Making Ductile Iron in the Home Foundry

I would try a basic addition rate of one gram per pound to start with and see what you get. Use a control group. Pour one with alloy and one without and do test to each and see if there is any improvement on the one with alloy. Using the in mold you do not have to calculate fade and is easier way to keep control of process. Pouring in stream is fine if you can do it by yourself...hold one crucible while pouring from another...but just an unnecessary step as when you pour into the basin the same thing happens. i will mock up a little drawing of what I mean by the metal disc. and post it when time allows. The disc or the plug will work fine but the disc does not pull any sand loose when it melts and is a cleaner entry into the sprue. The disc do sometimes fail to melt as soon as they should for whatever reason and some melt too soon...the best way to avoid that is to not pour directly on the steel disc and allow the metal to gently cover the disc so it doesn't wash out or float up. I will show that in the drawing.

 

P.S....the amount it takes to stop up the sprue is retardedly high...we were well above ten times the calculated amount as a test. That would normally never be done unless by accident. We still made the castings but had chunks stuck inside the sprue that had not gone into solution.

 

Crude as heck but shows what I mean by two systems...one with straight pour into basin but not on top of alloy just off to the side so it doesnt splash it out......the second is the reaction chamber with alloy in chamber and metal runs through it to homogenize.

 

1 gram of NiMg3 per pound? I assume that was what you were suggesting.

Denis

 

Yes...Im sure you will get some boost from that and may put you where you want to be from the start. Better to over alloy than not enough.

 

I think for a better control I would go with the core instead of thin metal disc. I saw a lot of inconsistencies while using the metal disc. Times for melt through could vary by a couple of seconds and in thin wall we can not have that. I offered to build a pneumatic arm that would lift and set a stopper rod for us here but we were nearly done with the trial. We actually had a university build us a robot to weigh the alloy and set the disc. It worked for about two days and has been in the landfill ever since. I should go see if it has any parts I can use now that I think about it.LOL

 

Thanks for all the info.

By the way, Billy, you may be thinking about various materials to use for a stopper and may have a lot better idea about that I do. However I will say that I used some plain sodium silicate plus sand without any sugar for weakening it and doing so made a stopper that became extremely hard and very durable. I use that on a “mouse trap“ that I published here a while back. The amount of sodium silicate I used was RU sodium silicate diluted with 15% added water. Then I mixed that with sand at 5% of the mixture per weight of sand. I also added propanyl carbonate to act as a kicker for the silicate/sand when it was in its initial mold. If I were making a plug system for what you’re planning to do, I think I would make both the plug and the drain fitting if you will for the sprue out of sodium silicate plus sand kicked off with propanol carbonate before installation. Once the iron hits the silicate/sand it will become granite hard.

FWIW

Denis

 

Here's something:

https://books.google.com/books?id=EeD7e5h9tx4C&pg=PA858&lpg=PA858&dq=ferrocerium+"ductile+iron"&source=bl&ots=Nv0z3s-9QJ&sig=ACfU3U1FaJ57kV11smDWVrYuio9Uwf1xbA&hl=en&sa=X&ved=2ahUKEwjx7Jv0l6nuAhWLCjQIHW0nD9oQ6AEwD3oECA0QAQ#v=onepage&q=ferrocerium "ductile iron"&f=false

Note that a typical ferrocerium alloy has ~ 1% Mg. (No, not much, but home foundry-persons can *get* ferrocerium without buying a huge amount or having an Industrial Connection...)

 

Well, if I get ferrocerium, exactly how do I use it to make ductile or CGI? It has Mg in it alright. I did not see any reports of using it as a primary nodulizer ingredient, but rather as a possible enhancer that has to be used within a narrow range in addition to other primary nodulizers.

Denis

 

I wish I could do iron. I'd try It out myself, then.

Guess: 50 pounds wants between 4 and 8 ounces? Bust up a 6 inch rod, or wire said rod to the graphite stirrer?

 

So I am curious as to whether I can get to iron temps or not with my setup but just was given enough brick to build a new one for cast iron. I may have to try it just for kicks. Someone told me I couldn't get to cast iron temps with it and I didn't really have the desire to until they said that....and now you guys talking about ductile and CGI are making me want to try it just a little more.LOL I would like to make some iron band parts....I may have to try it.

