Question

MATERIAL SCIENCE

The six heat-treating cycles described below correspond to questions 32-37. Assume that these processes are used for identical samples of steel that have not been previously heat treated. Evaluate the results of each process according to how it alters the softness of the steel. Then, identify the process that results in the softest Structure of steel, followed by the process that results in the next-softest structure, and so on. Write the letter of your choice in the space provided. 18. Softest structure a. A sample of steel is heated to 19. Second-softest structure 1800°F and rapidly quenched 20. Third-softest structure to room temperature. The sam- ple is then reheated to 850°F, 21. Fourth-softest structure where it is held for one hour. 22. Fifth-softest structure Finally, it is rapidly quenched _23. Hardest structure back to room temperature, b. A sample of steel is heated to 1800°F and rapidly quenched until it reaches 550°F. The sample is then held at this tem- perature until a structural transformation to bainite occurs. Finally, it is rapidly quenched back to room temperature. A sample of steel is heated to 1800°F. It is then rapidly quenched to room temperature without undergoing any addi- tional heat treatment. d. A sample of steel is heated to 1800°F and rapidly quenched to room temperature. The sam- ple is then reheated to 1600°F in an oven. Finally, it is removed from the oven and allowed to cool in still air until it reaches room temperature. A sample of steel is heated to 1800°F and rapidly quenched to room temperature. The sam- ple is then reheated to 1700°F. It is held at 1700°F for several hours and is then slowly cooled in a temperature- controlled oven until it reaches room temperature. f. A sample of steel is heated to 1800°F and rapidly quenched to room temperature. The sam- ple is then reheated to 1100°F in an oven. It is held at this temperature for one hour and is then allowed to cool slowly to room temperature. e.

Answer 1

I have analyzed all the given description and then marked the following process according to their temperature variation and time duration.

d е Softest structure Second softest structure Third softest stoucture fowith softest structure fifth softent structure Hardest structure.

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