Thanx for all the knowlegable replies to all the earlier questions. Now what is malleable iron?

iron that the post office will deliver

http://en.wikipedia.org/wiki/Malleable_iron

Mornin Danny

:blink: LOL. Danny, Mark might be on to something, there. :D

The Wiki link pretty much says it all.

iron that the post office will deliver .............................That's funny :wacko:

So a pour of bog iron, ductile iron, and limestone will make a pig of malleable iron with round carbon balls.

Bog iron is a raw material -- a form of iron ore. It's not something you pour; it's something you can smelt into iron by exposing it to high temperature in a carbon rich atmosphere, which strips away the oxygen in the ore and leaves behind metallic iron. Depending on the smelting process used, the end product can be liquid iron with high carbon content (which is then poured into "pigs" to solidify, becoming pig iron), or it can be a "bloom" of solid iron (with relatively low carbon content) and slag, which you can then further refine in any number of ways to form various grades of wrought iron, shear steel, crucible steel, etc. Limestone has often been used as a flux in smelting iron ores into pig iron in blast funaces, and in furnaces that convert pig iron into steel. Its purpose in those furnaces is to combine with impurities in the iron and carry them away as slag.

Ductile iron is a finished product that you get by adding magnesium, cerium, or various other metals to molten cast iron just before you pour it into a mold. (Pig iron might be the raw material for this process.) This causes a reaction that makes the carbon in the cast iron form into balls (spheres) of graphite. It apparently also causes some pretty impressive fireworks. Ductile iron is not generally a raw material used for producing malleable iron, although I suppose scrap ductile iron could be remelted for that purpose.

Malleable iron is a separate finished product that you can get by pouring cast iron into a mold and allowing it to cool fairly quickly, forming white cast iron, then subjecting the finished product to a medium-high heat for a long period of time, which allows the graphite to migrate through the iron and gather together in rough spheres. (Pig iron might be the raw material for this process as well.) It is similar to ductile iron, but not as tough.

http://www.dipra.org/ this has a picture of both types of iron under a microscope and shows how much difference there is in the graphite formation. Be sure you go over and click on "Ductile Iron"

Here's a good one, too. Be sure to click through to the next page as well. http://www.georgesbasement.com/Microstructures/CastIronsHighAlloySteelsSuperalloys/Lesson-1/Specimen03.htm