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patrick

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Everything posted by patrick

  1. patrick

    metallurgy

    Thomas, thanks for the good words. Please feel free to give them my email. I am looking for interns. Will you make it to quad state this weekend? We're heading there tomorrow.
  2. patrick

    metallurgy

    For you The Complete Modern Blacksmith by Alexander Weygers will be a good investment. He covers lots of ways to recycle old steel into tools and does so based in their prior use rather than knowing the specific steel grade. Practical Blacksmithing is another good reference. Almost everything you need can be made from low carbon/low alloy steel. The exception, and even here it is not an absolute necessity, is hammers. Other steels often offer significant advantages but require that deeper knowledge not only of alloying elements but also heat treatment if you are going to use them. Grade 1045 is perfectly fine for hammers, but others will work too. That one is cheap and easy to heat treat.
  3. The easiest way to see big crystals id to find a galvanized item: trash can, highway gaurd rail, ductwork for a central heating system etc. I've seen grains much larger than 1/4 inch on all these things. Not every galvanized item will show these big grains but many do. The other place you can often see grains without the need for a microscope is old brass door hardware. The are often castings with fairly large grains. Over time the action of people grabbing the door handles will have an etching effect making the grains visible. When i was in college one of the examples Dr. MOBLEY used was those turbine blades Frosty mentioned. He had a set of 3 that were all the same part. One was made with small equiaxed grains. The next best had larger directionally solidified grains and the 3rd was a single crystal.
  4. It seems that metallurgists have done a disservice to the rest of the wolrd by using the word "grain" in so many different ways. That is clearly making it hard for everyone to understand each other and the various resources everyone has reviewed in the past. It also doesnt help that there are so many different metals. Some share behaviors and others have unique characteristics yet we tend to use the same terms all around. Also, many of the technical references are written from the theoretical view assuming thermodynamic equilibrium, which we rarely have in real life. I will try to address the questions i see being raised here but it is going to take a little while to bring all those thoughts together.
  5. A slip plane occurs within a single crystal and is the preferred plane on which the atoms in that crystal will slide past each other. The experiment you did was not showing you slip planes in the metallurgical sense as that would only be visible with a microscope. What you were seeing was the effect of friction between the hammer and work. There is friction at the contact surface over the entire area of contact. This frictional effect penetrates into the work in a pyramid shape. Assuming top and bottom dies of the same size and contact area you will have 2 pyramids pointing at each other. The height of the pyramids is a funtion of the contact area on the surface. If your blow is hard ebough you can get the two pyramids to intersect along the center of the workpiece. If you dont or cant hit hard enough then they will not collide at the center. If this collision does not happen you will always end up with the fish mouth defect no matter how hit or cild the work is.
  6. Bob, you can use the same canvas/rubber belting for the strap that is used for the drive belt. You nee two keys for each die. The are positioned on each side of the die in opposite directions. Taper is 1/8 inch per foot. The dovetail angle on my Bradleys is 5 degrees. Since this is a 2 wedge system you do not have a compound angle. Send me a pm if you have more questions. Id be happy to discuss details on the phone. Patrick
  7. I found the source finally. It comes from some Chambursburg literature on their self contained hammers. There is a table which shows that a 5000 lb hammer can work 10 inch square alloy steel on a production basis.
  8. Guys- I recall reading quite a long time ago that for efficient industrial forging a hammer should have 50 # of ram weight for every 1 square inch of cross section. Does anyone else recall this recommendation and where it came from? If I had to guess I'd say old Chambersburg literature but it could have been in an old book.
  9. Cooling rate determines the as quenched microstructure which in term strongly influences the stresses generated. Agition can increase or decrease cooling rate depending on how agressive it is. The are many other factors that influence quench related cracking such as part geometry so you really have to consider them all together if you are trying to prevent cracks.
  10. As i mentioned it can improve corrosion resistance, machinability and to some degree hardenability. It does indeed segregate to grain boundaries leading to hot shortness, but if the phosphorus content is not too high you could see those benefits. 12L14 is an example af a free machining grade that has both phosphorus and lead as Intentional additions to improve machinability. Most steels used in engineering applications consider it to be an impurity so there are not many examples of its use in modern steel making. Even in the historical context it was there not added on purpose but was a carryover from the ore or fuel.
  11. In wrought iron phosphorus can provide some corrosion resistance. In some low alloy steels it is added to aid machinability but those are exceptions. In bloomery iron making it would most likely have been an impurity in the ore or maybe in the coal if mineral coal was used for fuel. Today it is an Intentional addition to liquid steel during steel making.
