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rob45
05-24-2011, 09:07 AM
During discussion in another thread, I finally bit the bullet and took the advice of Kevin Cashen and Doug Lester; I ordered some actual books on metallurgy in an effort to learn more about the mysteries of heat treating.

Metallurgy Fundamentals by Daniel A. Brandt was received in the mail yesterday, and I am already 1/4 through it. As usual, I will reread several times (long-term memory is created by repetition).
Also on the way is Steel Metallurgy for the Non-Metallurgist by John D. Verhoeven.

My time for reading is pretty much limited to my days off from work right before I retire for the evening (when daughter is in bed), about 15-30 minutes, but that also seems to be when I can relax and absorb the most.
But the way I see it, this is the next best thing to formal education, for which I have neither time nor money to do.


Thanks a lot, guys.
If anyone has any more suggestions on titles relating to this stuff, send 'em my way.

Rob

EdCaffreyMS
05-24-2011, 10:34 AM
I've read and studied both of those books, along with many other "heat treating" manuals. In all cases, my experience has taught me that the best thing a person can do is use those texts as STARTING POINTS. All too often folks expect printed information to be the "know all, end all" of metallurgy/heat treating. Don't get me wrong, there is a lot of good/useful information, but sometimes the gap between theory and practicality can be wide.
I can recall many years ago, being very frustrated because I was attempting to follow printed heat treating materials to the letter, expecting to achieve the results specified...seldom did it ever work out the way the texts described.
Once I realized that much of the printed material was based on theory and "education", rather than practical experience, I took the path of using the information presented as a starting point, and sought to take what I considered the next logical step(s). It takes time and effort on an individual's part, and for me, spending some $$ on spectrographing, but I have come to realize that although specific things may be mentioned/taught in print, some of those things may not necessarily apply, or may not even be desirable in the realm of cutlery. It's always good to educate yourself, but education without practical application/experience will often lead an individual into a "box" which can be difficult to find your way out of. The moral is to take everything you read or are told about heat treating (including from me) with a grain of salt, until you are able to prove/disprove it for yourself.
Hopefully that came out in the context intended....I'm not trying to bash any of the texts, or anyone who follows them....only lending my experiences from years of stumbling, and finally learning how to walk! :)

rob45
05-24-2011, 12:58 PM
I've read and studied both of those books, along with many other "heat treating" manuals. In all cases, my experience has taught me that the best thing a person can do is use those texts as STARTING POINTS. All too often folks expect printed information to be the "know all, end all" of metallurgy/heat treating. Don't get me wrong, there is a lot of good/useful information, but sometimes the gap between theory and practicality can be wide.

Hopefully that came out in the context intended.... :)

Ed,

As far as I know, I understand what you're saying.
I, too, am of the opinion that there is very little, if any, that can replace personal experience.

I never was in the search for a "heat treating manual", but rather a deeper understanding as to why different materials behave differently under different circumstances.

I see threads all the time on questions such as:
"What's the best material for a fillet knife? Does flexibility impact edge-holding performance?"
"Which steel is better for this type of knife, x, y, or z?"
"Do I need to do a hardness test? If so, which type?"
"Why is this piece of shop equipment so heavy? Will I still be served as well with a lighter model?"
"I got a great deal on some thick aluminum plate. Can I use aluminum for this grinder frame instead of steel?"
"I would like to make my knife stiffer, yet not as thick. Is that even possible?"
"I'm building a sawmill. Can I use a spindle off the junk tractor out back? The steel specified by the plans is too expensive right now."
"I see my buddy sharpen his knives on his bench grinder all the time. Is he really ruining them?"
"My buddy says not to buy those cheap files, as they are probably cheap steel that has been surface hardened. Does this affect how well the file will work for me? Or does it mean they won't last as long?"
"Why do some people do a differential heat treat on their blades? Do I need to do that, too?"

Based upon my personal experience, I can tell somebody the answer to most of the above examples. But let's say that I'm the one asking the questions- my next question is going to be "Why is that your answer?"
Or, we can reverse the situation- I'm the one giving the answer. Now the person asks me "What makes you say it won't work?"


Perhaps it was I who did not do enough explaining, easily leading for it to be taken out of context.
I'm new to the need for heat treating in general, and need to know why a particular method is better suited over another.
Or in a different perspective, why one would choose one material over another for a specified application.
Once I determine why, then I'll determine how.

I'm simply in the pursuit of more information.
Nobody can possibly have all the answers, and I am certainly the type who believes in proving something to myself before taking the word of others as "gospel", and this includes the writings of others.

But everything needs a strong foundation, as it is all too easy to build upon a weak one. Considering the projects I've undertaken in the past, I should have learned some of this stuff over 30 years ago.
So, like you said, such reference is a starting point to a deeper understanding in general.

In conclusion, I do not take you the wrong way at all; rather, I would like to apologize for not making myself more clear.:5:

Rob

Doug Lester
05-25-2011, 02:57 PM
Rob, I think what Ed is trying to say is that those books are not "how to do" cookbook types of manuals and that the industrial testing that they discuss has it's limits. Heat treating is talked about under specific conditions which may or may not have anything to do with industrial heat treating directly. For instance, the Jominy end quench test is good for comparing hardenability and hardness ofsteels quenched by the test method but that method of quenching is not used in production. Also, quite often the specific condition associated with a topic may or may not be all stated; usually it's the may not.

The ITT/IT/TTT diagrams are generated from data gathered by heating 1/4X 1/16" discs steel of a specific alloy with a specific grain at a specific austinizing temperature and then quenching them at increasing periods of time in a molten salt bath held at a constant temperature. The testing is then repeated at different heats at given intervals. We then take that diagram and impose the actual, or what we think/hope is the actual, cooling curve over it and estimate what the conversion products of austinite are produced and in what relationships with each other. Unfortunantly, most of us have to stick with guessing and hoping because we do not have the money to pay for rather complicated testing done on very expensive equiptment. Most of us can only test where the rubber meets the road or steel meets the 2X4, Manilla rope, brass rod, etc. This is only one instance where test data has to be interpreted to apply to real world production.

A hint or two, maybe more. Only read the black parts of the text. Don't assume things. If you read a statement like " retained austinite is converted to untempered martensite during tempering", don't assume that that is all there is to it. It can be converted to ferrite and carbides also; The text was just discussing the conversion to martensite, nothing else. Also a lot of the discussions will apply to specific size pieces of steel under specific conditions, like with the ITT diagrams, and often in pieces with different shapes and sizes than knife blades. You have mentioned that you don't expect to pick it all up the first time through the books. Well, you're not going to get it all by the 4th or 5th time either and you will need to discuss a lot with some of the real metallurgists who hang out on these boards.

I ran into a quote on another thread, possibly another board: In theory, theory and practice are the same thing. In practice they're not.

Doug

Knifemaker.ca
05-26-2011, 11:26 PM
In theory, theory and practice are the same thing. In practice they're not.

Doug

I LOVE that!!!!! :-)

clancy
05-27-2011, 06:11 AM
I think people are correct when they say "learn a particular steel and stick with it" this means testing, testing and more testing.

The number of variables is overwhelming.

first think of the steel formulation. the specs for composition allow variation so you have batch to batch variation and vendor to vendor variation.
next steel has multiple phases and you can't tell the status by looking, the phases in a piece of steel depend on it's thermal history, again something you can't see. Thermal history includes both the temperature and the rate of change.

All of these things taken together mean that to get the best results you need a large batch of steel that is all the same then refine your heat treating method based on real life testing. Something that few people will do!

ernie