A. (24 points) Describe the microstructure present in a 10110 steel after each step in each of the following heat treatments (note that i-iv are all individual heat treatments on different specimens, not a sequence of heat treatments on a single specimen; each will have a separate answer): i) Heat to 900 ºC, quench to 400 ºC and hold for 1000 sec. and then quench to 25 ºC. ii) Heat to 900 ºC, and then quench to 25 ºC. iii) Heat to 900 ºC, quench to 700 ºC and hold for 1 sec., quench to 600 ºC and hold for 1 sec, quench to 400 ºC and hold for 10 sec., quench to 300 ºC and hold for 100 sec, and then quench to 25 ºC. iv) Heat to 900 ºC, quench to 675 ºC and hold for 1 sec, quench to 300 ºC and hold for 1000 sec, and then quench to 25 ºC. b. (10 points) Describe the difference in final microstructures for 1080 and 1020 steels when cooled to room temperature at cooling rates of: i) 4 ºC/s ii) 25 ºC/s iii) 53 ºC/s iv) 120 ºC/s c. (6 points) Why is there a cementite start line for the 10110 steel but none for the 1050 steel?