Mechanical Metallurgy Practice Test 5

1. The hardness value of martensite according to Mohr’s scale is ___________

2. The relationship between the flow stress and the strain rate is given in empirical form ______ where strain rate=ϒ, σ = flow stress, C & m = constant.

3. Which of the following hardness is least affected by surface scratched and local inhomogeneity of the material?

4. For the same long diagonal length of indenter of Vickers hardness and Knoop hardness, the Knoop hardness is how much percentage of the Vickers indenter?

5. The stress concentration and notch sensitivity are the same phenomena in the material.

6. The relationship between the stress and strain rate is given as σ=Cϒ^m, where m is strain rate sensitivity. The strain rate sensitivity _____________ with increase in temperature.

7. If the crosshead velocity of the machine is kept constant, the true strain rate of the sample will _________ with an increase in the length of the sample.

8. It is possible to have actual strain values more than one for some components and systems.

9. For the given specimen the necking will begin when the true strain is equal to __________

10. In which of the following sample, the diffuse necking will be observed?