Announcement

Collapse
No announcement yet.

Welding cast iron

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Given all the risks etc. I'd be more inclined to get a specialist in "metal stitching" to do it:

    http://www.google.com.au/#hl=en&rlz=...w=1920&bih=785

    Comment


    • #17
      Originally posted by Carld
      Apparently he was only heating the cast iron enough to get the copper to rub onto the cast iron.
      Think about that Carl. If you rub on a piece of cast iron with a brazing rod, what are you going to accomplish?

      You have to get the copper hot enough to melt. Thats HOT.
      "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

      Comment


      • #18
        Originally posted by Carld
        Well, this didn't get any traction in the welding forum so I will try it here.

        Has anyone tried this method of welding cast iron and did it work?

        http://gasengine.farmcollector.com/I...m_medium=email
        The necessary question before starting is that while trying it in a HSM shop - or where-ever - can you afford to lose it if it doesn't work out as well as you'd hoped for - or at all?

        Comment


        • #19
          Rubbing the copper on half hot CI sounds to be about the same as the black smith brushing iron as it cools with a brass brush to put a brass finish on it. You brush iron or steel as it cools at a black hot not red. If you brass brush it to hot the brass burns off. I can see how you could tin CI with a layer of copper on it. I will put that in my bag of tricks. Thanks for the tip.

          Fred P..............

          Comment


          • #20
            Originally posted by lazlo
            Think about that Carl. If you rub on a piece of cast iron with a brazing rod, what are you going to accomplish?

            You have to get the copper hot enough to melt. Thats HOT.

            No ... that's what everyone here is trying to tell you Robert. The process described is a method of tinning by which a very tiny layer of copper atoms is adsorbed onto the surface. After this tinning is accomplished, he uses a soft solder to fill the crack. This is not brazing or welding but a method of soft soldering a leaky crack - not a structural joint.

            Comment


            • #21
              Originally posted by Fred P
              Rubbing the copper on half hot CI sounds to be about the same as the black smith brushing iron as it cools with a brass brush to put a brass finish on it. You brush iron or steel as it cools at a black hot not red. If you brass brush it to hot the brass burns off. I can see how you could tin CI with a layer of copper on it. I will put that in my bag of tricks. Thanks for the tip.

              Fred P..............

              AH-HA! Thanks Fred. I knew there was a similar process I had heard about but I couldn't place it. My fiance's father is a blacksmith and farrier. He was telling my about this about a year ago. I thought he was referring to oxidization colors - that bronze like color you can achieve by tempering a shiny piece of metal. Then I saw an ornamental piece that had been brushed with a brass brush and what he was talking about became obvious.

              Comment


              • #22
                Originally posted by Fasttrack
                No ... that's what everyone here is trying to tell you Robert. The process described is a method of tinning by which a very tiny layer of copper atoms is adsorbed onto the surface.
                Tom, explain to me the mechanism of material transfer.

                Brass has a considerably lower melting point than copper, which is why, when you brush hot steel with a brass brush, it melts the brush, and coats the metal. I've done that as well. If you do the same thing with a copper brush or scrubbing pad, the base metal would have to be considerably hotter.

                A lot of blacksmith shops use copper or bronze brushes to clean-off the firescale so you don't leave deep scratches in the final piece. That doesn't coat the workpiece unless it's blazing hot, and the shop smith gets mad at you for melting his expensive copper brush...

                I'll try it over the weekend with mild steel and some refrigerator coil. I'll bet a cold beer the base metal has to be close to the liquidus of copper, which for thin copper tubing and a heavy (high thermal mass) workpiece is probably a red heat.
                Last edited by lazlo; 03-30-2012, 02:43 AM.
                "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                Comment


                • #23
                  Originally posted by lazlo
                  Tom, explain to me the mechanism of material transfer.

                  Brass has a considerably lower melting point than copper, which is why, when you brush hot steel with a brass brush, it melts the brush, and coats the metal. I've done that as well. If you do the same thing with a copper brush or scrubbing pad, the base metal would have to be considerably hotter.

                  A lot of blacksmith shops use copper or bronze brushes to clean-off the firescale so you don't leave deep scratches in the final piece. That doesn't coat the workpiece unless it's blazing hot, and the shop smith gets mad at you for melting his expensive copper brush...