  12. I dont recall the motor pully size for you machine. Mine are 8 inch. I know of another smaller Bradley that was set up with a jack shaft a d uses a pulley in the 20 to 30 inch diameter. This set up is more loke what would have been used if the hammer were connected to a line shaft. This large shaft pulley has the advantage of giving you nearly instant single blows which is tough to do with the small pullys.
  13. I can't think of anything specific you would need to arrange with a forging company that would be different than with any other company. You need to know exactly what you want them to produce and you need to clearly communicate your expectations. You need to clearly understand the needs of your customers, including industry and customer expectations. These are all things you'd have to do with any company though. Patrick
  14. Case hardening or case carburizing where carbon is added to the surface of an item through diffusion processes can have widely varying depths depending on the time and temperature used. In industrial practice I have seen things like rail road bearings with effective case depths of 0.100 inches. Another method of increasing surface hardness is to expose the item to a high nitrogen environment. Usually that is done with steels having about 1% aluminum. The aluminum reacts with the nitrogen to form a uniform aluminum nitride coating. This coating is generally only about 0.010 inches thick but can have a hardness of about HRC 70. Intentionally adding alloying elements to just the surface of steel is generally not done because it is not practical. If you attempted to melt just the surface to allow alloying elements to get into the steel you'd be left with an as-cast structure on the steel surface which may not be be what you want, especially if you have already forged the part. If you will forge after alloying addition is made, that likely will be lost due to oxidation. If you attempt to add alloying elements via diffusion processes as with carburizing, you will be there a very long time. That is because the alloying elements in question have fairly large atomic radii and very slow diffusion rates in iron. Only those elements with very small atomic radii, such as carbon and nitrogen, are suitable for difussion based surface alloying.
  15. I run a 300 and a 500 Bradley guided helve both using the canvas rubber belts already mentioned. I am using the 8 inch diameter motor pulleys recommend by Bradley and i don't have any issues with belts heating. You need to have the belt tight enough without any load that it will stay in motion but not grab the drive pulley. Others, i turn the motor off between heats to avoid getting a hot spot in the belt. I do find that extra tacky belts can be helpful so i apply honey when needed. If they are too tacky dust with baby powder.
  16. Wow that was a long time ago, Thomas, probably 18 yrs because i was still living in ohio when i got those bars.
  17. I was able to do a quick review of all my posts and found several that are promising. Thanks for that tip Irondragon. Thomas-I forgot to ask you what kind and size of hammers you got? Will you keep them all and set up a school? You are a fantastic teacher! Patrick
  18. Thanks guys. Thomas-Things are going well and life is full. I got the 500 lb bradley running last fall. At the moment most of my time is going into building a shop for Josiah. Annabelle is wrapping up her senior year and work is full of fun projects including some new interns starting an just over a week. I've been asked to consult on the metallurgy portion of a new book on knifemaking which is why I was looking for my old posts. Many of the errors I see in the manuscript I addressed in those old posts. The bulk if the book is very well done and I find it very enjoyable to read so I think with some tuning on the metallurgy side it will be a very good resource.
  19. Hi all. I'm looking for posts I put up years ago on various aspects of heat treatment. I've been using the search tools on IFI and have been able to locate a few, but I haven't been able to figure out how to search for all my post on a given forum without including a search term. Is there a way I can do that? I recall that years ago I put up some info on Keenjunk and I recall some folks saving that and reposting it here. Does anyone have that material they could share with me? I'd like to use it for a project I'm involved in and though I could sit down and rewrite it, it would be much easier if I could use what I've already generated. thanks. Patrick
  20. I run Bradley's too but mine are guided helve. I have a lot of literature on the Bradley hammers and would be happy to help. In your first video it looks like you might have the dies a little too close. There should be a gap of a couple inches between them when the hammer is at the bottom of the stroke. This allows the linkage and cushions to flex when the hammer is running. With that flex the dies should just touch.
  21. I wonder who that was. I had a professor and lad assistant who were both former Battle guys.
  22. Yeah carbon content s that high usually are not carburized. Those grade usually are limited to 0.3 carbon. Higher carbon in the base material has less driving forced to absorb more carbon. Also by keeping carbon low in the base material you get better core toughness.
  23. Given the alloy it is most likely induction hardened. It can be annealed as Thomas noted but you don' have to worry about scaling away the high carbon layer because the carbon content will be fairly uniform throughout the pieces.
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