Plate A 



(Artificial Irons) 



1. Ferrite. Practically pure iron, showing the characteristic microstructure of irregular 

 polygonal grains. Strong nital etching; X 60. 



2. Hypoeutectoid steel (carbon 0.15 percent). It consists predominantly of ferrite. The 

 black areas are pearlite, which when resolved at higher magnification appear as in figure 4. 

 Strong nital etching; X 60. 



3. .£M/^<:/oz(f .fi^^"/ (carbon 0.85 percent). It is composed entirely of the ferrite-cementite 

 eutectoid, pearlite. Light nital etching; X 60. 



4. Pearlite (carbon 0.85 percent). A portion of the structure shown in figure 3, consisting 

 of lamellae of ferrite (dark) and cementite (light). Light picral etching; X 600. 



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