 

I have not posted on this project in a few days. That's not because I've been idle. I think I have a some NiMg3 headed this way that I was able to find. So, I am anxious to try mixing it with some ductile returns that I am pretty sure I can get but have yet to get my hands on.

I am going to have a commercial foundry cast a few (minimum charge involved so may as well get a few made for the same price) levers.

Here are picsof the sand + sea coal +sodium silicate + propanyl carbonate molds. The holes in the cope are there because I did not want to wait a few hours for the propanyl carbonate to kick the Na Silicate and so I gassed it.

The follow board is a scrap of masonite with a very rough cutout of the lever profile. Then I used blobs of Bondo on the back of it to raise it tot he parting line of the lever. Once it was firmly at the right height, I again used Bondo smushed into the gaps between the lever and the board to close up those spaces. A couple coats of glossy paint and a generous coat of Johnson's floor wax and it was ready to go.


The gassed cope. Ten seconds fairly low flow per hole.

I used a 1" spade bit to bore an open riser. The riser may not be truly needed for this part as it is not all that thick. But I will be transporting these molds 60 miles after they are closed. Having the big open riser will allow me to blast compressed air through the closed mold to, just before filling, flush out any bit of sand that could have been jarred loose in closing and transporting the mold. Plus it will make it easy to see the progress of mold filling to avoid over filling.

The spherical recesses in the cope were made by just rotating a fender washer pressed against the sand. It was suprisingly easy to make nicely-shaped recesses to act as molds for the drag location bosses to ensure that the molds would go back together in good register.


The splash basin gates and runners scratched into the drag. (I called the splash basin a "pouring basin" in the video.)
Here is a very rough and ready video I made to show the commercial foundry guy my molds so that he could tell me in advance if he saw any major faults. He says he thnks they should work OK. I will likely not know whether they fill OK until ten days or more from now as I have to take them down when I drop off a few recently poured 26 and 36 inch straight edges next week and will hand him the molds then. Sorry the video is so jumpy at first---I was holding the phone in one hand and the mold in the other. (Walk and chew gum?)



Denis

 

As someone who "officially" has difficulty "walking and chewing gum at the same time," this Vid looks fine.

 

Hope it all goes well Denis.

Is ductile iron the same as nodular cast-iron?

Cheers Charlie

 

Yes, why have a single name for something when you can confuse the general public with several names?
From Wiki
"Ductile iron, also known as ductile cast iron, nodular cast iron, spheroidal graphite iron, spheroidal graphite cast iron[1] and SG iron, is a type of graphite-rich cast iron discovered in 1943 by Keith Millis.[2] While most varieties of cast iron are weak in tension and brittle, ductile iron has much more impact and fatigue resistance, due to its nodular graphite inclusions.

On October 25, 1949, Keith Dwight Millis, Albert Paul Gagnebin and Norman Boden Pilling received US patent 2,485,760 on a cast ferrous alloy for ductile iron production via magnesium treatment.[3] Augustus F. Meehan was awarded a patent in January 1931 for inoculating iron with calcium silicide to produce ductile iron subsequently licensed as Meehanite, still produced in 2017."

Denis

 

Ah ha!
Some months back, someone on here posted a link to Youtube I think, which showed an Australian foundry making Nodular cast-iron. From memory it was explained that graphite can be placed in the pouring basin, or sprinkled inside the mould before pouring.

You may recall it Denis,

Cheers Charlie

 

The thing is I think it is necessary to use use a nodularizer (there are a few varieties with NiMg3 the most talked about) in a pot of iron that is low in sulfur and high in carbon. Carbon alone won't do it. At least that is what I have gleaned so far. There seems to be not a lot of specific information on exact amounts of nodulizer needed nor am I aware of anyone making ductile in the small foundry setting. Likely folks have done it. But finding them and their methods is elusive.

If you know of an Aussie who has done it, please post cuz I'm anxious to read about it.

Denis

 

Charlie Do you remember that youtube link about a Australian foundry making ductile iron?

 

Sadly I don't.
I searched on Youtube and couldn't find it; I may have bookmarked it on my other computer 200km away.

I do remember that someone on here posted the link; it was a training film the sort shown to high-school students or perhaps apprentices,

Cheers Charlie