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Jerrod Miller

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Everything posted by Jerrod Miller

  1. I'd suggest trying a sub-critical anneal (AKA extreme temper). Normalize it then heat again to just before the phase change and hold for a few minutes, slow cool. Don't get it too hot on the second heating, you're just tempering the structure that is there, no phase changes.
  2. And the phrase of the day award goes to Alan!
  3. Follow the links at the end of this thread: Specifically this one.
  4. The Cast In Steel project is great. They asked me to help judge the axes last year, but I was scheduled for other meetings at the same time. I'll definitely see you there then! I'll also be on a cast irons panel regarding mold media (silica replacements).
  5. Let's not be too hasty Gerald! That is border-line blasphemy. (My wife does not read this forum, I'm safe.)
  6. But if you were going to come to my foundry to make samples from our proprietary alloys, I can't guarantee that the samples I made are right, because I don't have a check sample to begin with! Seriously though, a good addition to that would be sending samples out to multiple resources to verify chemistry. I run a spectrometer round robin for the AFS 5D Committee, and I can assure you that no two foundries read the samples the same, and some are very different. Ensuring that you know what exactly is in your test sample for calibration/type standardization is the hardest part. Sounds like you guys should be thinking about presenting at the Casting Congress in April.
  7. In April the American Foundry Society's 5D (Specialty Irons) Committee is going to start working on making a set of standards like this to send out to the member foundries. It is nearly impossible to find certified standards in appropriate chemistry ranges. My point being, you have a great project, that is very relevant to industry needs. If you feel interested in making a Ni-Hard Type 4, samples I know a foundry or 2 that would like to get their hands on one that is relatively well certified. Chill casting is pretty much a requirement for alloy segregation to be minimized, so if you can ever find any standards they are usually 5 mm thick. Ever tried to grind a 1.25" diameter disc that is only 5mm thick? You'll lose your fingertips. And they still want to charge a couple hundred dollars for it! I just bought one today that is a whopping 0.75" thick, and it was $625.
  8. Just to add to Geoff's comments: Nothing good can come from welding the same material to itself with modern alloys, as far as mechanical properties goes. If you weld 2 dissimilar materials then you can get a blend of the properties. Forge welds are a source of potential flaws. When dealing with bloomery steel, weld flaws are much less likely to be a problem than the slag that is definitely a problem. Modern alloys don't have these slag inclusions in them, so you have no benefit to working the metal. The only benefit most modern forge welded materials present is aesthetics; which is important (ish), but not structural.
  9. Keep in mind that carbon is generally pretty bad for electric elements (so I'm told). So I would avoid that. Maybe a flux (in a bowl to protect your oven) would be a good idea? Or an argon or nitrogen purge.
  10. Yes they would. They were absolutely subjected to heat and forging, just not by you, but by the manufacturer. A couple normalizations would improve things, but may not always be necessary.
  11. Not quite. Everything you want to happen has happened. Holding longer will grow grains and possibly affect the carbides. This is why it is nice to know what things look like prior to the final heat treat. If the carbides look great, meaning they are appropriately sized and dispersed, you may not need to soak at all as you just have to convert the matrix (everything except the carbides) to austenite and then to martensite. Soaking is only to deal with carbides (or to grow grains if you ever want to for some reason). That isn't to say this situation is very common. If the metal was in a state that was workable for shaping, it probably wasn't an ideal final carbide distribution. But let's say you accidentally over tempered it. Then it is possible that a no soak heat and re-quench might be just fine.
  12. Oh, I see that I mis-read your first question. Sorry. I generally stopped playing with 52100 as I didn't have much, and even less time at the forge. In general I have had really good luck with watching for recalescence and decalescence to get steel to harden, regardless of alloy. Soaking will mainly just improve on the hardness and potential toughness on alloys that need it. I did not keep trying stuff to work out optimal soaks and such. Some day I will likely get back to that, but it will have to wait a few years at least.
  13. Thanks for the offer, but I am not currently set up for doing any micros (got a couple decently usable microscopes, but not the sample prep). Also, to be completely honest, I don't really care about these types of alloys enough to put any real effort into it. I don't think the benefits outweigh the drawbacks to them. Also, I just noticed that your soak time was supposed to be 15-30 minutes based on the spec sheet. And I don't think you have to cool this down too terribly quick, so oil in the foil is probably fine, though it will probably be hard to ensure that it is even enough to prevent cracking, especially since the oil is supposed to be interrupted at 1000F.
  14. Yeah, soaking for that long at that temp is pretty much going to require protection from oxygen. 304 foil holds up better thanks to the Ni in it, which helps for higher heat. S35VN is designed to be used with optimal HT equipment (given the previous discussion, vacuum seems to be their intent). There is a lot of V (and thus VC) in there, and those do NOT like to dissolve (same with Mo and MoC). That is why the high temp for so long. It would be interesting to know what the microstructure looked like from the manufacturer. If the carbides are fine and well distributed, then an extended soak wouldn't be necessary (assuming stock removal only).
  15. My comments above are just basic metallurgy, nothing specific about 52100 (though it is about having a bit of C and Cr in the alloy).
  16. Joël covered it pretty well. Thermal cycling is important to grain reduction. Temperature right before quench is a much much smaller part for grain size (assuming your temperature is reasonable, if you are nearly molten then grain growth will be pretty big).
  17. It sounds like you did indeed use the terminology correctly. The best example I generally have to describe shear is to place your hands together (palm to palm), then slide them as if you were trying to warm your hands. I think this is the key. While it is a weaker weld, there is a lot more of it to spread the load. Like the chain link example, if you scarf a lot of material, you have a lot more area of weld to hold it. Whereas if you do very little scarfing, you will want something better than a forge weld (like an electric arc weld, possibly with a better material filler than the base material).
  18. Depends on blade sizes and alloys. Smaller mass means less heating of the oil, and some alloys are much more forgiving on oil temp, so you can start cooler and end hotter. It also depend on how quick "back to back" is for you.
  19. .30 cal ammo can dimensions 30 cal ammo can is approximately 11 inches long x 3½ inches wide x 7½ inches high and weighs about 4 pounds, 8 ounces when empty. .50 cal ammo can dimensions Military "M2A1" Ammo Can 50 Caliber New 11" x 5-1/2" x 7" You can guesstimate internal dimensions from there.
  20. I use a bread loaf pan, and pour the oil back into a plastic container (once cool) for storage. Pans like that can be found at the dollar store, so it is super cheap and effective, and if you are needing to not over-heat oil, just have multiple pans! This could work for ammo cans, too. And remember that ammo cans come in various sizes.
  21. For the record, this isn't a thing. Good steel does not have any pores. My first thought for a suggestion was to make beads (weld splatter is a good starting point, but they can be shaped later if needed/wanted) and then solder/braze them on.
  22. I was under the impression that shear is where a forge weld is weakest. All metals are weakest in shear, in fact the shear strength is half the tensile strength.
  23. Again, not trying to pick a fight, but I'm not sure I agree with this blanket statement. I should clarify that I meant only in regards to these materials. There will of course be things that are not yet on OSHA's radar. But these materials have been extensively tested and proven to be quite safe.
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