Talk:William Le Baron Jenney
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[edit] Iron vs steel
iron melts at 2750°F, steel at 2500°F
It's down to definitions. See the iron-carbon phase diagram: the line to worry about is the one separating the regions saying liquid or +liquid from everything else.
It's only pure iron that melts around 2750°F. But we're talking about cast iron, which typically has 2%-3.5% carbon, radically lowering the melting point. At 4.2% carbon, the whole lot melts at once at 2100°F, but all compositions of cast iron start getting soggy at this temperature).
In comparison, structural steels are typically carbon steel in the 'mild steel' range: 0.1%-0.25% carbon. A melting point of 2500°F and upward would be typical. Tearlach 17:43, 20 December 2005 (UTC)
- but the source referenced says that he used masonry, iron, and terra cotta for fireproofing: [1]
- That article vastly oversimplifies it.
- 1) You have the properties of the various alloys: cast iron is strong but brittle; wrought iron is slightly less strong, less brittle, but expensive; steel had the best properties of both and was cheap. So, as mass-produced steel became available, there was a drift toward steel-frame construction even minus the fire consideration.
- 2) There's what happens in a fire. Cast iron has a lower melting point, so steel was better on that basis. But also early construction used exposed girders that rapidly got hot in a fire, and hot cast iron shattered when quenched by fire hoses. Hence the move to a) steel, b) constructions where the girders (whatever they were made of) were clad in various insulating stuff.