Question

The phase diagram for the iron-carbon Fe-C system is shown below. use it to answer the following questions

9. The phase diagram for the iron-carbon (Fe-C) system is shown below. Use it to answer the following questions. (2 points each) Compositien (at% Ch 20 1600 1538 C 2493 C 1400 2500 1394 C 1147 C 1200 2.14 4.30 Austenite 2000 1000F y+Fe C 912 C 1500 800 727 C n 76 0.022 600 . Ferrite a+FesC Cementite (FegC) 1000 400 6.70 5 Composition (wt% C) (Fe (a) How many different solid allotropes (phases) does pure iron have? (b) What is the maximum carbon solubility of carbon in austenite? (c) What is the maximum carbon solubility of carbon in ferrite?

a) How many different solid allotropes (phases) does pure iron have?

b) what is the maximum carbon solubility of carbon in austentite?

c) what is the maximum carbon solubility of carbon in ferrite?

d)On cooling the following phase reaction occurs at 0.76% C and 727*c y--> alpha + Fe3C. On cooling what phase reaction occurs at .16% C and 1493*c?

e)For a plain carbon steel contaning 1% carbon at 1400*c what phases will be present? f)fir a plain carrbon steel containing 1% carbon at 1400*c what is the composition of each phase present?

g) For a plain carbon steel contaning 1% carbon at 1400*c what is the weight fraction o each phase present?

h) what temperature does ferrite transform to austentite in pure iron?

i) For an iron-carbon alloy in equilibrium containing 2% carbon at 900*c, what phases are present?

j) For the same allow and temperature, what are the compositions of the phases present?

k) For the same alloy and temperature what are the relative amounts of the phases present?

Answer 1

a). Pure iron exists in three solid allotropes- alpha iron, gamma iron and Delta iron.

b). Maximum solubility of carbon in gamma austenite is 2.14%.

C). Maximum solubility of carbon in alpha iron is 0.022%.

D). At 0.16% C and 1493°C, peritectic reaction occurs. At this point Delta iron and liquid iron convert into gamma austenite.

E). At 1%C and 1400°C, liquid and gamma austenite phases are present.

F). At 1% C and 1400°C, liquid phase is approx 20% and gamma austenite is 80%.

H). At 912°C, ferrite transform into austenite in pure iron.

I). At 2%C and 900°C, gamma austenite and cementite phases are present.

J). At this composition, gamma austenite is approx 90% and cementite is 10%.