- 800 A 10 5 Isothermal Transformation Diagrams 325 Figure 10 23 The Complete Isothermal 1400 Transformation Diagram For 1 (116.57 KiB) Viewed 31 times
800 A 10.5 Isothermal Transformation Diagrams. 325 Figure 10.23 The complete isothermal 1400 transformation diagram for an iron-carbon alloy of eutectoid composition: A, austenite: B, bainite; M, martensite; P.pearlite. 1200 -Eutectoid temperature 700 A 600 P T 1000 500 B Temperature (°C) 800 400 Temperature A 300 600 Mistart) 200 509 400 M50%) M190%) 100 200 화 O 10 1 10 10 10 105 102 Time is)
Consider the 1080 eutectoid steel and its TTT diagram found in the required book by Callister's 10th edition, Chapter 10, page 325. * 5 puntos The minimum quench rate from 800°C to avoid pearlite transformation is O dT/dt = 400 °C/sec dT/dt = 357 °C/sec Ο Ο Ο O dT/dt = 508 °C/sec None of the options The time for austenite to transform to 50% bainite at 300°C is * 5 puntos t = 120 sec ОО t = 550 sec O t = 376 sec None of the options 5 puntos Initially quench a sample from 800°C to 500°C, hold the sample for 5 sec and then quench the sample to room temperature. The microstructure consists of O 75%B + 25%M 65%B+ 35%M 75%P + 25%B None of the options * 5 puntos Another sample is quenched from 800°C to 580°C and held there for 100 sec. Subsequently, the sample is transferred to another furnace at 400°C for 2 hours. Finally, the sample is quenched in boiling water. The microstructure consists of 100%P 100%B 100%M O None of the options 5 puntos A small sample containing 100%M is heat-treated at 800°C for 1 hour. Then, the sample is cooed at 200 °C/sec in oil. The final microstructure is O 100%A 100%B 100%M O None of the options