The following isothermal TTT diagram describes a carbon steel at the eutectoid composition. Using this diagram draw and label cooling paths to produce (4 pts each): a) 25% coarse pearlite-25% bainite-50% martensite b) 100% bainite c) 100% martensite d) 50% martensite-50% austenite e) What is the composition of the austenite formed in part (d)? Temperature (C) 800 A Eutectoid temperature 1400 700 A 1200 600 P 500 400 A 300 1000 B 800 600 M(start) 200 50% M+A 400 M(50%) M(90%) 100 0 10-1 10 102 Time (s) 103 104 105 200 Temperature (F)