Ductile Iron ? wassat?

[Old N Rusty]

Would someone tell me all about what is DUCTILE IRON ???

[Unforgivun]

I had to look it up the other day, because I had been told "cast iron's bad to hammer stuff on, mmmkay" and then I kept seeing stuff on kanye & sons being made of ductile iron like this cone or this leaf swage. So after some research it turns out that what makes regular old cast iron more apt to crack if hammered on is the shape of the graphite used to make it. Its either in flake form or just powder, no real shape to it. So when it creates the texture of the cast iron, it creates it almost like slate rock and thus when its impacted it forms a fissure. Ductile iron uses a Sphere shaped graphite and thus has an inner structure somewhat like a sponge only with teee-niny little holes. So its a lot more elastic than regular cast iron.

Heres the wiki link that I learned this mojo-jojo from Ductile Iron Wiki

[Francis Trez Cole]

it is case iron I have a green- mengel swedge block and it works real good. It can also take the hammering I have put it through. Cast iron anvils are not a good choice. For a swedge block it is ok.


There is a ductile iron society http://www.ductile.org/ here is some information from there web site. A lot of good reading.

Cast iron is brittle." is an outdated but widely held truism which mistakenly implies that all cast irons are the same, and none are ductile. In fact, Ductile iron is far more than a cast iron which is ductile. It offers the design engineer a unique combination of a wide range of high strength, wear resistance, fatigue resistance, toughness and ductility in addition to the well-known advantages of cast iron - castability, machinability, damping properties, and economy of production. Unfortunately, these positive attributes of Ductile Iron are not as widely known as the mistaken impression of brittleness is well known.

Types of Cast Irons
The presence of trace elements, the addition of alloying elements, the modification of solidification behaviour, and heat treatment after solidification are used to change the microstructure of cast iron to produce the desired mechanical properties in the following common types of cast iron.

White Iron
White Iron is fully carbidic in its final form. The presence of different carbides, produced by alloying, makes White Iron extremely hard and abrasion resistant but very brittle.

Gray Iron
Gray Iron is by far the oldest and most common form of cast iron. As a result, it is assumed by many to be the only form of cast iron and the terms "cast iron" and "gray iron" are used interchangeably. Gray Iron, named because its fracture has a gray appearance, consists of carbon in the form of flake graphite in a matrix consisting of ferrite, pearlite or a mixture of the two. The fluidity of liquid gray iron, and its expansion during solidification due to the formation of graphite, have made this metal ideal for the economical production of shrinkage-free, intricate castings such as motor blocks.

The flake-like shape of graphite in Gray Iron, see Figure 2.4, exerts a dominant influence on its mechanical properties. The graphite flakes can act as stress raisers which may prematurely cause localized plastic flow at low stresses, and initiate fracture in the matrix at higher stresses. As a result, Gray Iron exhibits no elastic behaviour and fails in tension without significant plastic deformation. The presence of graphite flakes also gives Gray Iron excellent machinability, damping characteristics and self-lubricating properties.

Malleable Iron
Unlike Gray and Ductile Iron, Malleable Iron is cast as a carbidic or white iron and an annealing or "malleablizing" heat treatment is required to convert the carbide into graphite. The microstructure of Malleable Iron consists of irregularly shaped nodules of graphite called "temper carbon" in a matrix of ferrite and/or pearlite. The presence of graphite in a more compact or sphere-like form gives Malleable Iron ductility and strength almost equal to cast, low-carbon steel. The formation of carbide during solidification results in the conventional shrinkage behaviour of Malleable Iron and the need for larger feed metal reservoirs, causing reduced casting yield and increased production costs.

[ThomasPowers]

Ductile iron works in the same way that drilling a hole at the end of a crack works. The graphite forms spheres as it solidifies. To propagate the crack now has to spread it's force along a wide face and exceed the strength of the material to essentially start a new crack.

Grey cast iron is absolutely full of lens shaped graphite inclusions which terminate in atomically fine "wedges" making it easy for a crack to zip through it---sort of the difference between pounding a steel ball through a log of wood to pounding a splitting wedge through one.

White cast iron AKA "chilled cast iron" is cooled so it solidifies before the graphite can start collecting in lenses but the carbides it's trapped in are both hard and brittle.

Ductile is useful for a lot of things and is often nice and cheap compared to casting steel. HOWEVER when someone says "cast iron" it is assumed they mean grey cast iron until proven otherwise!

[MattBower]

This is a topic that has interested me for a couple years, ever since I started to realize that not all cast iron is created equal. Ductile iron is pretty neat stuff. It's far superior to white and gray cast iron as far as mechanical properties. It's as strong as or stronger than lower carbon steels, and considerably tougher than other grades of cast iron (even malleable iron). It is used in some cases as a replacement for carbon steel, because it machines easily due to its graphite content, without the need to add sulfur, lead, etc., to the alloy. And of course it's cast, which is nice when you want to produce complex shapes that would be costly and time-consuming to machine. But it doesn't have quite the toughness of steel, particularly good hardened and tempered tool steels. There are some very reasonable quality anvils and struck tools made of ductile iron. I have a ductile iron tomahawk drift that has held up well in the face of some pretty severe beatings. A properly heat treated H13 drift would hold up vastly better, but would probably cost at least ten times as much.

