When cooled slowly below 670 degrees, martensite yields a heterogeneous mixture of pearlite and ferrite (or cementite, if the original mixture contained between 0.
Martensite, Troostite and Sorbite are the successive stages through which the metal passes in changing from austenite into ferrite and cementite.
Turning from these cases in which the steel is used in the slowly cooled state, so that it is a mixture of pearlite with ferriteor cementite, i.
The iron thus liberated, as the ferrite of this pearlite, changes simultaneously to [alpha]-ferrite.
The growth is continually destroyed by the hammering, which should consequently be continued down to the upper critical temperature when the austenite crystals break up into ferrite and cementite.
Pearlite is a definite conglomerate of ferrite and cementite containing about six parts of the former to one of the latter.
Apparently the quick cooling prevents the normal change back to definite and sizeable crystals offerrite and cementite.
The cementite, although adding to the tensile strength, is very brittle and the strength of the pearlite is the combination of the ferrite and cementite.
As soon as a little carbon enters the alloy and a soft steel is formed, small angular areas of pearlite appear at the boundaries of the ferrite crystals (Fig.
The increased amount of free ferrite arranges itself about the crystals as envelopes.
It is possible to change the relative sizes of the ferrite and cementite crystals by heat treatment.
A final steel will be composed of pearlite; ferrite and pearlite; or cementite and pearlite, according to the carbon content.
From this combination, we are able to get a very strong ferrite matrix and a very hard tough cementite.
We see, therefore, that when martensite is allowed to cool slowly, it yields a heterogeneous mixture either of ferrite and pearlite (when the original mixture contained up to 0.
The triangular structure characteristic of cast steel showing ferrite and pearlite (enlarged 50 times)] [Illustration: Courtesy of E.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "ferrite" in a variety of sentences. We hope that you will now be able to make sentences using this word.
