Need some heat treat help!

J

Jscagg

Joined
Feb 4, 2019
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1
So since I started my venture into knifemaking, I've been having issues with heat treating. And by issues, I mean that none of my blades seem to heat treat right. I'm using a little homemade "forge" that is a few soft firebricks that I carved out so when put together it has a hole going through the middle large enough for any knives I make. I drilled a hole in the side to put my torch though, I use a Bernzomatic TS8000 torch that will heat everything up to a very bright red, way past non-magnetic. The metal that I use is 1095. My normal process is to let the forge heat up a bit, and then through my knife in, I check it often to make sure it doesn't get to hot. I use a magnet to test and see if I've reached non-magnetic yet, and once I have, I let it go the standard "Just a little bit more" and then quench in canola oil.

I know that overheating can be a real thing that can make your metals not harden properly, but I don't think I leave the knife in long enough for that to happen once it hits the non-magnetic point. Normally once it hits that point, I have it out and quenching within 20 seconds or so. I also keep my quench right by my forge, so its not long that the blade is out of the fire. So far in about 7 knives, I don't think I've actually successfully heat treated one. Out of the entire knifemaking process, I'm finding this step to be the hardest to get down.

Any tips on what I can be doing wrong? I don't have the money to get a temp gun and see what my temps actually are, nor can I afford even a cheap oven currently, so I'm limited to just my firebricks and torch.
 
I realized after posting this, that I put the post up on the wrong account!:D Hi guys, and thanks in advance for any tips!
 
How do you know they aren't hardening? Do you have a hardness tester or are you file testing? If file testing it may simply be decarb. Grind a bit then retest.

Also you should be heating your oil.
 
if you are going way past magnetic, you may be getting grain growth. but near the end you say you go just a little bit more than non mag,. so that is confusing. 1095 requires a holding time at a certain temp, which you cannot do in a forge like that. what temp is your oil at when quenching ? i would suggest 1084 steel, which does not require a holding time. what are the clues you see that lead you to believe you are not heat treating it correctly ?
 
Sounds like you understand the process and you're checking to make sure you're getting hot enough. The real problem is that 1095 needs a SUPER Fast Quench and canola is not fast enough especially when heated. You Need an engineered Oil Parks 50 is the Oil of choice for 1095 and you use it at room temperature. 1095 is close to water quenching steel but water will crack it sure as the sun sets in the west!!! Since you have no way of testing the actual RC Hardness I suggest you try grinding a little to get down past any possible decarb and do it in a darkened area and watch the Spark pattern Hardened Steel throws Showers of sparks.
 
Welcome Jscage.
If you fill out your profile we would know where you live and a local maker could offer to check you blade and do a HT with you in his forge or oven.

The above fellows offered good info, but before you go and change anything, check and see if there isn't hard steel under a soft skin of decarb. When heating a blade in a forge like yours, the surface oxidizes a lot, creating a layer of steel with the carbon "burned" out of it. You have to sand/grind that layer off the blade to get to the hardened steel. If using a file to check the edges and it seems to bite in and file a little steel when you check, file some more and see if it suddenly starts to skate off.

That said, a two brick forge is pretty minimal and doesn't do a very good job of HT.

As pointed out by Busto, 1095 isn't the best steel to try and HT in a setup like yours. You would be better to use 1084 or 5160.
 
I just want to say thank you to everyone that responded and gave me some good advice, and also to apologize for not replying sooner. Today was a busy day! In response to everyone here: While the forge is capable of getting things way past non-magnetic, I don't take anything that far. I keep a very close eye on my temps, at least as much as I can given that I don't have a temp gun or any way to see what the actual temperature of the forge/blade is, I apologize for any confusion on that part. I've read mixed HT techniques for 1095, some said to soak it, others said you don't have to, so I wasn't sure what the proper way to do it was. I was able to get my hands on some cheap 1095, so that's why I opted to go with that, over some other steels. That being said, if I'm not soaking it properly, or as Busto pointed out, my oil isn't quenching it fast enough, that could be my issue as well. I also keep my oil at room temp, as I currently don't have a way of heating it up unless I put it in a pot on the stove and heat it up that way, then transfer it to the little 'quench tank' I have, which would suck some of the heat out of it in the process. So perhaps that's another issue?

I also didn't realize that what I'm seeing, could just be a layer of decarb that I didn't know was there. The only way I can test my knives currently, is by file testing. So when I run the file along a blade and I feel/hear/see it bite in, I assumed that I just didn't HT correctly. But now, maybe I was just filing off the decarb and not knowing it? Tomorrow or the next day I plan on working on another project, and I'll see what happens with that. I can give it a post-HT grind and then test what's exposed and see what happens. From there I'll figure out of I may just need to switch to a different steel like 1084 or 5160 as suggested by Stacy E. and a few others.
 
I have a 3" long piece of 1.5" mild steel round stock welded on the end of a 24" piece of 3/4" mild steel round bar. I heat that in the forge while the forge is heating up and when it is red, I quench it in the oil tank. Push it up and down and stir all around. The tank usually comes up to around 120 that way.

I only heat the medium quench oil like this, as the Parks #50 doesn't need heating unless it is below 60 degrees. If it is cool or cold, I give it a quick heat-up with the hot prod as above, but don't get the end as hot.
 
JSCutlery92 said:
I just want to say thank you to everyone that responded and gave me some good advice, and also to apologize for not replying sooner. Today was a busy day! In response to everyone here: While the forge is capable of getting things way past non-magnetic, I don't take anything that far. I keep a very close eye on my temps, at least as much as I can given that I don't have a temp gun or any way to see what the actual temperature of the forge/blade is, I apologize for any confusion on that part. I've read mixed HT techniques for 1095, some said to soak it, others said you don't have to, so I wasn't sure what the proper way to do it was. I was able to get my hands on some cheap 1095, so that's why I opted to go with that, over some other steels. That being said, if I'm not soaking it properly, or as Busto pointed out, my oil isn't quenching it fast enough, that could be my issue as well. I also keep my oil at room temp, as I currently don't have a way of heating it up unless I put it in a pot on the stove and heat it up that way, then transfer it to the little 'quench tank' I have, which would suck some of the heat out of it in the process. So perhaps that's another issue?

I also didn't realize that what I'm seeing, could just be a layer of decarb that I didn't know was there. The only way I can test my knives currently, is by file testing. So when I run the file along a blade and I feel/hear/see it bite in, I assumed that I just didn't HT correctly. But now, maybe I was just filing off the decarb and not knowing it? Tomorrow or the next day I plan on working on another project, and I'll see what happens with that. I can give it a post-HT grind and then test what's exposed and see what happens. From there I'll figure out of I may just need to switch to a different steel like 1084 or 5160 as suggested by Stacy E. and a few others.
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The decarb is typically less than 0.010”, but in a forge, you might get 0.020”. (I know a proper blown forge can have better atmosphere control, but that’s not what is being used here.) if you can file deeper than 0.020”, it’s probably not hardened.
 
I'm pretty new to this as well but do enjoy heat treating my own blades. I dont use anything other than 1084 and have found a system that makes a good knife with simple tools I use a magnet to thermal cycle to some degree but have learned to do this in the dark and watch for decelence (not sure on spelling) with 1084 and others probably, you can see when it needs quenched. Since I started doing this, I've been 100% successful. I think it's worth learning if your using simple tools and simple steel. My knives are incredibly tough and hold an edge better than most of my bought knives
 
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