CHAPTER XV. 

 ENGINEERING MATERIALS. 



IRON AND STEEL. The following definitions were adopted by the Committee on the 

 Uniform Nomenclature of Iron and Steel of the International Association for Testing Materials, 

 September, 1906. 



Cast Iron. Iron containing .so much carbon or its equivalent that it is not malleable at any 

 temperature. The committee recommends drawing the line between cast iron and steel at 2.20 

 IK.T cent carbon. 



Pig Iron. Cast iron which has been cast into pigs direct from the blast furnace. 



Bessemer Pig Iron. Iron which contains so little phosphorus and sulphur that it can be used 

 for conversion into steel by the original or acid Bessemer process (restricted to pig iron containing 

 not more than o.io per cent of phosphorus). 



Basic Pig Iron. Pig iron containing so little silicon and sulphur that it is suited for easy 

 conversion into steel by the basic open-hearth process (restricted to pig iron containing not more 

 than i.oo per cent of silicon). 



Gray Pig Iron and Gray Cast Iron. Pig iron and cast iron in the fracture of which the iron 

 itself is nearly or quite concealed by graphite, so that the fracture has the gray color of graphite. 



White Pig Iron and White Cast Iron. Pig iron and cast iron in the fracture of which little 

 or no graphite is visible, so that the fracture is silvery and white. 



Malleable Castings. Castings made from iron which when first made is in the condition of 

 cast iron, and is made malleable by subsequent treatment without fusion. 



Malleable Pig Iron. An American trade name for the pig iron suitable for converting into 

 malleable castings through the process of melting, treating when molten, casting in a brittle state, 

 and then making malleable without remelting. 



Wrought Iron. Slag-bearing, malleable iron, which does not harden materially when suddenly 

 cooled. 



Steel. Iron which is malleable at least in some one range of temperature and in addition is 

 either (a) cast into an initially malleable mass; or, (b) is capable of hardening greatly by sudden 

 cooling; or, (c) is both so cast and so capable of hardening. 



Open-hearth Steel. Steel made by the open-hearth process, irrespective of carbon content. 



Bessemer Steel. Steel made by the Bessemer process, irrespective of carbon content. 

 ' Blister Steel. Steel made by carburizing wrought iron by heating it in contact with car- 

 bonaceous matter. 



Crucible Steel. Steel made by the crucible process, irrespective of carbon content. 



Steel Castings. Unforged and unrolled castings made of Bessemer, open-hearth, crucible 

 or any other steel. 



Alloy Steels. Steels which owe their properties chiefly to the presence of an element other 

 than carbon. 



Classification of Iron and Steel. The limits of carbon, the specific gravity and properties 

 of iron and steel are as follows: 



Per cent of Carbon. Specific Gravity. Properties. 



Cast Iron 5 to 1.50 7.2 Not malleable, not temperable 



Steel 1. 50 to o.io 7.8 Malleable and temperable 



Wrought Iron 0.30 to 0.05 7.7 Malleable, not temperable 



It will be seen that the percentage of carbon alone is not sufficient to distinguish between steel 

 and wrought iron. The softer grades of steel resemble wrought iron. Very mild open-hearth 

 steel is often sold under the trade name of " Ingot Iron," and is reputed to have many advantages 

 over structural steel, most of which properties it does not possess among which is the ability to resist 

 corrosion. 



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