nodular iron from recreational foundries?

AFAIK (from reading, not doing), nodular iron is produced by heat treating regular cast iron -- you hold it above the transition temperature for a good long time to give the carbon time to come out of solution.

But it was an old book, so they may do something different now.

That makes malleable iron; I believe it's a day or two anneal up around

2000°F.

Ductile iron is produced by innoculation with cerium or, more commonly, magnesium. Magnesium has a boiling point far below the pouring temp of iron, so it is usually added as an alloy with nickel or possibly copper (5% Mg copper would be easy enough to produce at home, and the

Your best results will be to try to convert gray iron to ductile. In order to do that, assuming you use a cupola for melting your iron, you must lower the sulfur content, then inoculate with ferrosilicon and a product called Glomag, each of which can be obtained from either a foundry supply, or an iron foundry. Temperature control and the ability to handle molten iron are important. You're not likely to enjoy much success if you intend to melt in a crucible furnace.

If you're interested, I can provide a flow sheet for preparing 100 lbs of ductile iron from scrap steel. Contact me on the side if you're interested. The information came from a commercial iron foundry (a trusted friend) that does exactly that. I've yet to try it, but I will in the future. I'll melt with an induction furnace.

Harold

While you're at it, mention to Adam that Meehanite is not a grade or type of iron. It's a tradename for a patented casting process. It happens that the process uses Meehanite-specified iron formulations, but there are several different ones, and I don't believe they are necessarily nodular.

-- Ed Huntress

Thanks to all for the responses, all of which where exactly the kind of information that I'm looking for. I found several Nickel Mag products on the inco website, but I have no idea if they will sell it in sub ton quantities. ( I used to know some folks at inco, but that was a long time ago and they were pretty old, so it'll have to be a cold call and ask for a sales rep. Still you never know.)

I was aware that Meehanite referred to a proprietory process, rather than a particular iron structure: that was actually part of what I was trying to get to: methods of producing iron of controlled structure and composition that are available to the small foundry. The Meehanite registered foundries are definitely producing flake iron as well as nodular using the process. Ed are you sure that Meehanite is patented? I was of the impression that it is a trade secret. If it is patented the base patents will have long since run out since the initial work dates back to the '20s. Can you point me at patents? I'd love to read them if you know any.

Once again, thanks to all. Any additional responses also appreciated. Harold, I will be contacting you offline, it sounds like you have information that will be gold to me.

Regards,

Adam Smith Midland ON

The copper level in ductile iron will directly affect how much pearlite is formed. Pearlite level determines tensile, yield and elongation. There are

3-4 grades that could be produced "as-cast" meaning no post-casting heat treat. Listed below are the grades, an approximate copper content, and approximate pearlite content. To see the pearlite would require polishing and etching, then viewing under a microscope. Everything below is assumed that the nodularization process went well, using a good foundry practice. For each grade the 1st number is the tensile strength in ksi (1000 psi increments), the 2nd number is the yield strength in ksi (point where deformation occurrs) and 3rd number is the elongation (how much the iron will stretch before breaking):

Grade 60-40-18 - Cu less than 0.08% - pearlite nil to 5% Grade 65-45-12 - Cu 0.05 to 030% - pearlite 20 to 30% Grade 80-55-06 - Cu 0.55 to 0.65% - pearlite 45 to 75% Grade 100-70-03 - Cu 0.70 to 0.85% - pearlite 70 to 90%

So, the copper does not cause problem per se, but it does influence the tensile, yield and elongation.

International Nickel Company (INCO) produced several types of Nickel-Magnesium alloys. Ductile iron was discovered by Keith Millis in the

1940's. I put an article on Keith Millis on Wikipedia.

INCO initially had a patent on ductile iron and almost 100% of it was produced using their master alloy. Two common ones were INCO #3 and INCO #4. One has 57% Nickel, 5% Magnesium and the balance iron. The other is

95% Nickel and 5% Magnesium. Both are used by adding the proper amount to the ladle of iron. The first one with the iron is lower cost. The second one has a higher density, and more easily "sinks" to the bottom of the ladle. There is less magnesium fuming and flaring. But, the cost difference can be great.

Before adding Nickel the sulfur needs to be removed from the iron. Calcium Carbide can be used (same stuff used in miners lamps). A special ladle can be built, using a GAZAL plug. Nitrogen is bubbled through the bottom of the ladle and the calcium carbide reduces the sulfur in the iron.

In a regular gray iron the sulfur can be 0.05 to 0.12% (typically). For good practice the sulfur should be lowered to 0.020% or less before adding magnesium. If desulfurization is done with calcium carbide the sulfur will go below 0.020%. No need to analyze.

With desulfurized iron the amount of magnesium to make the nodular or ductile iron will be about 0.040%. But, when the magnesium is added perhaps

30 to 50% is lost, i.e. the "recovery" is about 50 to 60% (sometimes less).

If anyone wants further detail instrustions, on a sketch of desulfurizing ladles, etc. please PING me or post the request.

Mark

They always used to tell me it was patented, but I haven't talked to them since the late '70s.

Here are some references:

Look up "meehanite patent" on Google, without quotes, and you'll find a lot of others.

