[Chad Harding]

Just a question, has anyone ever clayed up a blade then only edge quenched? I've heard of edge quenching from a full heat,edge quenching from a selective heat and full quenching from a clayed blade. I have done this a couple of times and seem to be getting great results from 5160, very clear temper lines on test blades so far. havent done the bend test yet but seem flexible.

[Karl B. Andersen]

I guess I do not understand your intention. Only edge quenching a clayed blade will result in the spine holding heat for an unnecessary amount of time. You will have residual heat in the spine that will take a long time to dissipate and possibly influence your cutting edge adversely.
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.

[Dan Petersen]

As Karl pointed out there is a risk to heating a clay coated blade to the critical temperature (whole blade) and then only edge quenching. Chisels were sometimes heat treated in this fashion. Three or so inches of the chisel was heated to the critical temperature but only about 1.5 inches was quenched in oil. At some point the blacksmith assuming close to full or full martensite conversion in the tip would pull out the chisel and allow the retained heat in the upper few inches to travel down to the now harden tip. The tip would then go theoretically from 100 degree F to a tempering heat of 500 degress F or better. All somewhat 'guesstimated' by the blacksmith.

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.


Dan Petersen

[Chad Harding]

well , like I said just experimenting, but i clayed a blade like normal then only edge quenched it, then soon as color was gone fully submerged it in cold oil. triple temper, 400, 350,350, edge holding is great, wood chopping,bone,sheet metal. no chip out still sharp. like I said very clear temper line, upper spine cuts with a file easily, last test is bending. great finds are from curious experiments, I'm not claiming anything just playing around with methods


sorry for my typing,,baby in my other arm

[Kevin R. Cashen]

Chad Harding, on 17 October 2011 - 05:54 PM, said:

Just a question, has anyone ever clayed up a blade then only edge quenched? I've heard of edge quenching from a full heat,edge quenching from a selective heat and full quenching from a clayed blade. I have done this a couple of times and seem to be getting great results from 5160, very clear temper lines on test blades so far. havent done the bend test yet but seem flexible.

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.

[Chad Harding]

No Kevin, I dont feel shot down, I know what everyone means and I have done extensive testing over the years with my blades and have used the "proven" and "Preferred" heat treat methods, for differant steels.
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

[Karl B. Andersen]

Chad, I see you are in Indiana - whereabouts?

[Chad Harding]

Just a few miles outside of Bloomington Karl

[Dan Petersen]

Chad,

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.

take care,

Dan

[Chad Harding]

Dan, no worries here,
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

[Dan Petersen]

Chad,

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.

Dan

[Kevin R. Cashen]

I should apologize since this chat is actually doing fine and the only reason I added some sugar to the thread with my post is that I have seen the effect that the impersonal nature of the written word in forums can have on folks. This forum can be a tool that brings many new folks to the ABS, but unfortunately I have seen people decide to turn their back on an entire organization over some very petty things. Some would get two posts not in support of their idea and get their nose bent out of shape, take their ball and leave. Fortunately, Chad is not the average internet poster who is merely looking for validation, he has exhibited a very keen interest in exploring both the positives and the negatives like a true scholar would, but I was just playing it safe by hearing him out. So I would say, just ignore my fretting and carry on with what looks like a pretty good conversation.

[Chad Harding]

Thanks Kevin and Dan, seriously I would give my right arm to attend "intro to bladesmithing" and the other classes as well and attend some of the big hammer-in and other blade events,, its just not in cards right now,, so I do what I can by exploring every angle of the craft and the ins and outs by myselfand finding out first hand what works and doesnt. The amount of talent on here and in the industry is outstandingn and I cant wait till I can learn and contribute more. The ABS in my opinion is the only way to achieve what I'm after .

Thanks Chad

[Kevin R. Cashen]

Chad, I am about 6 hours north of you, you are welcome at my shop anytime. Rick Barrett and I get together to have fun in each others shops quite a bit and Goshen is not quite as far from you. You are a few years too late, James Porter used to be near Bloomington and was one of the best I had the priviledge to meet. Jim was the mastersmith who hosted me in both my Journeyman and Master tests, but we lost him to cancer a few years back.