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I Forge Iron

GrayR

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Everything posted by GrayR

  1. Glenn - Thanks for the advice. I will consider how best to put it together.
  2. Re: Matherton Forge -- great site, nice work. I haven't seen it before. I will spend some more time there when I get a chance. My original posting came from a discussion a couple days ago, and then some late-night searching at this and bladesmithing websites and the magnet trick comes up frequently. Re: QC frustration. OK, I've seen your name many times, and your posting quota indicates that you provide frequent advice. I posted a straightforward comment, one which you agree with in concept. You provide a comment in disagreement on what smiths need to know ("since close is good enough to most folks. . .) . . . and I disagreed with that (and still disagree). After that its gets pretty frustrating for me too -- "remember this is blacksmithing . . ."; I'm shown the Blueprint on metallurgy (I guess so that I can understand what blacksmithing metallurgy really means); my experience is questioned; then it is recommended that I write my own Blueprint; and finally "your (my . . .) mistake is . . ". I'm not trying to put you on the defensive (if that was your point in your last posting), and have even praised your work in these postings, but . . . . Re: "very same issues will be discussed next year by the new people . . ." that was my reason for posting in the first place. I know that it isn't new information . . . I never said that I invented metallurgy. New people probably come to this site daily(?), and look for advice. If they did a search, they would see my posting (or one of yours, or someone elses); or if they post, then someone who previously had misconceptions about heat treating could respond accurately. I think first grade teachers and college professors get the same questions every year, but at some point, some of their students get it, and take it to another level. I guess I didn't know the rules for this Forum -- don't post a fact or advice until someone asks for it. Re: Knifemakers understand metallurgy better than blacksmiths. I disagree with that as well. Cashen (based on his website) and some others probably know better; but I see off-base advice on bladesmithing sites as well. Good luck.
  3. Re: ApprenticeMan. Thanks. No axe to grind . . . just responding to the comments, and trying to get the right information out there for reference. Again, QC has good information on his posts -- and, if I didn't say it earlier, the Blueprint has a lot of good (and accurate) information. But I do agree that better information would raise the bar.
  4. Umm . . . actually I was not taking issue with your blueprint, more below. Re: Recrystallized Controlled Rolling -- yes, it is done, but as you said to me earlier, blacksmithing vs. met. eng. -- RCR was not mentioned in the Blueprint concerning the deformed grains in Figure 6 right, so I was providing was happens during the normal forging process. Again, it wasn't an issue with the Blueprint, I think that everybody learns from everybody else, just like you did. That is the reason why I do come to this website (it wasn't my first time here . . .) You took the time to write it down on paper, so that is good for you (and for the blacksmithing community). But to be honest, concerning the Blueprint, my metallurgy classes didn't identify Fe-C phase diagrams and ITT/CCT diagrams as maps (maybe yours did), but I did go back to my 1994 Anvil's Rings (21 - #3 & #4) and there was an article on heat treating that does refer to metallurgy maps -- so maybe we all learn from each other -- and that was the point of my original post. BTW -- Gray is not a name, but my hair color; maybe you don't have as many years as you think.
  5. Re: metallurgical eng. vs. blacksmithing -- know the difference. The blacksmithing started years before the metallurgy. I think at some point, we need to get away from the incorrect information (not necessarily in your work, Quenchcrack) dispensed by many smiths. The Curie point doesn't indicate the change from BCC to FCC, but is a separate phenomena -- what is so hard about explaining that to the average guy that wants to get better? Re: BP0078 -- have looked at it before and overall very good and correct*, and gets to the point I was making before about providing factual information to the blacksmith. Good job of explaining the metallurgy in a simple manner. Linking the Curie point with BCC-FCC transformation for .5 C steel just confuses the metallurgy. But, again, very good. (* The description along with Figure 6. True hot forging occurs above the Ac3 temperature because the FCC structure deforms much better than BCC because of more slip planes. Since recrystallation begins quickly above Ac1, anything that is hot forged recrystallizes almost immediately (seconds -- again, I don't have a ready reference), so there should be no deformed grains as shown in Fig. 6 after hot forging.) Re: carbide dissolution. I don't have a reference at hand to disagree with your point, but I don't think carbon diffusion is as slow as you are indicating. FCC iron is pretty accomodating to movement of carbon. I have seen instances of increasing the austenitizing temperatures 50 degrees, or lengthening the soak time a few minutes eliminate any of the dissolution problems. I think the bigger problem is breaking up of alloy carbides. Again, I would be interested if you have a reference (may help me in another area). Re: Soak time vs. section thickness -- again, don't disagree, but someone else brought up cutting instruments, so I was going along with mostly thin parts not requiring lengthy soak times.
  6. OK, makes sense for the average guy, but if someone is selling a knife blade for a few hundred or a thousand bucks then it doesn't make sense anymore. There are probably some pretty good bladesmiths or toolmakers that are trying to make a living with their products and they don't understand why they get inconsistent results. What I don't see in the postings or the recommendations is, 'steel will lose its magnetism as it begins to transform the ferrite to austenite, but in many cases this heating point is too low to harden or normalize.'
  7. Probably OK for the .80 - 1%, but if you are using 4130's, 4140's, 5160's etc., then it may harden poorly. If someone is investing $ in alloyed steel, then it seems to me that they should invest a couple bucks to know where they are quenching from. Likewise, I have seen many on this site that are trying to make quick, single use tools from lower carbon steels, so it would even make more sense to get it up around 1700 degrees. As far as carbide dissolution, in most alloys, the carbides dissolve very quickly. In tests that I've seen on moly/chrome alloyed steels (trying to get 50% martensite at mid-thickness, >1" thick) the carbides dissolve in a few minutes. Some of the tool steels need a longer time, but 10 minute soak at temp. will probably get almost everything. But in reality an extra 50 to 100 degrees will do more than another 20 minutes at soak.
  8. Yes, you are right. Tempilaq has some advantages over the stick.
  9. After reading many posts in this website on heating steel to nonmagnetic for normalizing or quenching, please be aware that steel (actually iron) loses magnetism around 1400 degrees (Curie point). The lower critical temperture for steel is 1333 degrees, and the upper critical temperature varies with carbon content. For pure iron, and low carbon steels, the upper critical is well above 1650 degrees. The upper critical temperature decreases as carbon increases, and for 0.83% carbon, the there is only a single critical temperature (1333, the eutectoid point). Between the lower and upper critical temperature, steel is transforming from ferrite & typically pearlite into austenite. This transformation is dependent ON TEMPERATURE, not time. That is, just above the lower critical (i.e., 1400 degrees) only a small amount of ferrite is transformed, and holding at this temperature does not convert any more ferrite to austenite. (There is a method called the 'lever-rule' that can be used to determine how much transformation has taken place at each temperature.) The point of this is -- you can only harden or normalize austenite. If only 10% of the steel has transformed to austenite, then at most only 10% of the part could (assuming quench conditions are right) harden. Since the Curie point is only about 100 degrees above the lower critical for most steels, heating only until the steel is nonmagnetic, only a portion (and in some cases, only a very small portion) of the ferrite has transformed to austenite. And the part will not be able to harden properly. To properly harden you really need to be about 200 degrees to 300 degrees hotter than the Curie point. Manufacturers sometimes recommend slightly lower temperatures for the higher carbon steels, but heating to 1600 degrees will not cause a problem. Use a Tempil stick or something similar to test for the right temperature.
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