THE METALLOGRAPHY OF METEORIC IRON 



33 



With no carbon the final product would be homogeneous granular 

 ferrite; but when an iron-carbon alloy with less than 0.80 percent 

 carbon in solution in cooling crosses the line DE (the A3 line) , grains 



1600 



1400 



1200 



cr 



<: 



2 3 



PER CENT CARBON 



Figure 3. — The iron-carbon equilibrium diagram. 



of pearlite (the eutectoid of ferrite and cementite) appear among 

 the ferrite grains (pi. A, fig. 2). This is hypoeutectoid steel. 



As the percentage of carbon rises, the areas of pearlite increase, 