Like steel, there are a number of different grades of ductile iron, each with their own properties. A ferrous metallurgist told me that some has an as-cast Rockwell hardness or 60 or more. Some grades can be quenched and tempered like steel. The same metallurgist had a TFS ductile iron anvil that he was very happy with; he said he just tried to be a little more careful about the edges, because they were likely to be more chip-prone than steel.

Here's a good reference concerning performance of metals used in anvils, including various steels and 80-55-06 ductile iron: http://www.hybridburners.com/documents/M-Main-on-anvil-steel.pdf

With all that said, you should still be very cautious about anything labeled "cast iron." If it doesn't say specifically what kind of cast iron, then it's probably gray or white iron, and it's not going to make a very good anvil or struck tool. If it's made of the good stuff, that's a selling point and they'll probably say it up front.

[Nakedanvil - Grant Sarver]

I believe TFS anvils are ductile iron. This past year I did some research on the product and I was amazed at the properties that can be obtained. It has the very fluid casting properties of cast iron and a wide variety of alloys, some that can be heat treated to 60 Rc! As I understand the process, just before pouring, the ladle of iron alloy is "inoculated" with a small amount of aluminum or magnesium which causes the carbon to form into spheroids. The alloys apparently can be heat treated much like steel alloys.

John Newman probably knows all about this stuff.

[jimmy seale]

i read...years ago that winchester arms eather "invented it" or used it for recievers. so they could cast them instead of forging/milling them.but don't quote me as i "disremember" lots of things in these latter years,jimmy

[MattBower]

i read...years ago that winchester arms eather "invented it" or used it for recievers. so they could cast them instead of forging/milling them.but don't quote me as i "disremember" lots of things in these latter years,jimmy

Yep. Winchester didn't invent ductile iron, but they did start using it for the receiver on the Model '94 in 1964. That went on until sometime in the '80s. (Winchester made a number of changes in 1964 to cut costs. A lot of folks perceive the pre-'64 quality as having been much better, which is why when you look at gun classifieds you'll see some Winchesters identified as "pre-'64.") It makes Model '94s from that era hard to refinish. Ductile iron apparently doesn't accept most forms of bluing very well (or maybe it's just that the surface doesn't polish up very nicely), so Winchester electroplated those receivers with iron, then blued them. Stripping the old bluing also strips the electroplating -- which leaves you with a problem.

[Old N Rusty]

IS fascinating this subject. Can it be welded with mild steel electrodes? certainly not a liquid tight but structurally sound welds? Under forge piping with a ductile lateral and driveshaft pipe is the nefarious plot

[MattBower]

DI is a form of cast iron, and only slightly less trouble to arc weld than other types of cast iron.

I'm not sure I understand your plan. What exactly is it that you want to build under the forge? Will it really benefit from using ductile? If mild steel would do, it'd be easier to get good welds.

[Old N Rusty]

I am scheming up a plan to use a 3" di lateral joint pipe fitting with the angled joint pointing up. The pipe(3" driveshaft) is flanged for a grainger 2" blower.welded to that pipe. which slips into the di fitting. This configuration insures no ash will build up in the blowerpipe. The bottom of the lateral fitting has a pipe piece with a flapper ash dump this joint might be tacked with e-6011 on top is a short piece that is welded to a steel flange taken from a BIG cable spool center. this flange is bolted to a brake drum forge underside a rotating chip breaker can be fabbed in this spot. Am i making it clearer? all #2 pencil and paper for now any input will be considered, and appreciated.

[Old N Rusty]

I slept on it, and was thinking of making this forge from this kind of scrap easily attainable items , brake drum firepot , could be on an old gas bbq carriage, this lateral and ash dump to be dissasembleABLE so it will fit in an ordinary auto trunk all slip in joints, light wt pipe ( driveshafts are great lightweight pipe and some are AL.) and a blower,either hand crank or el. OK?

[Bentiron1946]

I think that instead of ductile iron pipe for this application that plain old schedule 10 or maybe even schedule 40 black steel pipe would be easier to fabricate. Ductile iron makes great swage blocks, silversmithing stakes and the like but it doesn't weld all that well. It also makes great soil pipe and is acceptable for reclaimed water pipe below grade.

[K. Bryan Morgan]

In construction, ductile iron pipe is a standard item. I've used it many times for drainage, flow control, and to replace terra cotta, cast iron pipe in older homes. Some time building code requires it and sometimes it doesn't. It's rugged, lasts a long time and is hard to break.

[Bentiron1946]

It sure is hard to break! One year at the iron pour one of the guys brought in some 10" ductile iron pipe to add to the copula and we never did get it broke up. You hit it with an eight or ten pound sledge and the thing would bounce back and just about hit you in the face, real springy stuff that ductile iron pipe. Cast iron soil and water pipe will last for a century or more in contact with the ground and yes, it is used quite a bit for fire protection piping. Before I quit working over twenty years ago I had a project where we were tapping into a hundred year old cast iron water main at one of the states older institutions. That pipe was in great shape! Money had been allocated to replace it all the way back to the fire pump and tank building but it wasn't necessary. They cut a new tee into the line, bolted it home and poured a concrete thrust block and backfilled the hole. In some of the eastern cities in the US some of the cast iron water pipe was laid down in the early 1060's and is still going strong and it was just plain cast iron not ductile like we have now nor was it spun cast, it was just one big sand cast job for up to 72" pipe. I find it just amazing how well things were done in the past and we think an alien from outer space had to have had a hand in it when it was just plain old human perseverance.