This set of Basic Materials Science Questions and Answers focuses on “Continuous Cooling Transformation Diagrams”.
1. Continuous cooling transformation diagrams are mainly drawn for _________
c) Any alloy
Explanation: Continuous cooling transformation diagrams are drawn for mainly steels and steel of constant composition at a time is taken.
2. In continuous cooling transformation diagrams, which of the following is true?
a) The material is cooled rapidly
b) The material is first heated and then cooled rapidly
c) The material is cooled at a certain rate
d) The material is kept at a constant temperature
Explanation: In a continuous cooling transformation diagrams, the material is cooled at a certain rate instead of heating and then cooling it rapidly and then maintaining a constant temperature in case of TTT diagrams.
3. How many types of CCT diagram are there?
Explanation: There are two types of continuous cooling transformation diagrams which can be drawn. In the two type, some factors are changed to obtain a different curve.
4. Which physical property is normally measured to determine a CCT diagram?
b) Magnetic permeability
Explanation: CCT diagrams are determined by measuring magnetic permeability and specific volume during continuous cooling.
5. Slope change in a CCT diagram signify _________
a) Change in temperature
b) Change in pressure
c) Change in phase
d) Change in state
Explanation: When there is a slope change observed in a continuous cooling transformation diagram, it signifies that there is a change in phase occurring at that point.
6. Jominy end quench test is used for type 2 CCT diagram.
Explanation: The above statement is false. Jominy end quench test apart from its use in finding out hardenability of a material, it is also used for plotting type 1 CCT diagram.
7. Which of the following scientist gave a method to calculate the transformation temperature during continuous cooling?
Explanation: Scheil gave a method which can be used to calculate the transformation temperature of a material during continuous cooling of the material. The concept is called Scheil’s concept of fractional nucleation.
8. Critical cooling rate required is less in CCT than in TTT diagrams.
Explanation: The above statement is true. In a continuous cooling transformation diagrams, the critical cooling rate is less than that prescribed in TTT diagrams.
Sanfoundry Global Education & Learning Series – Materials Science.
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