Question

14) 4. Using the attached iron-iron carbide phase diagram, answer the following: a) Upon slow cooling a 1.0 wt% carbon steel from 900°C: i) At what temperature does the carbide phase appear? ii) How much carbide is present at 729°C? iii) How much carbide is present at 725°C? b) Upon slow cooling a 0.5 wt% carbon steel from 900°C to 725°C: i) What are the compositions and quantities of the two phases present? ii) What are the compositions and quantities of the two types of grains present?

Answer 1

4.0) ) Upon slow cooling from a 1.0 wts. ( steel from 900°C; the Carbide (Fe3C) phase appear at 800°C. Cfrom drageam) in At 729°c (ex = concentration of x Co=1% (0.76%) (6.7%) mass fraction of Carbide (Fez C) at 729°C, 1-0.76 (Applying lever ente) mrest Co-Cr Cresc-Cr 6.7 -0.76 imreze 0.04040 4.04 % % of carbide present at 729°c (ii) At 725°C. Creil Cozly. O Ca " (6.7%) (0.022%) mass fractions of Carbide (Fezc) , at 725°C, Co-Ca 1-0-022 (fex-ca 6.7 -0.022 (Applying lever ente) Mreal Mresc = 0.14645 . : % of Carbide present at 925°c = 14.645% (b) (i) The a phases present are l-feseite and cementite (fe3c). composition of d-fresite, C = 0.022 % 2 from diagram Composition of fest (fez c = = 6.7% } (reze (0.5) (6-7) Cx o Co (0.022)