I started to melt some Cast Iron today

[oldgoaly]

How much iron did you make? was it the same type you put in last time? running both lp and diesel? 35 minutes if fast! what are doing with the left overs?

[Rickabilly]

Back in my steelworks days we used to make very good use of White Iron or as we called it chilled Iron, Melting iron was never a problem for us as we got 210tons every 42 minutes out of our very own pair of blast furnaces. we'd average 19 heats a day counting in down time etc.

At any rate we used to cast a lot of stuff directly into the floor of the foundry which was eighty years deep with greensand pits and old moulds and punctuated with railway lines and jib crane posts for bringing in torpedo ladles and lifting out patterns and rough castings.

When casting new pot ladles, which were good for holding 50+ tons of cast iron or steel after lining we used to "Chill" the lifting lugs on purpose, it is easier than you might first think, all that needs doing is adding big ole copper plates called "Chills" or sometimes "Clinkers" or large disc shaped items with a central Leg on the back, the chills were added just after the first layer of fine sand was laid over the pattern, keeping in mind the size of the patterns the fine sand layer moght have been about an inch thick, then the chils are layed into it and tamped down then the coarse sand went in on top, this way certain areas of the mould conducted the heat away very rapidly causing, well..."Chilled" spots that allowed the areas to wear far better than grey iron ever could.

Incidentally the pots I'm thinking of were cast in three or four rings and then welded together and then welded to a base, each ring was about six feet in diameter and two to three feet high/deep, It was great to watch a pour we used to control pouring temperature to an accuracy of plus or minus four degrees c and for good chilling use about twenty degrees of super heat, I'd guess the chilling seen above was the result of a cold pour, but it could have been many things.

Regards
Rick

[dallen]

I melted enough to of made two of the parts that I was after plus fill all the gating. I always run both oil an gas when melting iron the propane gives the burner the kick that takes it into a reasonable amount of time instead of it taking all day.

what doesn't go in the mold gets poured into the ingot mold some 2 inch angle iron that I have welded up to make 4 inch long ingots out of. I find that size works in all my crucibles except for the little one then I need some thing like 1/2 inch rod cut up into 1.5 inch pieces.

DA

[Rickabilly]

Incidentally this thread and all the talk about chilled or white iron, has made me think about my Metallurgy lessons from twenty years ago and I thought it might be interesting to those here to know a little more about why cast iron acts as it does, when really it's just Iron and carbon pretty much like steel is.

1. Cast iron has a lot of carbon compared to steel so much that the carbon clumps together into flakes of graphite when cooled slowly(precipitation) but even so, this graphite is in a matrix of steel so why is it so easy to machine? well, due to the other impurities mainly sulphur the "steel" matrix is a form of free machining sulphurised steel similar to F12L07 (or free machining leaded steel).

2, Chilled iron is when the the iron goes from it's fully liquified state where the carbon is bonded to the iron to a solid state very quickly, the "Iron Carbides" that are present in liquid form normally can't exist as solids but when rapidly cooled, there isn't enough time for the carbides to break down, so we end up with solid Iron carbide, now think about how hard silicon carbide can be and you'll realise why chilled iron is so tough, many people say that white iron has the carbon chilled out of it, or that there is no carbon present, but that isn't true the carbon is there but so well bonded that it can't be seen. You may have heard of "Pearlite" grains that are present in hardened steels well these are layered crystals of ferrite and carbides that also give great strength but with more ductility from the ferrite(pure iron) layers, incidentally they are called pearlite as a result of how they look under a microscope, they look kind of pearl like, very pretty.

3. more commonly known is why grey iron doesn't need lubricant, where many other metals do, this is as a result of the graphite flakes falling out of the surface as the material is machined and so lubricating the cutting or wearing action.

4, spheroidal graphite iron, or malleable iron is where additives (usually magnesium) are added to cast iron and these help the graphite to form little balls or spherites, these balls form less stress concentration points than flakes and also the process eats up some of the sulphur which reduces the free machining characteristics of the steel matrix, these two factors combined makes the SG iron more malleable, less brittle and causes the little curly shavings seen only on SG irons.

Please keep in mind this is straight out of my memory, so go easy on me if there are any errors but hopefully it might help explain why certain things happen when casting iron.

Best regards
Rick

[dallen]

some of todays playing in the yard

[Rickabilly]

DA,
You are making me miss my Blast furnaces,

There is something about the smell of a Blast furnace, I still miss the smell after 16 years.

Nice work by the way.

Rick

[dallen]

your welcome, I am sorry that you miss the smell of burnt sulfur from the coke ovens thou

David

[Rickabilly]

Oh, there is absolute nothing like the smell of freshly quenched coke.

Rick

[oldgoaly]

how does burnt diesel and propane smell? have each one in the memory bank but together?
I can get the smell of burning coal and coke with the forge, I bought some petro-coke, it's too fine for a cupola so when I get the forge going I put a shovel full in the coal.

[DaveH]

Really interesting DA Hot Stuff!

DaveH