Casting aluminum bronze C95400

Discussion in 'Sand Casting' started by Tobho Mott, Aug 29, 2017.

  1. Tobho Mott

    Tobho Mott Gold Banner Member

    Aluminum bronze:

    Alloy C95400:
    Cu% 83
    Fe% 3-5
    Ni% 1.5
    Al%
    10-11.5
    Mn% 0.5


    This is an interesting alloy. It is tough as nails, so I have used it to make a couple of bronze axes.

    The first one was a bit more fantasy themed, but it still worked for chopping wood, so it is at least functional. I made the pattern to have a rear-facing bit that ended up being almost entirely useless. I ended up selling it to a friend for only a little more than I paid for the materials so I could afford to make a better one for myself, and he says he is getting good use out of it clearing brush etc., on his farm.

    IMG_20170326_190853328_zpsr9cm6l1k.jpg

    And here is the new one, I did more (as in, any at all) research on the proper shapes and angles of proper axes while keeping some of the design aspects of the first one. I can't wait to chop down the dead wasp-infested tree in my front yard with it to see how it performs! Got some work to do on it first though obviously. I'm also planning on taking it camping with me in late September, then it'll get a good workout chopping hickory logs for our all night giant bonfires!

    IMG_20170827_140355489_HDR_small.jpg

    Magnets will stick to it, and it can be hardened by heat treatment, though I have not figured out how to do that part yet; I have done work hardening instead. Without knowing much about how to do that either...

    Notoriously tempermental to cast, as it really wants to turn into dross. Here is some info I found online about casting it successfully:

    https://maritime.org/doc/foundry/part4.htm:

    "Aluminum bronze alloys are difficult to cast in green sand molds because of the high drossing tendency of the alloys and the possibility of surface pinholes and porosity in the finished castings. The defects caused by high moisture in the green sand molds can be minimized by using dry sand molds. It is recommended that dry sand molds be used."

    Dry sand molds was a new one on me, so I looked a little deeper...

    http://maritime.org/doc/foundry/part2.htm:

    "Dry-sand molds, as the name implies, are molds made with tempered sand and then thoroughly dried by baking. Dry-sand molds are used when a mold of high strength is needed, or when low moisture content is important. Dry-sand molds are not recommended for complicated castings unless special care is taken to obtain sand mixtures which will give good collapsibility, so as to prevent hot cracks or tears."

    I did not do that, I guess that explains the surface pinholes and what may be a slight hot tear in the eye of the latest casting...

    I also just received a copy of C.W. Ammen's Casting Brass in the mail. It has some great info on how to (profitably) cast various alloys of copper including a section on aluminum bronze which I have not had time to go over yet. If I find more there, I'll ty and add some info to this thread.

    Here is the advice I got from a member of alloyavenue about casting aluminum bronze, which I actually did try to follow:

    YouTuber Olfoundryman has a explained in some of his videos how using a skinny tapered sprue located at one end of an egg-shaped pouring basin reduces turbulence and prevents whirlpooling during the pour that could suck air into the mold cavity, so that has been my approach. Pouring speed is important, you don't want to overflow the pouring basin by pouring too hard or let the sprue drain out during the pour by going too slow, but this applies to any casting.

    I also tried to at least make an effort to make proper gating in terms of using an extended runner and keeping the cross sectional area ratios of sprue base to runner to gating at roughly 1:4:4 (without getting too anal about a half-millimeter here or there), per my memory of the Navy Foundry Manual, linked elsewhere on this site.

    I think I should have added some cereal additive to my core to improve collapsibility, as the core was tough to break out, maybe this would have meant avoiding that (possible) hot crack in the eye. I think that is not bad enough that I have to scrap the casting, as it is only going to be for my own use.

    The dry sand mold may have prevented the slight pitting I got on the surface as mentioned. I had a small amount of that on the first axe I cast too.

    Anyhow, here's the video! I tried to make it fun and let my inner A Song of Ice and Fire (AKA Game of Thrones) nerd come out a little more than usual in the intro, since these axes are in part inspired by the ancient people of George R. R. Martin's amazing fantasy world. But don't let that scare you off...



    And here's just the money shot, for those who are always in a rush to get to the good part:

    [​IMG]

    There's another post (with video) here explaining how I made the core that I used in this casting: http://forums.thehomefoundry.org/index.php?threads/quick-n-dirty-cores-for-the-backyard-foundry.8/

    One thing not mentioned in the video is that I used a charcoal cover on the melt. I figured if it is really so prone to oxidizing, I might as well put something in the crucible that hopefully loves to eat up oxygen even more. Seemed to work, but I don't know if it will agree with whatever is in the Casting Brass book, we'll see when I get a chance to sit down and read it a bit.

    Anyone else here have any secret lore to share about casting aluminum bronze? I'd love to hear it, especially if you have tried those dry sand molds or done the heat treatment! Any instructional type advice or links about work hardening it would also be of interest, at least to me...

    Jeff
     
    Last edited: Jun 6, 2018
    OCD likes this.
  2. PatJ

    PatJ Silver

    Nice info.
    It will take me a while to go through it all though.
    I may have questions after I read/view it all.
     
  3. Tobho Mott

    Tobho Mott Gold Banner Member

    I've got a few questions myself, but I have dug up a few nuggets of info I'm happy to share. Most of it is above and in the video, but if you ask here and I don't know, maybe someone else will and we can all learn something!

    Jeff
     
  4. DavidF

    DavidF Administrator Staff Member Banner Member

    Man that came out nice :)

    have you considered cutting a Celtic or tribal design into the pattern?
     