                  I'll try it over the weekend with mild steel and some refrigerator coil. I'll bet a cold beer the base metal has to be close to the liquidus of copper, which for thin copper tubing and a heavy (high thermal mass) workpiece is probably a red heat.
                  Fair enough. I'll try it with cast iron instead of mild steel.

                  Comment


                  • #24
                    Originally posted by Fasttrack
                    Fair enough. I'll try it with cast iron instead of mild steel.
                    I'm not arguing Tom, I just don't understand how the transfer of copper to the base material would happen, unless you're effectively brazing (melting the donor material).

                    I didn't offer to try the experiment on cast iron, 'cause I don't have any cast iron I'm willing to submit to the cause
                    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                    Comment


                    • #25
                      Originally posted by lazlo
                      I'm not arguing Tom, I just don't understand how the transfer of copper to the base material would happen, unless you're effectively brazing (melting the donor material).

                      I didn't offer to try the experiment on cast iron, 'cause I don't have any cast iron I'm willing to submit to the cause

                      I just smashed up and removed a 320 lb cast iron bathtub. I've got plenty for the cause


                      I could slap together a BS argument regarding the material transfer, but I simply don't know enough about it to offer a solid explanation. We'll just have to try it and see ... I'm an experimentalist, not a theorist after all.

                      Comment


                      • #26
                        I'll hazard a half arsed guess. Could you possible have solid-solid diffusion as a transfer mechanism. I remember solid-solid diffusion being mentioned in my materials science class many years ago but I don't remember the exact circumstances. It seems like solid-solid diffusion occurred at something below the melting point. I want to say that one material in the diffusion couple was copper but I don't remember what the others were.

                        Comment


                        • #27
                          Originally posted by ckelloug
                          I'll hazard a half arsed guess. Could you possible have solid-solid diffusion as a transfer mechanism. I remember solid-solid diffusion being mentioned in my materials science class many years ago but I don't remember the exact circumstances. It seems like solid-solid diffusion occurred at something below the melting point. I want to say that one material in the diffusion couple was copper but I don't remember what the others were.

                          That was going to be my guess, but I couldn't find the info I wanted on Google, although I did find that [email protected]@ book that described "cold soldering".

                          Comment


                          • #28
                            Originally posted by ckelloug
                            I'll hazard a half arsed guess. Could you possible have solid-solid diffusion as a transfer mechanism. I remember solid-solid diffusion being mentioned in my materials science class many years ago but I don't remember the exact circumstances. It seems like solid-solid diffusion occurred at something below the melting point. I want to say that one material in the diffusion couple was copper but I don't remember what the others were.
                            That was my (also half-arsed) guess.

                            I do seem to recall that gold is particularly diffusible, so much so
                            that in the big government gold vaults, they allegedly do not
                            store the gold ingots on metal shelves as the gold would diffuse into
                            the shelf and be lost. I want to say that I recall that they use
                            wooden pallets so that periodically they can burn
                            the pallet and recover the gold that gets diffused into it -- but
                            this sounds a bit too weird :-/

                            Frank

                            Comment


                            • #29
                              Originally posted by ckelloug
                              I'll hazard a half arsed guess. Could you possible have solid-solid diffusion as a transfer mechanism. I remember solid-solid diffusion being mentioned in my materials science class many years ago but I don't remember the exact circumstances. It seems like solid-solid diffusion occurred at something below the melting point. I want to say that one material in the diffusion couple was copper but I don't remember what the others were.
                              Cameron:

                              The clasic example is copper and zinc solid solution of brass at the interface.

                              I would be more inclined to just plate copper into the surface of the crack in the cast iron using a copper sulfate solution.

                              -bob

                              Comment


                              • #30
                                My guess is you dont even need the heat. Just rub the crack with the copper tube and the crack will turn copper colored. Then fill with solder. The copper gives the solder something to stick to better than just plain old cast iron.
                                Every Mans Work Is A Portrait of Him Self
                                http://sites.google.com/site/machinistsite/TWO-BUDDIES
                                http://s178.photobucket.com/user/lan...?sort=3&page=1

                                Comment

                                Working...
                                X