Steel containing less than this quantity of carbon consists typically of kernels of pearlite surrounded by envelopes of ferrite (see Alloys, Pl., fig.
When the mass is cooled, the carbon changes over into the condition of cementite as usual, partly interstratified with ferrite in the form of pearlite, partly in the form of envelopes enclosing kernels of this pearlite (see Alloys, Pl.
Both the primary and eutectic austenite have changed in cooling into a mixture of pearlite and pro-eutectoid cementite, too fine to be distinguished here.
The pearlite when highly magnified somewhat resembles the lead-tin eutectic of fig.
The percentage of pearlite and of free ferrite or cementite in these products is shown in fig.
Would have consisted chiefly of graphite with pearlite and ferrite (which are all relatively soft bodies), if thus chilled and annealed consists of cementite and pearlite.
Here the black bat-like patches are the masses of pearlite plus proeutectoid cementite resulting from the splitting up of the primary austenite.
FIC. r3.--(Stoughton.) Meshes of pearlite in a network of cementite from hyper-eutectoid steel.
Carbon-Content of Hardened Steels.-Turning from these cases in which the steel is used in the slowly cooled state, so that it is a mixture of pearlite with ferrite or cementite, i.e.
Steel and white cast iron with more than this quantity of carbon consist typically of kernels of pearlite surrounded by envelopes of free cementite (see Alloys, Pl., fig.