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Jerrod Miller

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Jerrod Miller last won the day on October 20 2023

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About Jerrod Miller

  • Birthday 03/25/1984

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    Jerrod Miller 25
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    Near Spokane, Washington
  • Interests
    Steel metallurgy, HEMA, forging (blades and otherwise).

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  1. To add on to Alan's great response... The surface of the material definitely should be free of rust before testing. They are ever so slightly better than Alan is saying though (usually I'm the one saying that they are pretty worthless!), in that it should also be able to help sort between major alloy groups. For example, between 304 and 316, it should pick up the Mo difference. And it should get close enough to tell if something is mild steel vs 41XX or 43XX. I definitely would recommend ignoring all hand-held XRF readings for anything remotely important. They are best used as a means to see if you should do further testing or not, typically via OES.
  2. billyO covered the main bit, but I just wanted to point out that the post temper quench definitely is not the problem. Water quenching right out of temper is fine.
  3. I have used Element (Wixom, MI), as well as IMR (Portland, OR). I found that Element has more capabilities, but IMR is cheaper. I have heard that Chicago Spectro is also a good and cheaper source, but have never used them myself. Otherwise, I run samples on OES spectrometers at work. Every job I've had since 2007 had come with access to at least 1 spectrometer, so sending out to labs was just for 3rd part certification, R&D, and calibration purposes.
  4. On the contrary, we know for sure that there is patination going on. We know this because of the dark discoloration. So when we etch something that has Ni in it with ferric chloride, we know that it resists etching since it stays higher than the non-Ni bearing material (not dissolved), and it also resists the patination (also called staining in an etching context) since it stays bright. Patinas are often just oxide layers, with varying thicknesses affecting the color, but they are also often chemical reactions besides oxidation. Many good patinas will rely on a bit of etching to expose fresh metal in order for it to react with the other elements/compounds to form a given patina. I am not familiar with @Jim Kelso's recipes, so cannot comment on them. Perhaps he will chime in. White rust has nothing to do with the iron. It is zinc oxide on a galvanized steel part (or some other element with a white oxide, but not iron).
  5. You'll likely be too hot if you do that. The tin will drastically lower your liquidus temperature. There is nothing wrong chemistry-wise with adding your tin before the copper is molten. You can have a pool of liquid tin that your copper then dissolves into (this is how I did it when I made babbitt). The only real worry with melting the tin first is that you won't know if all of your copper has dissolved in. A working thermocouple and knowledge of your composition and its place on the phase diagram will solve that. For example, if you are using 88% Cu and 12% Sn, your copper will melt at about 1985F while your bronze will have a melt point of about 1560F. I would think you want your pour temp to be around 1700F. If you go with your copper melting point temp you will be nearly 300F too hot. Again, not a non-ferrous expert, so desired pour temp may be a little off. The higher the Sn content, the more severe this problem will be (20% Sn would mean you're 400F too hot!). The biggest problem with the baking soda in the clay is that it greatly lowers the sinter and melt point of the clay. If your clay is turning into a liquid glass, then it isn't able to bond your sand. If it is merely sintering, it is being used up so that you don't have usable clay when reusing the sand (we call this "dead clay", vs "active clay"). Sintering can also lead to difficulties in shakeout and larger sand grain aggregates (which is bad for surface finish when reusing the sand).
  6. You are correct that the baking soda is not good to have in your clay. The playground sand is also not good. Sand blasting sand is going to be a better option if you only have a hardware store to get supplies from. You want to have controlled sand grain sizing to have best results. You want small, but not too small, and a relatively small distribution in sizing, but not too small. For something like this, I would think you want to be in the neighborhood of 35% 100 sieve, 50% 140 sieve, and 15% 200 sieve, though perhaps a little coarser would be better for the permeability. If your copper was truly boiling you would have significant problems. Copper boils at 4,644F. If it is bubbling and merely looks like it is boiling (which is certainly the case here), you have different problems. Most likely oxygen and/or moisture. You'll definitely want to look into the best ways available to you to reduce the oxygen pickup in your melt. Phosphor copper is a pretty cheap deoxidizer (it's a bit expensive per pound, but a little goes a long way). I would also suggest adding the tin before the copper melts. If you get the copper nice and hot, but not quite molten, then add the tin, the tin will melt, then rapidly dissolve the copper into it. You can then be at the right melting temperature and not drastically over. Consult the Cu-Sn phase diagram to look at the right temperature for your composition. I would think 100F over your compositions melt point would be pretty good. You don't want to get too hot, or be hot for too long. I'm a ferrous metallurgist and foundryman, not copper-based. So I may be off a bit.
