I didn't come up with the threading system until after I got the pieces back from HT. It came about when I was not happy with how my original set up was done so I was looking for something more secure. The idea came one night about 3am when I couldn't sleep. For future pieces I'll definitely do threading prior. I even had a set of CPM-3v I thread pre-HT and they came back awesome.
 
Hi. About your question. You can anneal the TANG WITHOUT RUINING THE HEAT TREAT ON THE REST OF THE BLADE by sticking the blade in the plastic bottle with cutoff the upper part of the bottle and filled with the wet sand and use your gas torch to anneal the tang. The blade will be in soacked wet sand, so you don't have to warry about it.
 
I have a similar situation going on right now. I have a full tang blade made out of d-2 and was trying to soften up the handle area in order to drill some more holes. I wrapped the blade portion with a wet rag and heated the rest up red hot. It's 1/8-3/16 thick and took awhile to get the temp that high. My forge isn't real good yet so I could only do about an inch at a time and I started near the bolster area, then the butt, then the center. Then, I let it cool slowly in the forge. I ended up with workable steel handle area:biggrin: but also with some light straw oxidation in the blade area as the heat began to dry up the rag. Good call, indeec_shaman on using wet sand. -Next time:35:

The thing I'm worried about is if I went too hot and ruined the strength of the knife by doing it this way.:sad: It seems like this method would have done something to the steel (grain structure?) somewhere around the handle and the blade. I also didn't plan on doing anything else to the handle, but was going to leave it annealed. I should have researched more and tried to soften it at a cooler temp.

I know this is a late post to this thread, but any thoughts out there?

Thanks everybody:57:
 
Soundmind -

So I've been doing this process for a little while now and have done it with great success. I follow a modified version of what John Doyle recommended. The first thing you'll want to know is that you should be using a torch and not your forge. With a torch you can focus your heat to an area where the forge you run the risk of ruining your heat treat on the blade itself. I got my torch at Home Depot and have used both propane and mapp gas for the process. I like mapp because it gets hotter and I can complete the process quicker.

So here's my process....note that it's for 440c and not D2. One of the more knowledgeable metallurgists here may have different info for D2.

I wrap the blade in a wet rag to keep it from heating up and ruining the HT on that. Then set it in a vice to hold it while I perform the process of softening the tang. Using the torch, I heat it up past the 'blue' color range and into the 'grey/silver' and almost to the red (actually get it right to the start of the red). Then I let it cool on it's own while I work on something else for a few minutes. Once it's cool I throw it on a 3M deburring wheel that I use for other stuff and it takes all the residue away to see the raw steel again in order to see the change in colors as you repeat the process. I'll repeat the process 3-4 times depending on my mood and my gut feeling of how well the process took. Again, the process has worked well and I can do what I need without damaging the HT on the blade itself.

Here's Mr. Doyle's note on how he deals with carbon steels which is more similar to your D2. Since you're using an HT oven you don't have much of a choice in heating the tang unless you clay it during the process and don't quench.

If they were carbon steel, I'd do the same thing and take them right to red and let them cool. Then again, with carbon steel, I wouldn't have hardened them in the first place.
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Good luck and let us know how it works out for you. I'm sure others will have questions on this as well.
 
Hi Steve,

Thanks for the reply. It sounds like that was kind of what I was doing but since it was so thick (5/32) the propane was too slow. I had to use the forge to concentrate the heat - but like I said it isn't really burning that hot yet. All I'm using is a bernzomatic self lighting torch to fire it until I can get it to come together... In time...in time...

I checked out your site. Cool stuff. I'm 230 air miles from any mapp gas but its good to know about someone else doing it that way so I could give it a try later if need be.

I'll be checking back to see if anyone replies about what I might have done to the steel. This was an old conversation; I'm surprised to have gotten a response so quick. Thanks again Steve.

Oh yeah and no heat treat oven. I this was a blade I purchased from a supplier.
 
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