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Heat Treating and Metallurgy Discussion of heat treatment and metallurgy in knife making.

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  #16  
Old 12-09-2005, 09:03 PM
mdagley mdagley is offline
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I too wondered about the .8 reading. Hmmmmmmm:confused:
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  #17  
Old 12-09-2005, 09:22 PM
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Shakudo Shakudo is offline
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come on guys .8 is 800/1000ths. and the figure is on most all electronic hardness testers and most manual testers. 44.8 RC would be a fairly soft by modern standards for a knife blade,but 44.8 is a readable number on most testers.
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  #18  
Old 12-09-2005, 09:50 PM
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Hmmm. This doesn't add up right.

It is possible a mistake was made. If they refused to do anything about it, that's one thing. But it looks like you never gave them a chance. Screaming to the world that they should never use a vendor because something went wrong without giving the vendor a chance is just not right.

They heat treat a lot of knives and have a pretty decent reputation. Life as we know it has not ended on a Rockwell tester. Please pursue this thing logically to some sort of resolution.


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  #19  
Old 12-10-2005, 11:42 AM
mdagley mdagley is offline
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My point about the .8 part of the reading is based on the only two hardness testers I've ever been around. On those it would take some 'guestimation' on the operators part to get a .8 reading. Maybe these two are different than most...................
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  #20  
Old 12-10-2005, 12:12 PM
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mete mete is offline
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The .8 is a moot point .The common procedure is to check 3 times and average the readings. I would round it off to 45 Rc. Sometimes one reading is taken to check that it's been hardened [sometimes the unhardened are mixed with the hardened !] Hardness spec should always be a range [i.e 57-59Rc ] rather than a specific hardness .Steel chemistry variations from batch to batch and even more from one maker to another will result in hardness variations....If a heat treater doesn't heat treat the part properly he has a responsibility to re do it or refund your money.
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  #21  
Old 12-10-2005, 12:35 PM
Sam Wereb Sam Wereb is offline
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With due respect to mete's expert qualified explanation,

The salient point is that Texas Knifemaker's Supply has an excellent reputation for service and hasn't been given the opportunity to re-do it or refund his money.

Bryan, your other posts show that you've been struggling with S30V for some time, just like a lot of us. Crucible may send you their recommended hardening sequence if you call them, and I think it's been posted here a number of times. I know you aren't heat-treating this yourself, but it can only help you to bone up your own knowledge.

In any case, Give TKS a call and tell us how it went. Good luck.
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  #22  
Old 12-10-2005, 12:50 PM
fitzo fitzo is offline
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This should be easy for TKS to track. S90V (420V) has an autenitizing temp and tempering temps which would mean it is not going to be included in a run with most other steels. There just aren't many steels that we use that harden at 2100-2150F. Also, assuming it was hardened correctly, the tempering would have had to be well over 1000F to get HRC that low. Surely TKS would notice if they went way over or under these temps, unless it got tossed in with stuff like S30V, ATS34, etc??

While I understand the principle of using sample tabs for monitoring a run, I personally think that a well run operation doing custom knife blades should check every single blade to make sure there weren't any mistakes.

I agree you should call them and discuss this, Bryan, if for no other reason than to help another maker avoid the same problem.

Don, I forget who (of course!), but someone else was doing the dot-triangle a long time ago, right next to their name on the ricasso.... It's a cool idea, IMHO.

All of the HT schedules for Crucible steels are available at www.crucibleservice.com
they have slipped a bit on some of the CPM's, though, in that they don't include tempering curves or charts, just a broad range. That's sort of funky on a secondary hardening steel.

Last edited by fitzo; 12-10-2005 at 01:00 PM.
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  #23  
Old 12-10-2005, 10:20 PM
Bryan McCall Bryan McCall is offline
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Ok...once again. I have not, and it was not, the intention to impune TKS. I have not "screamed to the world", as TexasJack put it, that no person should ever use TKS to harden their knives. If you like them, fine. My knife was not tested until it was complete, handle and bolsters included. My mistake. I can not send it off to TKS to have it treated again. It has mesquite handles and nickel-silver bolsters on it. If I knew how to post a picture, I would do it. Next time I will have my Dad test it before I complete the knife. He has worked in the aerospace industry for more than 38 years. He knows what he is doing. As I posted originally, he could not believe the numbers the tester was showing. There is a testing rod that is tethered to the machine at Bell Helicoptor where he currently works. It is a known hardness, 65 I think he said. He tested it. It came out right on the money. I would imagine that Bell Helicoptor has some pretty accurate equipment. More so than the average shop. I agree with your point fitzo, I will call them to let them know what happened. Maybe it can be prevented from happening to someone else. In hind-sight, maybe the title of my thread should have read: Where can I get my S90V and S30V blades heat treated properly.
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  #24  
Old 12-11-2005, 07:01 AM
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TexasJack TexasJack is offline
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You found the answer to your problem in your own post!