  7. It is also worth noting that as the billet is folded or cut and stacked then forged down each time, the layers are getting thinner, so the carbon has to travel a smaller distance in later heats. This becomes more of an issue when talking about really low layer billets (such as san mai, for example). It will even come into play when we look at starting materials. If your initial billet is starting with a few chunks of 1/4" material, you'll get slower homogeneity than if you started with more layers of 1/32" material.
  8. For more on temper embrittlement, people should definitely check out the pinned thread on the topic. Alan, I know you read it, you pinned it! I just want to ensure others reading this thread know of its existence. In general, the more I see on the topic, the more I think it is becoming less of a concern. It seems to be an issue with tramp elements (primarily Sb, Sn, P, and As), and good modern steels are clean enough to have it be a very minor issue. Though, not all modern steels are good, so buyer beware. For springs, I'd recommend trying to form bainite, if at all possible. Otherwise, avoid the 500-800F range for tempering martensite, being sure to cool rapidly through that range if you go hotter (e.g. quench it after tempering at 1000F).
  9. @Gary LT I just added a little info to this thread:
  10. This seemed like the best thread to tack this info onto, so it is all in one place.
  11. My understanding is that pretty much any (massively) forward weighted hammer is a dog-head hammer. There are Japanese style dog head hammers, "viking era" dog head hammers, cutler's dog head hammers, saw doctoring dog head hammers, etc. The name seems to have originated from more of the cutler style than the Japanese style, as the profile does look more dog-head-shaped, but it has become the umbrella term for this general type of hammer, with lots of variations on the theme of forward weighted. But I am certainly no expert on it all.
  12. I feel kind of silly not seeing that until you mentioned it, but that is indeed pretty cool.
  13. This really makes me want a wrought/steel faced hammer. Yet another project added to the "some-day" list. Is this not both a dogs head and cutlers hammer? Kind of like the "all toads are frogs, but not frogs are toads" kind of thing. I'm not sure what would make this specifically not a dogs head.
  14. Perhaps @Dave Stephens has some insight based on his experiences with Arctic Fire.
  15. Step one is to not describe things by color alone. What you call orange may be very different from what I call orange, and ambient lighting plays a huge role in perceived color. It is far superior to talk about critical temperature (the temp at which phase change occurs, which varies by alloy) and how much above or below. Heating above critical and allowing to cool in still air is not annealing, it is normalizing. Generally speaking, unless you have a controlled oven, normalizing is going to be a better approach than any makeshift attempt at annealing. Annealing is good for getting as soft as possible by not allowing stresses to occur due to temperature change after relieving all stresses upon heating. These are generally stresses from thermal expansion/contraction, as well as phase changes and recrystallization. The risk is primarily grain growth, but carbide development can also be a serious issue in some alloys. Normalizing relieves stresses like annealing, but, being a faster cooling process, it will cause more stresses upon cooling. These stresses are pretty minimal and you avoid the risk of grain growth and bad carbide development. Grain refinement comes from recrystallization, which (generally) requires stresses to have occurred, then heating above the critical temperature and cooling back down. The key is to not have too many stresses before heating (so you don't develop cracks before you relieve the stresses) and not spending too much time too hot and thus get grain growth, as that is the opposite of grain refinement. Cooling rate below about 900F on normalization cycles is fairly irrelevant as far as grain growth and carbide development go, but there will be some extra stresses induced. These stresses will leave the steel slightly harder, but will aid in more grain refinement in the next thermal cycle (above critical). If you are looking for the best way to get as soft as possible (lowest amount of stress) in a simple forge set-up with simple steels (air hardening alloys and such can be quite a bit trickier), then I suggest a normalize cycle (or two or three), followed by one or two very high tempering cycles (about 1250F, just make sure you don't go over critical). These temper cycles do not need to be very long to have huge benefits in blade geometries.
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