26) Given the T-T-T curve below, select the process that will result in a microstructure of nearly all bainite. C. Cool to 400°C, hold for 20 seconds, then quench to room temperature Cool to 500°C, hold for 10 seconds, then quench to room temperature Quench to 125°C, hold for 10 seconds, then reheat to 600°C for more than 100 seconds d. Cool to 725°C, hold for 1,000 seconds, then quench to 125°C Cool to 600°C, hold for 1 second, the quench to room temperature f. none of the above 900 Temperature (°C) 800 A+C 700 A+P 600 500 A+B 400 A 300 200 M(start) M(50%) 100 M(90%) TT 1600 1400 1200 1000 800 600 50% 0 1 10 102 103 104 105 106 Time(s) 400 200 Temperature (°F) 27) Fatigue failure situations are typically dependent upon which combination of the following factors? Slip plane, slip direction, and orientation of the applied load b. Yield strength, elastic modulus, and ductility of the material c. Temperature, time, and applied stress d. Stress amplitude, frequency of loading, and number of cycles e. Flaw size, crack-tip radius, and Kic value of the material 28) Using the Fe-C phase diagram (included in the equation sheet), calculate the phase weight fraction of Fe C expected in a pearlitic steel microstructure under equilibrium conditions assuming a bulk composition of 0.45 wt% carbon. a. 93.6 wt% Fe3C b. 66.3 wt% Fe C C. 36.7 wt% Fe3C d. 6.4 wt% Fe₂C e. 4.5 wt% Fe3C