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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 Literature
can anyone recommend some good books that i can pick up for heat treating high carbon steel?
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#2
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I would recommend Metallurgy Fundamentals and Steel Metallurgy for the Non-Metallurgist. The first is a little less technical and helps more with using carbon phase and isothermal transformation diagrams. I deals a little less with what goes on during various processes but more what the processes do. The latter is more technical; describes what goes on at the molecular level more. It also deals with just ferrous metals and was written more with the knife maker in mind. Both are very much text books written to be studied. Both are around 200 pages and each seems to compliment the other's weaknesses. Both can make your head spin. I would recommend that you get them both if you can. I'd choose the latter one if I had to choose. Kevin Cashen prefers the former book.
If you are just wanting data sheets for heat treating you can go to ASM International and subscribe to their reference service. I cost nothing to sign up, though you can choose to join their society. For small fees, $10-15, you can download data sheets and short articles to your computer. It beats laying out about $350 for a book full of steels and only a few of them usable for knives. Doug __________________ If you're not making mistakes then you're not trying hard enough |
#3
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To add my input to Doug's, something you need to be aware of, is this....
Any heat treat manual or other printed material...be sure to read the preface, and "lead in" before diving into the book. It has been my experience that many will dive right into the information (especially if the book is a "heat treat manual" and never realize that the figures (temps and times) are for a specific size piece of the described material...usually a 1" cross section (this means a cube 1"x1" X1"). Although some may disagree, experience has taught me that there is a distinct difference between heat treating that 1" cross section, versus a 1/4" thick blade of the material. The reason that I am saying all of that is so you will understand why I'm saying what I'm about to.... Even though there is a level of "science" to heat treating, it's also going to require a level of experience. What I mean by that is....use the printed data as a STARTING POINT, not an absolute know all, end all. Some call it "tweaking", others might totally disagree, but it takes time, experimentation, and some experience to "find" the heat treat that YOU desire. In a perfect world, with no variables from shop to shop, it would be great to be able to follow a written "prescription" but it's just not that way. All I'm saying is take it one step at a time until you get the "feel" for it. __________________ WWW.CAFFREYKNIVES.NET Caffreyknives@gmail.com "Every CHOICE has a CONSEQUENCE, and all your CONSEQUENCES are a result of your CHOICES." |
#4
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#5
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Even some of the manuals state that there is a difference between heat treating a 1" thick, or thicker, piece of steel. For one, when you get down to 1/4", or there about, there is little difference between the rate of cooling between the surface and the core of the steel. I also have the feeling that the rate of cooling, in general is faster. A greater percentage of the mass is exposed at the surface which exposes more of the mass of the steel to the quenchant.
When reading the data sheets realize that you are taking what happened to a certain alloy, of a certain dimension, under certain conditions and try to estimate what will happen under different conditions. One of the biggest places that his happens is with the isothermal transformation diagrams. Wafers of steel, one book I have said 1" round and 1/16" thick, are austinized at a stated temperature then quenched to a temperature below lower critical for set intervals and then quenched below Mf. The resulting crystal structure is then interpreted back to what must have been present before the last quench. That interpretation depends on the judgement of the experimenter. This is done with hundreds of wafers at a range of temperatures over a range of times. The lines of the diagrams, the solid ones, are actually more of an average of data points. When you get to the broken lines in the diagram you are dealing with estimated data points or areas where there are too wide a variance in results to plot clear points. Then, to make things better, we project what we think/hope/pray what the actual cooling curve is over this and try to interpret what will happen with a larger piece of steel, of probably a slightly different make-up, probably a different grain size, possibly starting at a different ausinizing temperature, treated with different equipment and quenchant, and then try to figure out what will happen with a specific blade. You end up with plenty of wiggle room. What Ed said about that information being the starting point was stated quite clearly in the preface to a book of IT diagrams that I have. Pay more attention to the principle and physics of heat treating than the examples of specific results gotten with test material or hypothetical examples. Doug __________________ If you're not making mistakes then you're not trying hard enough |
#6
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CJS...Some of the steels we work with are listed as being shallow hardening. If you are using a 1" x 1" x 1" cube as a "standard" then that information may be significant. With knifemaking, where the thickness is obviously much thinner, the fact that the steel is shallow hardening becomes irrelevent, since for our purposes, the blade will through harden.
The reference manuals must use some dimension and temperature as a basis for their information, in order that the information is valid, but when that dimension is changed by our specific use, then the rules can and do change....and this is where the experience comes into play. Real world situations demand that we take something from both the "hardened technical information" side and then "temper" that information with our personal experience, and our specific use. If we were use a properly heat treated blade for a "standard" for technical analysis, then our findings would not be correct for a 1" x 1" x 1" cube....and yet it would be correct analysis for our blade. To get the maximum benefit from the technical information that is available, both the information presented and our personal experience must be taken into consideration. If this is done, the technical information may seem to be at odds with our experience, but the reality is that both the technical info and our personal experience can be correct....it's all a matter of context. |
#7
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If it is any help I have included heat treating guidelines for many steels, and with the appropriate considerations for knives, at my website here: http://www.cashenblades.com/heattreatment.html At the bottom of that page is a list of common carbon and tool steels, click on them for the info. |
Tags |
52100, bearing, blade, heat treat, knife, knifemaking, knives, material, project, steel |
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