344 STKKXtiTll or MATKUIAI.S or C()\STi:i'(Tlo\. 



possessed to a very slight extent by the low carbon cr 

 mild steels. 



The steels may be divided into : 



Mild or soft steel, containing 0'35 to O'GO per cent, 

 of carbon. 



Hard steel, containing 0'60 to 0'80 per cent, carbon. 



Hardest steel, containing 0'80 to 1'50 per cent, 

 carbon. 



Each of the above is produced in three or more 

 grades. Besides these simple steels, there are several 

 special steel alloys, consisting of carbon steels alloyed 

 with a third constituent. These are : 



Chrome steel. 

 Manganese steel. 

 Nickel steel. 

 Tungsten steel. 

 Aluminium steel. 



(3) Cast Iron. Consisting of iron and 1'50 to 6 '00 

 per cent, of carbon, as well as small quantities of 

 manganese, silicon, sulphur, and phosphorus ; non- 

 malleable at any temperatures, easily fusible, and not 

 capable of being hardened or tempered in the ordinary 

 way. 



Cast irons may themselves be divided into : 



(A) Foundry Pig. Containing carbon, phosphorus 



and silicon. 



(B) Forge Iron. Containing carbon, sulphur, and 

 . phosphorus, and little silicon and manganese. 



(c) Spiegeleisen. Containing chiefly manganese and 

 silicon. 



These alloys and carburets of iron will now be 

 considered in detail. 



