Quenching Question clay backed, edge quenched?
Posted 17 October 2011 - 03:54 PM
Posted 24 October 2011 - 05:01 AM
What are you hoping to accomplish by that?
Before I would be interested in any type of "bend test" of such a knife, I am sure I would be doing some CUTTING TESTS! first to ensure I had sufficient hardening taking place.
It's more important that a knife cut, not bend.
Posted 24 October 2011 - 12:08 PM
Nothing could be less controlled and unreliable than what I just described but you can read about that type of heat treating in a lot of old blacksmithing texts. So your clay could maintain the heat that would lead to a tempering of the edge when you withdrew the blade from the quenchant. Of course the blade may never have made it to full martensite conversion since it may never had had a chance for the whole blade to air cool. Why would a smith trying to control each part of the heat treating process, do something that uncontrolled? Either a full quench with a fully austenized blade (clay) or only the exposed edge austenized and an edge quench. My position is the later of these two procedures has a few more risks but both are much better than full blade austenized with only and edge quench.
The goal is not ever just hard. It is refined micro structure, hardness sufficient to the intended task, etc. and a host of controlled processes to get there.
Posted 24 October 2011 - 05:21 PM
sorry for my typing,,baby in my other arm
Posted 24 October 2011 - 05:42 PM
Chad, reading this thread it may see like your getting shot down, and I wouldn't want anybody to feel like they didn't get a fair shake here. These guys know what they are talking about and are trying to help, but I thought I would give some encouraging input. I too would not pick this technique for myself and that is why I didn't post initially, I didn't want to seem too negative when you where happy with your own results. So I guess I would like for you to have your chance to feel at home here and be able to make your case for the results that are working for you. Is a vibrant hardening line one of your goals? And how does your clay method lines compare to other methods you have tried? How are the blades displaying their flexibility and how does it compare to other methods you have tried? I think Karl has a good suggestion on running them through some cutting tests.
One thing I would do is have some blades done in other ways and give them all a simple file test directly out of the quench before the temper. This is not foolproof but will give you some comparative hardness ideas. Next see how much hardness is lost for the tempering temperature. If one of your blades is cut easier by the file than the rest under the same tempering conditions it could have an excess of pearlite.
Be careful of putting too much into flexing tests before a bend, that two are very different and work in opposite sides of what is known as the stress-strain curve. Flexing, that is deformation that goes right back to the original shape when you let off the load, is almost solely a function of the metal thickness regardless of heat treatment; this is why I am not an advocate of the "brass rod" test as its reliability is somewhat overrated. Bending, that is deformation that remains after the load is removed is very much affected by the softness/ductility of the metal, which is much more affected by the heat treatment.
Just a few more tools to help in assessing your progress in your clay experimentation, I hope they help.
Posted 25 October 2011 - 03:29 PM
i have tried several tempering techniques and have chosen what I feel comfortable with having consistant results. I only asked if anyone else has tried this certain method because of my rainy day experiment. I use the file testing on every blade as well as a tip in the vise flex test searching for brittle blades.
This isnt how I make my blades just this one particular blade.
Thank you all for your comments
Posted 28 October 2011 - 09:01 PM
After reading the post of Kevin's I had to wonder if I was being overly critical. If so, I definitely apologize. You are doing exactly what most of us have done and, to some degree, still do. There is absolutely nothing wrong with experimenting or doing it different than everyone else does it. I read Kevin's post and what he said clearly is that experimentation may teach us all something as long as it is replicable and the tests of comparison are reasonable.
This whole ABS thing is about learning and the sharing of knowledge. That certainly does not mean that any of us know everything or have even tried everything.
Posted 29 October 2011 - 07:50 AM
i know far from everything and much less than most of you pros, but I'm learning and evolving on what I hope is my road to a one day mastersmith.
i follow your writings as well as other ABS masters and journeyman and its extremely helpful, but I feel like a copycat when
i follow anothers methods step by step, I'm always looking for my own way, but I know there is only one way to do some things successful
Posted 01 November 2011 - 12:56 PM
Please do find your own way. With heat treatment it is always knowledge and science that provide the foundation. Doing something different than what everyone else does is great as long as you can justify it with sound metallurgical principles.
For example, I might heat treat a blade with a temper line or hamon that is prominent using clay. In that same steel I might be able to get better grain size in relation to full or close to full martensite transformation if I heat treated the whole blade. The outcomes are different and I am willing to sacrifice some performance for esthetics. I do not claim one is better than the other even though I will describe the differences to a customer.
Recently, most of the blades I have finished have a bainite skin with a martensite core. A month from now I might heat treat a 52100 blade with rapid heat cycles starting with 1575 F on the first cycle going down to 1525 on the last. The goal in the last case might be aimed at grain size alone. A couple of years ago I was trying to get mixed bainite and martensite in a blade.
In each of those cases I broke the blades into segments and looked at the grain structure under a university microscope. In each of those cases I tried some cutting tests with a standard comparison blade I kept around trying to control geometry as much as I can as a variable. I will often keep doing the same thing until I think I have some control over the process. I also know that I do not have the lab equipment to do all the tests that would give me a measure of all aspects of the blade's performance. Most of the tests I do are relative in that this seems to do better than this or that. I am never going to know as much as I would really like to know (maybe when I retire I will spend more time on this sort of thing and learn a little more).
Where I am at is that I keep reading, listening to people like Kevin Cashen, and questioning what I am doing. I have done some really lame things in the past because I just did not know enough of the basic principles. Hopefully, I am getting better. In other words, find your own way and use science as foundation. If something seems to work, ask why.
Posted 01 November 2011 - 03:54 PM
Posted 02 November 2011 - 04:20 PM
Posted 03 November 2011 - 06:57 AM