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Author
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Topic: What is nodular iron....
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Buster
Gearhead Posts: 1553
From: Hurricane alley
Registered: May 2002
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posted 01-31-2004 07:32 PM
   
.... precisely that is. What is it with regards to Ford crankshafts, blocks and rear carriers?My understanding is nodular iron has more nickel in the casting. However, recently I've heard that magnesium is added and this creates nodules in the grain structure. What is the real story?
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Dubz
Gearhead Posts: 1890
From: Manitoba Canada
Registered: Oct 2002
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posted 01-31-2004 07:58 PM
by definition nodular is small rounded lumps of a mineral or mixture of minerals, usually harder than the surrounding rock or sediment.So it may be either or both... for rear ends
"Standard or WAR cases, were cast in gray cast iron which has a grain structure that does not have the best shear strength characteristics. The N stands for nodular iron, which is made by adding magnesium to molten iron. What this does is change the grain structure from flakes to nodules - much stronger and less likely to fail under shear load."
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Red65
Gearhead Posts: 115
From: Northglenn, CO, USA
Registered: Jul 2002
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posted 01-31-2004 10:26 PM
Putting on my enginerd hat:Nodular cast iron refers to ductile irons that have little graphite spheres or nodules in the iron matrix. These nodules act similiar to the carbon in steel, and thus give nodular iron properties similar to steel (higher strength, ductility, toughness, and hardenability). My materials book shows that the grey cast irons typically used for engine blocks are about 1/3 the strength nodular irons. The formation of graphite nodules is done by tightly controlling the amount of trace sulfur, phosphorus, and other impurities in the alloy, and by using slow cooling rate when you cast the material. Magnesium doesn't create the nodules, but may be added to the alloy to adjust properties to suit. If anyone cares, I could scan some pages from my old materials textbook that actually show the graphite nodules.
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Dubz
Gearhead Posts: 1890
From: Manitoba Canada
Registered: Oct 2002
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posted 01-31-2004 11:25 PM
quote:
Originally posted by Red65:
Putting on my enginerd hat:Nodular cast iron refers to ductile irons that have little graphite spheres or nodules in the iron matrix. These nodules act similiar to the carbon in steel, and thus give nodular iron properties similar to steel (higher strength, ductility, toughness, and hardenability). My materials book shows that the grey cast irons typically used for engine blocks are about 1/3 the strength nodular irons. The formation of graphite nodules is done by tightly controlling the amount of trace sulfur, phosphorus, and other impurities in the alloy, and by using slow cooling rate when you cast the material. Magnesium doesn't create the nodules, but may be added to the alloy to adjust properties to suit. If anyone cares, I could scan some pages from my old materials textbook that actually show the graphite nodules.
If you want a real good look at some nodules find a meteorite, the cooling process in them takes an extremely long time, and creates incredible nodules
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NewRider
Journeyman Posts: 52
From: Terre Haute, IN
Registered: Jan 2004
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posted 02-01-2004 10:14 AM
quote:
Originally posted by Dubz:
If you want a real good look at some nodules find a meteorite, the cooling process in them takes an extremely long time, and creates incredible nodules
Maybe there are some in Mr FoMoGo's weedpatch. 
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Dubz
Gearhead Posts: 1890
From: Manitoba Canada
Registered: Oct 2002
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posted 02-01-2004 02:54 PM
quote:
Originally posted by NewRider:
Maybe there are some in Mr FoMoGo's weedpatch.
you can find them in museums....
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ironbullet
Journeyman Posts: 39
From: wytheville va usa
Registered: May 2003
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posted 02-01-2004 05:05 PM
dave shoe over at the fe forum said that in making nodular iron they throw the magnesium in the forge 1st then scrap iron ,then molten iron . When the magnesium starts too melt the whole room lights up , a very bright white light .. It's kinda tricky ya know cause magnesium is well nigh impossible too extinguish if it has access to free O2 , thus they put it at the bottom . If it caught fire it would burn the whole joint down ! ladle and all ! Interestingly FORD patented the process for making nodular iron ,and it wasn't till the patent expired that the other makers could use it. This is one of the reasons why the chevy crowd are so adamant about steel cranks ! their early iron cranks weren't worth 2 cents !
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