Casting a Shackle, My First Try at Iron

Interesting, if I could make ductile iron.

 

Magnesium is not usually added as pure magnesium though it can evidently be done that way with special gunning equipment.


From http://www.phase-trans.msm.cam.ac.uk/2001/adi/cast.iron.html:

The magnesium is frequently added as an alloy with iron and silicon (Fe-Si-Mg) rather than as pure magnesium.

Direct addition of magnesium in the home foundry situation would be exciting. However, I do have a couple pounds Fe-Si-Mg in soybean size chunks that my foundry-owner mentor gave me 6 months ago should I wish to add some to my melt. I have not tried that yet. But, it could be tempting just to see how ductile one could make the iron. How much is lost in melt/remelt I don't know. Does anyone have data on that? I think I saw a paper a few months ago that indicated both Si and Mg were decreased in a given melt but I think the losses were on the order of 20%. Not at all confident in that number though.

Denis

 

Jammer gave me some of what I think he said was ferromagnesium last year, and my intent was to add it to the iron when I pour engine crankshafts.
Not sure if it will work or not, but I have seen it for sale at some of the supply places.
We may have to order in bulk and then split it among ourselves, assuming that it worked.

.

 

I think we’d need to have a sit-down with a metallurgist to determine practicality of making backyard ductile. Might be more to it than Mg.

Denis

 

What I keep reading is that Mg only works for a few minutes, so folks add it just before pouring. After that, it’s still part of the alloy, it just doesn't help make the iron ductile anymore. So even if you start with ductile iron, the Internet claims more magnesium is needed before pouring.

 

Yes, putting the pattern back in after dusting the mold cavity. I forego this if I think that it will cause damage when I have a complex pattern. There is a fine line between enough and too much, but a little puff with the bellows clears the pattern for another go. The finer the better. That is why I use the locksmith grade.

 

This is a paper a metalurgists sent me a few years ago. I had given some Nickle-Mag3 to Pat and a couple other guys. Maybe enough for a 10 pound pour.

For making the ductile iron at home there are a number of ways you could do it. Let me think on that and suggest some. We use two processes at Cast-Fab. Most of the iron is made using the tundish process. In this process we have special ladles which are covered, they are like a vessel of sorts. The alloy is dropped into the opening in the top, and contains magnesium ferrosilicon, an inoculant, and cover steel, and the hot metal is tapped into the hole. We fill it very quickly, about 100 pounds per second. Most treatments are 5,000 to 8,000. In the small foundry we use another converter called the Sigmat process. The vessel is a flow through type where the iron is poured in one end and travels horizontally to flow over the magnesium ferrosilicon and out the other end to be captured in the pouring basin. We discontinued another process several years ago called the open ladle treatment, and at other foundries I have used the Gazal process and the sandwich process. The open ladle treatment uses a Nickel-Magnesium alloy. It is pretty simple – you make your base iron, then after skimming the ladle and setting it on the floor, the Nickel magnesium alloy is dropped (actually slid in over the side) into the ladle where it sinks to the bottom. As it dissolves the magnesium is released. There are two alloys made by INCO for that which I have seen used: Alloy #3LC and Alloy #4. 3LC is almost pure nickel and is highly efficient. About 80 to 90% of the magnesium is recovered. #4 is only about 57% Nickel, with the rest iron (except for the magnesium). It is claimed to be by INCO as efficient but in practice it is not. We still use #4 alloy as trim additions. Both alloys contain about 5% Magnesium. Therefore since ductile iron runs say 0.035% to 0.045% Magnesium, to treat 30 pounds you would need only about a quarter pound. After treating you would need to inoculate which you could do with the ferrosilicon and do an in stream inoculation. It could be put into the sprue.

http://www.millerandco.com/products/inco/incomag_alloy3lc.html http://www.millerandco.com/products/inco/incomag_alloy4.html

I’m assuming you don’t want to go the route of the second vessel (tundish or Sigmat) which would be awkward for a smaller batch size. I’m also going to see what I can find out about the in mold process for you. We used it in a test at the first foundry I worked at in 1976 but I don’t have any experience with it. The sandwich method also involves a second ladle. I will check to see if I have any Incomag #3LC. I know I have Incomag #4. If you want to try that method I will send you a piglet, they are about 2-1/2 pounds. You would have to cut it into the smaller pieces. For PPE you would want the obvious equipment for handling the molten metal, plus the magnesium reaction is quite bright, like flashbulbs going off, for seconds to minutes. You would need tinted glasses. There is some magnesium smoke that comes off. I would suggest doing it in either an open area or have a good ventilation. The base iron needs to have a low sulfur content. Can you check your base iron chemistry with a test heat? The magnesium may addition can be adjusted to handle some sulfur levels that are high as magnesium and sulfur readily combine, but then you will have a little more slag and dross.

 

In a way the idea that Mg loses its ductile-inducing quality after time seems surprising. But the same phenomenon timing-wise occurs with Silicon. For it to reduce the tendency of iron to become hard, it has to be added to the melt just a few minutes prior to pouring. So I am not terribly surprised that it loses its ductility-inducing properties with time.

Since sulfur in the melt should be at low percentages according to the useful info posted by Jammer above, and since the content of sulfur of iron scrap will not be known to us ordinarily, perhaps starting with known ductile iron scrap (pipe?) would help reduce the chance that the melt would have excess sulfur. Just throwing the idea out there fwiw.

Denis

 

There was a small ear off the runner of the shackle casting which I broke off to look for white iron.

 

Interesting video trailer. He hit every essential point that we’ve come up with so far in this thread covering it all and what was his trailer two or three minutes long.

Denis