Hi all, I'm trying to learn CI fusion welding for repairs and one-off CI constructions/reproductions.
I'm currently attending a TAFE welding course (Cert IV engineering), and have been hobby welding for 50 years - just want to get rid of bad habits I've accumulated and learn new tricks). The teaching staff there have never learnt CI fusion welding, nor seen it done.....
However, since I'm trusted there, I was able to rummage around the store and found several old packets of cast iron welding rods (made by CIG), dated in the '80s. I also found two unopened tins of cast iron welding flux - with user instructions on the labels.... go figure.
So under the interested and watchful eye of my instructor, I got a few bits of CI out the scrap bin, cleaned them up and went at it.
I heated the pieces up, pretty hot, but not quite glowing. A stip of pine burst into flame on touching the workpiece.
Then heated the end of the rod to dull red and dipped it into the flux (280g Borax/kg - I wonder what the rest is?).
Then I proceeded as if I was putting down a 'normal' bead. It flowed nicely, behaved somewhere between MS welding and bronzing. Seemed too easy, I must admit, given the 'mystery' surrounding CI fusion welding....
After slow cooling and cleaning, the weld looked exactly like the surrounding CI, and appeared completely sound. I haven't cut any on the bandsaw yet to see what the penetration is like, but under the hood I could see both the workpiece and the filler running and mixing nicely in the puddle.

I have a couple of broken CI bench vises to fix and a machine vice with swiss cheese pattern to fill. That's why I want to learn this. I also have a large drill press table with a broken off corner I would like to try restore to original.... the list goes on - broken out T-slots on a milling table etc.

Next try will be the first bench vise and I'll take photos then.

Any experience with this here? Any suggested procedures? Any other advice? No need for me to reinvent the wheel for such an old process....


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