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Jerrod Miller

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Everything posted by Jerrod Miller

  1. No, yours looks pretty good. Mine is insanely fine, which is why it has been on my desk for a couple years now. There is absolutely no need to get it like that. And to be honest, I have no idea how it got that way. When we first shake these out we hit the risers to break them off and the grains can be measured with a ruler! I don't have a chunk of that at hand to get a picture of, but I will try later. If you need any magnification to see the grains you are doing good.
  2. BTW, that was from a 1000 pound part that is an air hardening alloy. This is why some modern cast anvils can be so much better than older anvils (we only produce the one tool steel here, at this time).
  3. Generally speaking, for the grain sizes we want I would be inclined to put it on the metallographic microscope with 100X objective and 15X eye-piece (1500X total magnification). To prep for that there would be lots of polishing down to a felt wheel with a 0.5 micron or smaller diamond powder slurry, then etch with 2-7% nitric acid in ethanol (aka: Nital). It will look something like this (this is a look at a case hardened part): Note the scale bar. So really, a bit less magnification would be fine. This is about what you need to measure the grain size for an actual class
  4. It was suggested several times! I have even seen it hanging on a lobby wall in a couple foundries. It is kind of an in-joke with those that pour stainless. Everyone knows it happens and that it can look quite cool. It is often just too much of a mess to deal with. It is usually a horribly awkward size/shape, with lots of sharp poky bits. We never have that issue at the foundry I work at now. Nope. Never.
  5. It is an unfortunate thing that some of the coolest looking things are because something went wrong. Stainless steel that leaks out of a broken mold can look amazing, like a piece of modern art; but in the foundry it looks like a production loss that is quite expensive. Same with this weld flaw. Unfortunate for the blade maker, but cool to look at none-the-less. Also, the scope I have on my desk at work doesn't get pictures that clean. Very nice.
  6. They are all over the place, depending on manufacturer, but generally not overly high in carbon. Your snow quench isn't doing you any favors. Snow is a terrible quenchant. As for the tang transition, the key is to fix it as you go before it gets too bad.
  7. FYI, I buy what we call ingot iron or cathode iron (depends on the vendor) for work regularly; I like to keep at least 1000 pounds on hand at all times. A sample chemistry is below. This stuff is readily available, but not overly cheap. We last paid about $1.12 per pound for a ton of it, so about 6x the price of our mild steel (we buy pretty nice mild, there are even lower grades that would be cheaper). We just use it when we need to dilute something in the melt bath, usually carbon.
  8. I was commenting over there when you posted this. Thanks!
  9. Thanks for putting this together Joshua! It looks like your corners are not welded shut on your crucible, and the foil is just folded over. Is this accurate? I would have thought that the molten metal would leak all over the place. Do you find this to definitely not be an issue? This seems so much easier than I would have thought if that is the case.
  10. That sounds like a fun WIP type post for the non-ferrous sub forum. I know I would like to see any cool tips for getting the foil to line the steel box without getting gaps or folds that make things awkward, as I would totally not do it well.
  11. I've seen that mentioned as the reason before, but I am not convinced that is the case. Think about how clean the weld surfaces have to be for a good weld. I think anything that will form a non-metallic barrier would likely work. Killz is only 5-15% TiO2, per the SDS. There is a lot of other stuff in there that is going to leave behind a film (burnt paint ash). Though there is a lot of water in there (25-35%) that will evaporate away, making the dried content of TiO2 higher. This is just my speculation at this point. Geoff's tests will add to the knowledge on this. I just had to watch
  12. Now you're talkin'! Looking forward to seeing the results!
  13. I, for one, would love to see your results. What can we do to encourage you to try? Should we give you loving encouragement and affirmations? Or should we mock you relentlessly as a coward to light a fire under you? Either way, I'm sure we're all here to help in whatever motivational support you need.
  14. Billy's picture is a great example. Note that the 3x Normalization is after the bad heat control. So if you never let your grains get that bad to begin with, then 3x normalization will get you even closer to the last sample. And your sample looks to be pretty fine, though as Billy mentions, it looks pretty thick. Untempered steel is extremely strong, it just doesn't take kindly to bending. So to get it to bend, and subsequently break) thinner is easier. It is also ideal if your test coupon has a cross-section similar to the blades you make (so add the bevel first). Overall, good work!
  15. Pattern making is pretty different from standard carpentry or cabinet making. You'll definitely want to check with the foundry to see what their pattern requirements are. They may even be able to do it via lost foam, which would mean you just have to get a big block of foam (you can super glue a few blocks together) and carve it yourself. The foam is packed into the sand and burns out as they pour the metal. Not too many foundries do this though, especially on that scale (hard to capture all the bad smoke coming off of that). If you had a drawing/3D model made of what you want, that would
  16. Electric supply places may be able to help, too. Industrial bus bars can get pretty big. Places like Graybar may be able to get you what you need or point you to a local contractor that may deal in scrap components.
  17. It also occurred to me that I should point out that a fluidized sand bed can make a pretty good quenchant. Use it at room temp for when you aren't sure if you want to rink an oil quench but aren't sure if air is fast enough. Obviously this is only of use for a select few alloys.
  18. It would be great if you have a thermocouple probe to stick into the sand to see what kind of variances you have (with and without a test blade in there). I would worry about things not being as even as desired. I hope you get something that works. Salt pots are on my "someday" list, and I would really rather not have molten salt, but I really want the control.
  19. Heating and cooling sand is a bit of a big issue in foundries, and I have done a lot of work on it. With that being said, I would not think a fluidized sand bed would be a good choice for heat treating. Thermal conductivity of sand isn't great (some much more than others; chromite being much more than silica, for example). So you would have to be really stirring it to ensure you actually are getting an even temperature. And stirring it with cold air only makes the problems worse. So now you have to start looking at heating your air to HT temps before it hits the sand. And then you have t
  20. Welcome! Fair warning: You have taken the first steps down the rabbit hole. Before long you may find that you are looking to mine some ore, smelt your own steel, and forge axes (or anything else) from it. You have been warned. To answer your questions: You don't actually want to anneal it. That requires really knowing the alloy at hand and cooling from above critical temperature (often 1550-1600F) in a controlled fashion (e.g. 20 degrees per hour). What you really want to do is normalize it. That will remove almost all the stresses and put it as soft as you are going to n
  21. No. They are going to be ductile/cast iron.
  22. I do! It is based on the number of grains per unit of area, as measured in an optical microscope. This is done by polishing a cross-section and etching it, then going in and taking a look and actually counting grains. It is only really a valid number when the grains are relatively uniform in size and distribution. The old formulation was N = 2^(n-1), where N is the number of grains counted at 100x magnification per square inch, and n is the ASTM grain size number. My understanding is that there is a new formula, n = (3.321928*log10(N))-2.954 where n is the grain size number, but now N is
  23. I saw that, but I don't think that is correct. The second page of the sheet is the same as the first page, with that chemistry listed under 135Cr3 both times. I think they have a glitch and are missing the second page with the actual 130CrV3 info. Also, anything with a V in the name like that should have at least 0.10%V, and much more likely to have over 0.20%V.
  24. For what it is worth, I could not find any compositional information on 130CrV3, but did find 135Cr3. I saw it referenced as similar to W2, and I heartily disagree with that comparison.
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