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Heat Treating and Metallurgy Discussion of heat treatment and metallurgy in knife making. |
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#46
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Hey! I be 55, that's not fair that Fitzo's younger than I am! (well, physically, anyway, I got him beat mentally )
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#47
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Quote:
I must be getting feebleminded if all I can do in response is funny little faces! |
#48
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Fitzo, over the hill gang here! speak for your self, you need to get to the top first I am 68 and not there yet. OF#2
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#49
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Jeesh, Gib, what was it like before the rocks got ground down into dirt???
I wish I had your energy, and I admire your work ethic. My problem is not so much age as being broken down, but, I am better than I was two years ago, and hope to get back to where I can really work again. Really hoping I can be happily walking over that hill rather than dragging myself. I'd like to be able to honestly call myself a fulltime knifemaker, as this head still has lots of ideas. Every day I wake up on the right side of the grass is a Blessing! |
#50
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"I taught Materials Engineering for 2 years at the University of Texas-Permian Basin. "
Bob, I wish someone with your ability to communicate had been teaching here at A&M when I took material science grad classes! Unfortunately it was usually a professor who didn't want to take time out from research to teach doing the lectures and grad students who scarcely knew more than us(the only requirement seemed to be that they had taken the class the semester prior) *teaching* the practical lab sections! I enjoyed the classes and learned quite a bit...but I think they could have been much, much better. I enjoy reading yours, Kevin's and several others on various forums posts about metallurgy and find them quite useful. Thanks! |
#51
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Mike, There was a time few years ago when I couldn't do a lot but with the help of a good Dr. and a lot of hard work I am 2 or 3 times better. I was so bad I went and sold all my Cowboy Guns, last year I bought another set and now shoot in CAS matches every month. Talk about fun beyond belief. Gib
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#52
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That is inspirational, Gib, thanks!
My biggest problem seems to be to motivate myself anymore. I developed a mindset of inability when I was at my worst. When I do work, I tend to overdo it and "hurt" myself, sending me back into the lassitude. I need to re-discover the joy and passion in knifemaking (or for that matter, anything) that I once had so that I do what I can, every day, instead of once in awhile. Dealing with illness mentally is as difficult at times as the physical limitations. |
#53
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Mike, I found that it was a matter of want to, anyway I get bord with nothing to do and my hands need to create. Gib
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#54
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You're absolutely right, Gib. It is something I can only do for myself. Thanks for the honest reminder!
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#55
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Communicating
Don, Thanks, I appreciate the encouragement. I wish I could make knives like the rest of you folk, too!
My first class at UTPB had mostly juniors, mostly from Iran (I am dating myself now) and none had taken calculus, chemistry, or strength of materials. I ended up having to teach a vocabulary course since none of them could actually do the engineering! __________________ Which is worse; ignorance or apathy? Who knows? Who cares? |
#56
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Just my 2 cents, but I think the cutting competition in the abs has a few people rethinking how they heat treat blades. I got to see my first one at the hammer in in old washington a while back and heard a few smith's talking about changing a few things from what they learned from the cutting competition. I was taught to fully harden the blade and draw it back on the spine back in the late 80's early 90's. And that is exactly how Mr. Connor taught it at my basic bladesmithing course in 2002. We had one fellow from wisconsin with a bowie we couldn't bend. There were three of us with a cheater pipe trying to bend it. Mr. Connor stopped us because we were either going to break the vise or when the knife did finally break someone was going to get hurt. Quite a few people were impressed with that blade. I prefer to fully harden them because you can draw back the spine to the stiffness best suited for the intended purpose of the knife. From either a sharpened pry bar to springy fillet knife. It's up to you.
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#57
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Diferential Tempering
Jimmy, I am with you. I think a fully hardened blade is superior for these reasons: the blade has less tendency to warp and crack in the quench, the martensitic spine, even if it is drawn down to an Rc 22 is tougher than a ferrite/pearlite structure you get when you do not fully quench the whole blade, quenching only the edge and leaving the spine hot slows the heat transfer at the edge and lowers the as-quenched hardness, and two microstructures in one blade can create a galvanic cell and cause corrosion (a small hazard if you take care of your tools).
A friend of mine has been picking my brain for a way to get martensite on the edge and bainite on the spine. To hit the bainite curve, you need to quench to about 1100F,stop the quench on the spine and slow cool it while continuing the quench of the edge. This probably means quenching the entire blade to 1100F, then pulling the top of the blade out of the quench while leaving the edge in all the way down to ambient. Low carbon bainite is incredibly tough but I am not sure if it has an advantage over martensite in a high carbon steel. Has anyone tried this? __________________ Which is worse; ignorance or apathy? Who knows? Who cares? |
#58
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Howard Clark acheives this in some of his L6 swords, bainite spine and tempered martensite edge. If I understood an email awhile back, it is a two-step process. That's all I know.
Interesting about the galvanic difference in the two microstructures. Dissimilar metals I was well aware of, but not this. What an excellent thread. Thanks, Bob and everyone! |
#59
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I read somewhere not long ago of a guy that quenches the entire blade for "X" length of time, then pulls it out of the oil, and if it's still smoking, in it goes again. The out again, and if it's not smoking, I think that only the edge goes back in until the oil temp is reached. His procedure may not have a thing to do with the hard edge/soft spine discussion, just something I remembered. (At my age, if I remember anything at all, you guys are going to hear about it!)
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#60
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Hard Edge, Soft Spine
Hmmm....starting to get personal here.....hard edge, soft spine.................
I wonder how much of the "mystery techniques" are founded in just not knowing a darned thing about what is going on at a microstructural level. Yep, experimentation is a very important thing but I get the feeling that a lot this experimenting is just floundering around. Now I would be the first to agree that a lot of metallurgy started out this way. However, we have learned a lot since the age of iron and we can certainly shave a few years off of someones learning curve if they are willing to ask a few questions, eh? I have been known to quench 5160 in water by succesive quick plunges into a slack tub trying to get a slower quench rate than water but faster than oil. It works rather more frequently than seldom but not as often as occasionally. I was asked by a young neighbor boy if I could repair his diving knife. He said he bent the blade on a coconut. I said "sure, bring it over." It was a very inexpensive diving knife and on the blade, it said 304 SS. 304!! 304 has a nominal carbon of .05%! He could have bent the blade slicing bananas! I hammered it back into line and polished it up for him. I did not tell him the knife was a POS. He was about 12 and very pleased to get the knife fixed. __________________ Which is worse; ignorance or apathy? Who knows? Who cares? |
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blade, forge, forging, knife, knives |
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