# Mechanical Behaviour Questions and Answers – Transition Temperature and Its Significance

This set of Mechanical Behaviour Multiple Choice Questions & Answers focuses on “Transition Temperature and Its Significance”.

1. Which factor affects ductile brittle transition behaviour the most?
a) Strain rate
b) Temperature
c) Triaxiality
d) Notching

Explanation: Temperature is the most important factor among others. The temperature at which this behaviour changes sharply, is called ductile brittle transition temperature.

2. With an increase in sharpness of notch, transition temperature ________
a) Increases
b) Decreases
c) Remains constant
d) First increases then decrease

Explanation: Sharper the notch, the higher will be the transition temperature. Transition temperature varies slightly with a sharpness of notch.

3. Which test is used for DBTT?
a) Tensile test
b) Charpy test
c) Fatigue test
d) Leeb test

Explanation: DBTT is determined by impact test. A notch is made in specimen. These are the Charpy test and Izod test.

4. The energy absorbed in fracture due to impact is known as _________
a) Static energy
b) Toughness
c) Fracture energy
d) Transition energy

Explanation: The energy absorbed in fracture due to impact is known as fracture energy. It is shown as Cv. It is determined by fracture appearance.

5. In which mode, the fracture surface appears to be bright and granular?
a) Dynamic mode
b) Static mode
c) Ductile mode
d) Brittle mode

Explanation: Fracture surface appears bright and granular in a brittle mode. It appears dull and fibrous for ductile fracture.
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6. Which region is known as the initiator of brittle fracture?
a) High triaxial stress
b) Tensile stresses
c) Vacancies
d) Shear stress

Explanation: Brittle fracture initiate in a region of high triaxial stresses existing. It is in the vicinity of root of notch.

7. Above which temperature, fracture changes to almost totally ductile from substantially brittle?
a) FTP
b) NDT
c) DBTT
d) LSE

Explanation: Above FTP temperature, fracture changes to almost totally ductile from substantially brittle. FTP stands for fracture transition plastic. Problem of brittle fracture is negligible above this.

8. Below which temperature, a material in particular a steel plate breaks?
a) FTP
b) NDT
c) DBTT
d) LSE

Explanation: Below NDT temperature, a material in particular a steel plate breaks. NDT stands for nil ductility temperature. Material does not break on temperature higher than NDT.

9. What is the region between the lower shelf and the upper shelf?
a) Transition
b) Tension
c) Fracture
d) Cleavage

Explanation: The region between the lower and upper shelf is known as the transition region. It is difficult to clearly determine a specific transition temperature.

10. Ductile to brittle transition temperature is known as ________
a) Upper shelf energy
b) Fracture transition plastic
c) Nil ductility temperature
d) Fracture appearance transition temperature

Explanation: Ductile to brittle transition temperature is also known as fracture appearance. The absorbed energy is an average of USE and LSE values. NDT is lower than DBTT.

11. FTP is always lower than DBTT.
a) True
b) False

Explanation: DBTT is where 50% brittle and 50% ductile fracture is observed. Above FTP fracture is observed ductile. So FTP is higher than DBTT.

12. DBTT is a great concern in steels.
a) True
b) False

Explanation: Most of the steel is BCC structure. These have slip systems based on temperature. So DBTT is of great concern.

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