You have to check the metal BEFORE finishing the knife. That applies whether you did the heat treat or TxKMS or Paul Bos or whoever. It's entirely possible that the heat treater made a mistake. It's also possible you got a bad (or mislabled!) piece of steel. (As far as that's concerned, the Rock. tester might have been out of whack.) If it had been tested earlier, you could have found the culprit and at least had a chance to fix the problem.

I know you're upset about it, and anyone would be, but this is one of those great mistakes we ALL make wherein you chalk it up to "live and learn". (Trust me, I gave up trying to keep track of my mistakes years ago!!) Humans make mistakes. (The only way not to make mistakes is to not do anything.) Last weekend I attended a hammer-in where one of the most respected knifemakers I know broke a blade that he screwed up treating into pieces so we could look at the grain structure gone wrong. HE DID THAT TO LEARN FROM HIS MISTAKES.

What got all the response to your post was the accusation - whether you meant it as such or not - that the heat treater 'did you wrong'. You impuned their reputation without giving them a chance to make good. And you did it in a big public way. (The folks who read these threads are their customers!) Your approach was wrong. I know you don't like to hear that, but it's true.

Get past your frustration and use what you've learned on this project to make your future projects go better. Accept that people aren't perfect and allow yourself room for adjustment when that happens. And - please - understand that the criticism in these responses was meant to help you find a better solution and not anything else.

I wish you the best on your future knives, amigo!


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  #25  
Old 12-11-2005, 09:24 AM
fitzo fitzo is offline
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Bryan, another thought occurred to me: there is always the possibility that you somehow ended up with a bar of mislabeled steel even straight from Crucible. If you have a substantial amount left, the next blade would have the same problem in HT. Perhaps you could send a small tab to TKS for them to run and verify that, if done properly, the results meet expectations?? They would at least owe you that for a failed HT.

I understand your frustrations. I went to doing all my own HT many years ago. Now, if it comes out bad, I never have to wonder who the idiot is!!
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  #26  
Old 12-12-2005, 10:48 PM
Bryan McCall Bryan McCall is offline
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Talked to TKM today, but I will get to that in a minute.

The first two blades I made from this stick my Dad tried to heat treat at Bell Helicopter. We did everything correctly except use heat treat foil. They looked like the surface of the moon with so many pits. I kept them and put a nice edge on one. I use it around the shop for various stuff. I've shopped a couple of 2x4's with it and it still shaves my arm. They both tested out to 53, so I know it is not the piece of steel I recieved. I also talked to my Pops while he was at work and asked him about the testing machine. He told me the brand and model, which I can not even pronounce, but the main thing he said was that the machine is in the tooling bin. EVERYTHING in the tooling bin is accurate. These are the tools they rely on to build Cobra helicopters.

Talked to Alex at TKS. He put me on hold when I told him the situation. I assumed he went and looked at a log. Do heat treaters keep a log? Anyway, when he came back on the line he said that the proper procedure had been followed and that he did not know why it tested so low. He has offered to treat my next blade for free and test it before it leaves the shop making sure it tests at 58 or 59. I am skeptical but may send one anyway. I have an S30V blade ready to go. I also told him no hard feelings and suggested that he test all custom blades before they leave. I'm tired and am going to bed.

Bryan
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  #27  
Old 12-13-2005, 08:04 AM
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AUBE AUBE is offline
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bryan,
when you heat treated yourself were you aiming for 53? s90v and s30v should be able to hit mid 60's and is often used in the 58-61 range...53 is pretty low for most knife usage
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  #28  
Old 12-13-2005, 08:11 AM
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Don Robinson Don Robinson is offline
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I can't help saying that any blade should be way harder than 53Rc.

There's something very wrong here.
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  #29  
Old 12-13-2005, 08:14 AM
A T Barr A T Barr is offline
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Just for the heck of it, why don't you send that finished knife to TKM and let them test it?

A.T.


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  #30  
Old 12-14-2005, 02:11 AM
Bryan McCall Bryan McCall is offline
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Not sure why the two blades my Dad heat treated were 53, but I have a guess. One, the carbon was just burned up without the foil on there. Maybe someone can enlighten me on that one. Two, he could only get the oven to about 1975 degrees. Should be 2100-2150 for S90V. Also, he did an interupted oil quench. He has never quenched a knife blade before. On top of that, I gave him instructions over the phone from what I had read on the internet and this forum. 8o

AUBE---was aiming for 58 or so.

A T Bar----I asked Alex if he wanted the knife to test and he said no.

I'm going to let my Dad try to heat treat another but it will be S30V. This time he will use the heat treat foil and the required temp, 1950 degrees. He has to wait until a certain day when his foreman is not there. It had taken him a whole shift to get the oven to temp, treat the blades, quench them and be cool enough to put in his pocket on the way out the door.

I've decided to send this hidden tang blade (S30V) to TKM. I will be mailing it tommorrow. If they are working the week before Christmas, I guess I will get it back this year. I will post what readings Alex gets and what readings my Dad gets at Bell.

Bryan
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