Use the following FeFe3C phase diagram to answer questions 6

Use the following Fe-Fe3C phase diagram to answer questions 6-10 Steel containing 0.5% C is classified as Hypoeutectic Hypereutectic Hypoeutectoid Hypereutecoid Maximum solubility of Carbon in alpha-ferrite is .0.77%C 2.11%C 0.0218% C 2.11%C What phases) are present at 728 degree C for AISI steel 1040 (0.40%C) alpha-ferrite gamma-austenite both alpha-ferrite and y-austenite None of the above Amount of a-ferrite in question is 50.5% 49.5% 0.0218% 0.77% Eutectoid reaction in this phase diagram takes place at 4.3% C 2.11%C 0.77%C None of the above

Solution

6.ans is c- hypoeutectoid plain (A 0.5% C hypoeutectoid plain-carbon steel is slowly cooled from 950°C to a temperature just slightly above 723°C. Calculate the weight percent austenite and weight percent proeutectoid ferrite in this steel).

7.ans is c-0.0218% (As indicated by the Fe – Fe3C phase diagram, carbon is only slightly soluble in ferrite, reaching maximum solid solubility of 0.02% at 723°C.

8.ans is a- ferrite (This phase is an interstitial solid solution of carbon in the BCC iron crystal lattice. As indicated by the Fe – Fe3C phase diagram, carbon is only slightly soluble in ferrite, reaching maximum solid solubility of 0.02% at 723°C)

9.ans is c-0.0218% (This phase is an interstitial solid solution of carbon in the BCC iron crystal lattice. As indicated by the Fe – Fe3C phase diagram, carbon is only slightly soluble in ferrite, reaching maximum solid solubility of 0.02% at 723°C. The solubility of carbon in ferrite decreases to 0.005% at 0°C)

10.ans is a- 4.3%c (At the eutectic reaction point, liquid of 4.3% forms austenite of 2.08% C and the intermetallic compound Fe3C (cementite) which contains 6.67 % C. This reaction which occurs at 1147°C can be written as Liquid (4.3% C ) (2.14% C ) Fe C (6.7% C ))