-- Ed Huntress

Meehanite:

Today, the Meehanite name is a trademark. A foundry can claim to make "Meehanite" iron if they pay a licensing fee to the Meehanite corporation. The original 'Meehanite metal' was invented in the US in 1922 by Gus Meehan, who patented its manufacture and production. At first, Meehan was trying to discover a way to reduce annealing time of black heat malleable iron. He added calcium silicide to the iron. Instead of coming up with a solution to his original problem he noted that the iron was more like a gray iron, instead of the malleable iron he was trying to produce. After casting, malleable iron parts, when fractured, have a white appearance (hence the name white iron). After annealing malleable iron the carbon which is in solution in the iron precipitates into graphite clusters. The iron carbide (i.e white iron) is thus "softened" and becomes malleable or bendable. What Meehan noted is the calcium silicides were potent and caused the graphite to form readily. Gray iron was already produced by foundries but consistency was lacking. Using the calcium silicides the process was controlled. There's a whole lot more to it but this is the basics. Meehan also came up with an inoculant (or family of inoculants) called "Caloy". We still use some Caloy today but it's not sold by Meehanite.

At one time Meehanite corporation owned foundries and also licensed other foundries. Meehanite may be incorporated in several countries. The (US) Meehanite Metal Corp doesn't own any foundries outright (that I am aware of). Today they still license foundries.

With a license a "Meehanite Foundry" may produces many type of irons that are called Meehanite. There are ductile irons, gray irons, white irons and alloyed irons. There may be others. Within each broad grouping of types there are several grades. For example within the family of types known as ductile iron, there are four types: SP-80, SH-100, SF-60 and AQS. These grades will also meet A.S.T.M. (American Society of Testing and Materials) and other specifications.

Without a license a foundry cannot produce "Meehanite" but they could produce an iron that is equivalent, behaving the same, and also meeting A.S.T.M. (American Society of Testing and Materials) and other specifications.

There's not any "magic" or chemistry difference between Meehanite or non-Meehanite iron. But, if a designer puts "Meehanite" on a blueprint then it means the casting has to be produced at a Meehanite foundry.

There are advantages for foundries to be Meehanite licensed. For example Meehanite provides technical services, literature, and technical advice, seminars, training, etc. Like anything else the cost of being licensed has to be weighed against the benefits obtained.

Mark

Tremendous information. Thanks.

Have you done this, or do you know anyone who has done this in a home or small shop foundry? Do you know of any North American (preferably Canadian) suppliers for small (ie lb sized orders, not hundredweight or tons) quantities of the ni-mag alloys? (It may be that inco actually will sell in smaller quantities, I'll post the information after I enquire during the week.)

Adam Smith, Midland ON

The supplier you might try is TecPro Corporation

They don't list the NickelMag on the website but they sell it. I don't know what their minimum quantity is. They also are proponents of another process for making ductile iron, the cored wire process. I forgot about mentioning that process in the earlier post. They indicate sulfur levels can be up to

0.09% for that process. I don't have any personal experience with the process. Normally machenery is involved but you might be able to buy the cored wired and do it by hand. Don't know for sure.

Remember they are a commercial house so they might not want to sell only because the costs involved in setting up a small acount might mean the cost to you is quite high.

When using Nickel Mag, the smallest ladles we treat are in the 5,000 pound range. But, we used INCO mag at another foundry and treated 250 pound ladles of ductile niresist. I see no reason why the process could not be extended down to perhaps 50 or 100 pound ladles. I don't know what the lower limit might be. Maybe 20 pounds?

If I were trying to treat a 50 pound ladle, using Nickel Mag (57% Ni product) to convert the iron into ductile iron, I would first want to get my iron to a low sulfur state. So I would need to know your melting process. If sulfur is above 0.020% then I would desulfurize. To do this tap the 50 pounds into a preheated ladle. Before tapping put 2-3 pounds of calcium carbide (fine mesh) into the ladle. After the ladle is full skim off the resulting slag from the desurfurization. There will be fuming. Wear a breathing mask.

After the skim off of the calcium carbide, then do the mag treatment. Put about 1/2 pound of Nickel Mag (57% Ni product) into the iron. If you can construct a steel device to plunge the nickel that would be good. Make a steel rod with a cup on the end. Put the nickel mag ingot into the iron, then use the steel plunger to push it to the bottom. Always make sure tools are completely dry. Wear protective equipment. Work where there is plenty of room to move out of the way if there is any splashing. The magnesium flaring is bright. Might need welder's goggles. Don't look at the flaring directly for long periods of time. As the flaring begins to subside, add 3 to 4 ounces of finely crushed ferrosilicon inoculant. OK to plunge this also for good mixing.

Skim off ladle and pour, complete pouring within 10-12 minutes. Beyond that the magnesium addition starts to "fade". This means the magnesium effect goes away and the iron won't be good ductile.

I'd need to know more about your operation to tell you more specific instructions.

Mark

I think I read somewhere that calcium tends to denodularize the carbon; is there anything wrong with putting in too much carbide?

To continue my thought, if you made your own, with copper, alloyed maybe 10% (which has a rather low melting point of around 726°C; the intermetallic Cu2Mg at 16% might be better to use), you could get ductile iron, and approximately half pearlite structure? No good for remelts of course, if you want the same pearlite structure.

Alternately, you could melt nickels (25% Ni, 75% Cu), but that has nearly as much copper anyway.

FYI, I'm working on a small induction heater/furnace, so some day - surely within a year, I'll be melting this stuff clean and easy.

Very fun stuff though ;-)

How's the recovery of silicon between remelts?

Because it evaporates entirely, right?

Hey, what's the scoop on aluminum in iron - the phase diagram looks okay to

20%, and I've seen one entry in Matweb for a high temperature cast iron in that range, but not much else. Anything from the guru?

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

Hello Mark,

I can't tell you more about my operation at this point, because I don't have one. I am quite serious about gearing up and learning how to do this, though. Part of my objective in posting was that my "gearing up" actually provide me with the capabilities I'm look to acquire (at least eventually). The excellent information you've provided is a great help. I would imagine that there are people all over the world that have saved your answers to disk.

Many Thanks,

Adam Smith Midland, ON