Pure iron (Fe) undergoes an allotropic transformation at 912°C. Upon heating from a BCC (a ferrite phase) to an FCC (y a

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Pure Iron Fe Undergoes An Allotropic Transformation At 912 C Upon Heating From A Bcc A Ferrite Phase To An Fcc Y A 1 (266.72 KiB) Viewed 10 times

Pure iron (Fe) undergoes an allotropic transformation at 912°C. Upon heating from a BCC (a ferrite phase) to an FCC (y austenite phase), this transformation is accompanied by a change in density (and volume). With the addition of carbon, both hardness and tensile strength can be improved by solid solution strengthening mechanism. The iron - iron carbide phase diagram is shown below 1600 1493°C L 1400 1200 1000 Temperature (°C) 1538°C 8 1394°C Y, Austenite 912°C y+L 0.76 2.14 1147°C 4.30 y + Fe3C 800 0.022 600 a, Ferrite a + Fe3C Cementite (Fe3C) 1 400 0 (Fe) 4 5 6 6.70 3 Composition (wt% C) 1. Compute the percentage density change associated with the transformation of iron from BCC to FCC at 912°C. 2. What is the maximum solubility of carbon atoms in iron in solid-state? 3. What is the compositional range of carbon for the hypoeutectoid steel? Considering the iron-carbon alloy with 1wt%C, please answer questions 4 - 6: 4. What are the melting emper and eutectoid temperatu of this alloy? 5. What is the weight fraction of the a-ferrite in pearlite after completely cooled to room temperature? 6. What is the total weight fraction of the cementite after completely cooled to room temperature? 727°C