  5. Tobho Mott

    Tobho Mott Gold Banner Member

    Thanks! Yes, I have been thinking I might be able to make some interchangable symbols, runes, etc., that could be stuck on, removed, swapped out.

    I did not want to try carving anything into the plain axe pattern I'd made once I finally got it to its current state where I can live with its existing imperfections...

    I've also thought about casting an aluminum handle directly into the eye, but I am going to go with the hickory log I saved from the campsite where I first got hooked on this whole playing with molten metal thing a few years ago instead. :)

    Jeff
     
  6. cae2100

    cae2100 Lead

    I was thinking about it, and it's really wierd how aluminum bronze is magnetic. I wonder if it's due to the very tiny amount of iron in it? With that small of percentage, I dont think it would contribute to it's magnetic nature.
     
  7. OCD

    OCD Silver

    That's exactly why it's magnetic in nature, iron content.
    But it make's a more durable metal also, especially for a axe head.

    Nice job Jeff.
    Now you'r ready for WAR. lol
     
  8. Tobho Mott

    Tobho Mott Gold Banner Member

    Makes sense, it has 3-5% Fe, so I assume that is why also. If it's not that, I guess it's JFM. I weighed the blade last night, it's almost exactly 700g or ~1 lb 8-1/2 oz (before doing any grinding). So, more of a hatchet, I guess. Still ought to be pretty good for chopping down psychic demon-trees and whatnot...

    Jeff
     
  9. Tobho Mott

    Tobho Mott Gold Banner Member

    Ammen's brass casting book does go over heat treating aluminum bronze, but the closest ally to C954 I saw described there says it does not respond, which disagrees with several other sources I've checked. A mystery for a other day I guess, I don't have a heat treating oven anyhow.

    Got the new axe pretty much finished - cold working the edge, grinding and polishing, making a handle and installing the blade on it. All in all I'm very happy with it, not planning on peening the whole blade this time, I like the shiny look! Still going to sharpen it a little more, but I think it'll cut well in it's current state.

    image001.jpg

    IMG_20170907_054706102.jpg

    I got some more video of fiishing it up and plan on shooting some of the field testing I I plan on doing: at a minimum that all still needs editing and uploading, but it's not so much related to casting so I may not post it here. Not sure how much value there would be of posting video of me fumbling along figuring it out as I go, other than the "if he can do it so can I" factor... :)

    Jeff
     
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  10. OCD

    OCD Silver

    Not shiny enough Jeff.

    400, 600, 800, 1000, 1200, 1500, 3000 grit, then compound, buff & polish. :D

    Outstanding Yob
     
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  11. DavidF

    DavidF Administrator Staff Member Banner Member

    I like the brushed finish, going too shiny will take away from the over all looks IMHO...
     
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  12. Tobho Mott

    Tobho Mott Gold Banner Member

    Well I got to 600 anyhow... Was not going for a brushed finish, that was just the highest grit I had on hand.

    Jeff
     
    Last edited: Sep 7, 2017
  13. Robert

    Robert Silver

    That's beautiful!
    R
     
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  14. Tobho Mott

    Tobho Mott Gold Banner Member

    :) Thanks!

    I posted it on AA too, someone thought the handle looked too big. Now I am wondering if I should thin it down more... Already planning on trimming the length but was originally only planning on taking off maybe an inch at most.

    I wasn't sure if they meant too thick or too long (or both). I'm not sure if it was maybe just an illusion of perspective if they meant too long... Here's a pic of the axe from a different angle, I'd appreciate any thoughts about the size (both length and thickness) of the handle, if you guys have any opinions about that...

    Jeff

    axe2.jpg
     
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  15. OCD

    OCD Silver

    Only true way to find out is chuck it at a tree and see what it does.

    Did you pound a wedge in the top of the handle to keep the head from flying off?
     
  16. Tobho Mott

    Tobho Mott Gold Banner Member

    Heh, I finally heard back - saw the same suggestion in my AA thread...

    Wedge: check.
    Test run: when I get home after work today!

    Thanks,

    Jeff
     
  17. DavidF

    DavidF Administrator Staff Member Banner Member

    Take a video of the first toss :)
     
  18. Tobho Mott

    Tobho Mott Gold Banner Member

    Only way you'll ever be sure if it's really the first toss, is if it doesn't stick in! :)

    I am already planning on uploading another video (or two) about the axe build, and the plan is definitely to include some chopping and throwing action shots at the end. The tricky part is that I already have over 3h of footage of the grinding, peening, sanding, handle-making, and handle-installing that needs to be ruthlessly edited down to one (maybe more likely two) 15-20 minute video(s)... I could go long form like Jason's awesome wax dogs videos, but even with a personal interest in the outcome I have yet to find time to watch any of those in one sitting...

    I will probably just drop most of the handle-making footage and a lot of the grinding; it's pretty boring to watch, and it's not like anyone is going to learn anything useful by watching me trying to figure out how to do all that as I go using the wrong tools for the job at 20X speed anyhow! :)

    Jeff
     
  19. crazybillybob

    crazybillybob Silver Banner Member

    The only "wrong tools" for the job are the ones you haven't tired yet ;) If they worked they were the right tools!! A belt sander in a bench vise works much better at sharping an ax than that fancy belt grinder in the catalog on you desktop. (one you have in front of you...the other is only in your dreams :D)

    Nice Ax!
     
  20. Tobho Mott

    Tobho Mott Gold Banner Member

    Thanks CBB, you make a good point!

    Jeff
     

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