This
preview
has intentionally blurred sections.
Sign up to view the full version.
Unformatted text preview: 0
,7 $ 0' ”
UNIVERSITY OF CALIFORNIA AT BERKELEY DEPARTMENT OF CEE J ‘ SPRING SEMESTER, 2007 Instructor: PJ. M. Monteiro i , Name: _: i CE 60 — EXAMINATION
Please 'usti all our answers 496 g A
NE.“ N_fi+\‘
Question 1 (30 points) h g ; LIVKS; I I
1) Atomic packing factor (APF) is defined as:% 560% ~ 2 volume of atoms in unit cell / b a H a I: b ” 3 7X
APF =-—~——~“ ’ 2&1 g 3," volume of unit cell 2
Compute the atomic packing fac r for the BCC unit cell. (10 points) b“: a 1 : C4") 1
H 3 8X6?) ‘ll: am it s I? Kazl’ctz; (4“) arr-71
_?f C m zégwr‘ {so}: (“H257 a2,- (we. C 's .
“"2) In the absence of stress, the center togcgnter dist rice 0 t 3 6 atoms 15 0.248 nm - CL : H r
Under the tensile stress of 100 MPa along this direction, the atomic distance increases RTE/E
0.2489 nm, Calculate ggvmpdulus of elasticity (5 points) 2 .. :IGDHFQ
JfV‘AJ/uv: 0 [+8.21 p, 5 :0»69362‘40313E """ m. . . a—xI-w. . . 9' 3624
‘w 3) Does the elastlc modulus measure the resrstance of a materi to elastic or plastic} ” EW__ __<,,_ deformation? (5 points) ‘/_ if“. V 2. 75 x to" 4) A sample is tested and for a given load the true strain is equal to ln(1/5). Compute max—
englneering stram at this load. (5 pomts) 6T :— lm (is H) [Mo/i) : LA (654%) R 5) Stch can undergo two types of structural changes associated with phase changes. One is v
diffusive and the other is displacive. The formation of pearlite is an example of} U M transformation (5 points) /
> O / 6E +1 : C 1 “PM >7 W GZL‘: 3:: 7’23; my)
’7 W {—95 “J / \ W- Question 2 (30 points) I) Consider the stress-strain curve shown in Fig. l for a high—strength aluminum
alloy. a) Concentrate on Figure la which shows the initial portion of the stress-strain
curve. Use that diagram to determine the elastic modulus of the aluminum alloy.
Be sure to Show on Fig. la how you made the determination. (5 points) b) Determine the 0.2% offset Yield Point for the tested alloy/ Be sure to show on
Fig. l a how you made the determination (5 points) I c) Determine the ultimate tensile strength for the tested alloy. Be sure to show on Fig
lb how you made the determination. (5 points) d) Draw on Fig. 1b an approximate representation of the true stress-engineering
strain for the high strength alloy tested (5 points) e) Assume that the sample was loaded to 85,000 psi and then unloaded. Compute the
elastic recovery and the plastic deformation. Be sure to show on Fig lb how you
made the determination (10 points) v M 35”?”5 SW“
_ _ 90000 fl) 0') cV’W’
D. " D.
m“ 60000 . m”
3 5 60000
175 “:75
c» 40000 C)
.E E
8 $ 30000
.E 20000 .E
C” U)
.E x I UCJ
o .4, ,L M o J, , , ..
0.002 0.004 0.006 0.008 0.01 O 0.02 _0.04 .006 0.08 0.1
Engineering strain Engineering strain Flgla Fig. 1b :26. W, WM’ \ a- U7 _ 7"“‘995‘ : ixlo7P$I /’ b— g '2 .9 78 »~w——--~ Question 3: (40 points) 1) Suppose that you have a steel alloy with an unknown amount of carbon. Assume
that a sample has been heated to 950 C for two hours and now has been slowly
cooled to 720 C. On microscopic examination it is found that the steel has 20%
perlite and the remainder is proeutectoid ferrite. What is the Wei ght percent carbon in steel? (13 points)
11) A 0.95 percent C plain-carbon steel is slowly cooled from about 1000°C to a
temperature just slightly below 723°C. (at) Calculate the weight percent eutectic carbide present in the steel. (15 points)
(b) Calculate the weight percent perlite present in the steel. (12 points) IBM! 900 800 a 4m, om ; 723m Temperature r “C”;
‘1
E a
S (M be? 0.8 '
.45’
Weigle pemcntcmhon 3 “X
b 2 , : ,3’A
8 .5109. 1 Q'ézq /"‘
“ p ; WK ’ _______ w—A‘/’
; "1:22:70 4/) W “Va 3:0” E VO—fl— “My”!
W “AX/‘33:!)
M 0,13qgitfié
5767‘ '99.
- r675.‘ ~5L - ’5'
l ’_ w 0'92 5—5
W W 6’é7_rg Tyw ’ pin; : Euécctlc . pngéfi-fl'OIUY 0. NH : i ’ 2;) ...
View
Full Document
- Fall '05
- MONTEIRO
-
Click to edit the document details