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Heat Treating and Metallurgy Discussion of heat treatment and metallurgy in knife making. |
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#1
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heat treat troubles?
Help please, i just got a batch of blades heat treated by a Canadian heat treat facility blades were 440C ats 34 and s30v, Of the blades i have finished and sharpened they don't cut well in my opinion,and fail the brass rod test } edge deformes { .I have taken the blades to approx .020 before sharpening.They seem hard when testing with a file..The heat treater assured me they were 58-60 rockwell. I have not overheated while regrinding of sharpening.Have i done something wrong? What other testing can i do,they have offered to check them and redo at no charge .Any advice appreaciated.
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#2
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Allan: I'm assuming they were done as 3 batches, since each steel you list has it's own (different) HT cycle.
Without being able to check the hardness yourself, you are at the mercy of the heat treater. Can you provide any additional information about how these blades were processed? Temperatures, times, type of furnace, etc. all could be useful. __________________ Stay Sharp, RJ Martin Knifemaker www.rjmartinknives.com |
#3
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Heat Treatment
Being the kind of steel you mentioned that you had heat treated, there should be an indent mark on your blades indicating that they were tested for rockwell hardness. If there isn't any mark to indicate the RC test, you might ask them how they determined the hardness of the blades. Please let us here know how they turn out if they redo them for you and also who is doing the heat treating if you do mind.
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#4
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Thanks for the quick replies, R.J. I also am assuming they were done as 3 batches as they were cleary marked and invoiced as noted,i requested additional info from them but did not receive any other that they were hardened, cryogenic,and tempered..I am also assuming they have the correct equipment as it it a large company. Navajas, I have reground most of the blades but on the 12 i checked could find no indent marks.. The other items that have me question there operation is that the blades were wiped clean prior to shipping and came back with finger prints on them and they were cleary tempered with the blades touching one another as the holes for the scales were showing on other blades and the straw colour only shows on one side on some of the blades.Right now i am having second thoughts on returning them..Hope this info helps..Al.
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#5
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Commercial Heat Treaters
Heat treaters have bills to pay too. It is common for them to combine loads of material requiring "similar" time/temperature cycles to get the most weight per cycle. If your material was on the fringe of the cycle, you do not get the best heat treatment. That is just the way it is.
__________________ Which is worse; ignorance or apathy? Who knows? Who cares? |
#6
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Yeah, when I used a heat treater out here, I BEGGED them to do my S30V at 1950. They, BEGGED me to use 1900. Finally the discussion ended, with a "don't ask, don't tell".
Guess who won. But they did test each blade after tempering. Steve |
#7
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Quenchcrack,That's not good enough for me.If i sell a blade it has to me the best possible i can deliver, i realize they have to make a dollars and i question how they can do it so cheap 35 blades for $85.00 canadian funds i would gladly have paid more but they set the prices. I think you are correct though and i got the fringe end of a cycle.
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#8
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Allan: Blades touching during tempering or HT for that matter is not necessarily bad.
If you can find a local HT'r or knifemaker who has a good Rockwell tester, you can get a couple of blades checked and you'll know where you are. __________________ Stay Sharp, RJ Martin Knifemaker www.rjmartinknives.com |
#9
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Most heat treaters will stand behind their work , if they didn't they would not have any repeat business.
As for hardness test marks not every knife in a batch will necessarily be tested, when I take a batch of 50 or so in I expect that the thickest and the thinnest will be tested and if OK statistical probability predicts that the rest will be OK as well. A way to ensure accuracy on heat treat is to ask for oven charts when you send in the batch. These are provided to companies with ISO quality programs for trackability, what they cost I am not sure, there is probably an upcharge. __________________ george tichbourne www.tichbourneknives.com sales@tichbourneknives.com |
#10
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All the more reason to use Paul Bos, you will find a test mark on EVERY blade, he not only says that he tests every blade he dose it. Gib
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#11
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I agree on using paul bos. I have never been dissapointed with his work. And he charges reasonable prices.
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#12
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Thanks again for the replys.Cannot find any Rockwell tester on this island,However it seems i have solved the problem.Removing approximately .o40 from the edge i find the edge is no longer deforming.In future i will ask for each blade be RC however.
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#13
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Allan, with that last post from you, I would give an educated guess the blades were not cryo-treated, just said they were. I have no way to prove it, but SS blades in the past, for me, behaved that same way without the cryo.
Ken Beatty __________________ Ken (wwjd) http://www.wacoknives.com "One Nation Under God" |
#14
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I could tell you lots of stories about heat treaters but they are like any other group some good some bad. However with steels like S30V, ATS-34 and other complex steels the heat treatment is complex and critical.If you want the best performance it has to be heat treated precisely by people who are familiar with the steel and will take the time and care to do it right. BTW rlinger can heat treat it for you [I trained him !!]
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blade, knife |
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