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MSE 200
Test 2
Equations:
σ
=F/A, e=(llo)/lo, e=ln(l/lo), K=
σ
f
(
π
c)
1/2
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Q1. A sample of gage length 2 inches has received an elongation to 2.2 inches
in tension and compressed to 1.818 inches in compression. The engineering
stress is tension was 6 Mpsi and 6.2 Mpsi in compression. The area of cross
section initially is 2 square inches.
1. The true stress in tension is
a. 5.454 Mpsi b. 6.6 Mpsi c. 10 Mpsi (b )
2. The true stress in compression is
a. 5.636 Mpsi b. 6.6 Mpsi c. 10 Mpsi (a )
3. The true strains in both tension and compression are
a. not equivalent b. differ in magnitude c. equivalent (c )
4. The engineering strains in both tension and compression are
a. not equivalent b. differ in magnitude c. equivalent (b )
5. The area of cross section of the sample in tension is
a. 1.818 b. 2.2002 c. 4.4 (a )
6. The area of crosssection of the sample in compression is
a. 1.818 b. 2.2002 c. 4.4 (b )
Q2. A sample has been tested in plane strain fracture toughness test. A pre
crack of 1 cm lead to failure at a stress of 146.7 Mpa. A crack of twice the size
is introduced in another sample of the same alloy.
1. The fracture toughness of the alloy in units of Mpa (m)
1/2
is
a. 40 b. 2 c.26 (c )
2. The stress at which the sample fails with the new crack size is
a. 60.4 Mpa b. 140.2 Mpa c. 103.7 Mpa (c )
Q3. A sample has been subjected to steady state creep at a temperature of
600oC and the observed strain rate is 0.005 sec1. The same sample when
subjected to creep at 400oC showed a creep rate of 0.001 sec1.
1. The activation energy for creep (k is the Boltzmann's constant) in the
experiment is
a. 8219.2 k b. 4719.6 k c. 2223 k (b )
2. The temperature at which the creep is 0.0025 is
a. 456oC b. 501oC c. 804oC ( b)
Q4. In the given phase diagram below, label the phase diagram, apply the
phase rule and identify the invariant point points and the invariant reactions.
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 Spring '08
 wholedepartment
 Materials Science, Solubility, A., Fracture toughness

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