BE 1300
Exam 3, November 23, 2010
1
Exam 3
BE 1300 Materials Science for Engineering
11:45AM to 1:05PM
NAME
____________________
ID#
_______________
Quiz Section (Time, Day, and TA's name):
______________________________________________
CLOSED BOOK/CLOSED NOTES:
Nothing except this exam, your calculator (devoid of programmed
equations) and a pen may be on your desk or in your line-of-sight
at any time.
Do not use pencils.
Scratch work may be done on the
reverse sides of this exam or on the two blank sheets.
However,
credit for any problem at those locations that you want graded
will not be given unless you tell us, at the original problem, where
it is.
College policy states that anyone giving or receiving
information during an exam will be given an immediate failing
grade for the course.
I understand and agree to abide by the above rules.
SIGNATURE: ___________________________________
NO EXAM WILL BE GRADED WITHOUT A SIGNATURE
.
Scores
Problem One
_______
Problem Two
_______
Problem Three _______
Problem Four
_______
Problem Five
_______
TOTAL
_______

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BE 1300
Exam 3, November 23, 2010
2
You may need the some of following information and formulas:
Boltzmann’s constant
k
= 8.62
10
-5
eV/(atom K).
Gas constant
R
= 8.314 J/mol-K.
Avogadro’s number
N
A
= 6.023
10
23
atoms/mol.
Stress:
σ
=
F/A
Relaxation Modulus:
E
r
(t)
=
σ
(t)/
ε
0
Strain:
ε
=
(
L - L
0
) /
L
0
Hall-Petch equation:
σ
y
=
σ
0
+
k
y
/d
½
Hooke’s Law:
σ
=
E
ε
Poisson’s ratio:
ν
= -
ε
x
/
ε
z
= -
ε
y
/
ε
z
Flexural strength for rod geometry:
σ
fs
= F
f
L/
(
π
R
3
)
Do all of the Problems: Each one is worth 20 points.
Problem One --
Circle the correct answer to each question.
There is only one correct answer to each question!
This problem
is graded on answer only.
1. Strain hardening or cold work
a) Increases the yield strength and ductility of alloys.
b) Increases the yield strength and decreases the ductility of
alloys.
c) Decreases the yield strength and increases the ductility of
alloys.
d) Decreases the tensile strength and increases the ductility of
alloys.