Johnston, B. G.

Osborn, C. J.

Scotchbrook, A.

Stout, R. D.

English

Lehigh University: Lehigh Preserve

Lehigh University
Lehigh Preserve
Fritz Laboratory Reports Civil and Environmental Engineering
1948
Comparison of three notch sensitivity tests.
C. J. Osborn
R. D. Stout
A. Scotchbrook
B. G. Johnston
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Recommended Citation
Osborn, C. J.; Stout, R. D.; Scotchbrook, A.; and Johnston, B. G., "Comparison of three notch sensitivity tests." (1948). Fritz
Laboratory Reports. Paper 1443.
http://preserve.lehigh.edu/engr-civil-environmental-fritz-lab-reports/1443

..
LEHIGH UNIVERSITY"
FRITZ LABORATORY
P. V. R. C. Fabricat:1cm Divlsion Project
Interim Report on: 12 February, ~94S
"Comparison of Three Notch Sensitivity' Tests ll
10 Introduction:
This report is written to acquaint members of the Fab-
rication Division of the P.V.R.C. with th~ results of the
comparison of three specified notch sensitivity tests perfonned
at Lehigh University at the request of the Fabrication Division
Meeting of September 10, 1947. The three tests investigated were:
(a) Lehigh slow notched bend test.
(b) Ship Structures Oommittee slow notched bend test. '
(c) Kahn tear test.
To assist the Division in appralslng these tests, observation~
concerning their convenience, cost, significance' B,nd' general suit-
ability will be included in this report in addition to the test
results.
II. Scope of Investigation:
The three tests under consideration were used to follow the
br.ittle temperature transition in the fol~owing materials:-
A-70 steel, 5/S11 pIa te: (a) as rolled
(b) after 10% tensile strain
(c) after 10% tensile strain
followed by aging at 200 for 2 hours.
A-70 steel, 1 1/4'1 plate, in these same three 'conditions"
a, b, and Co
A-20l steel, 5/S Il ~late, conditions a, b, and c.
A-20l steel, 1 1/4' plate, conditions a, b~ and c.
For each of these 12 materials, 24 specimens' were tested
over a range of temperatures, four at each temperature o
In order that the three tests could be cOTIlpared directly" all
criteria of ductility commonly measured in any of the tests were
measured in all three. This necessitated four or five diffe~ent
measurements for each test; viz. (1) The percentaLe of the·frac-
ture area which exhibited a brittle, cleavage type of failure. ~~
(2) '1'he energy a.bsorbed by the specimen after passing the maximum
load 'until the'.l.gad had:'fallem to half' the.'maximum..·. '
'(3,) The pgreeht~gecoht!rt-action ~n the width of the specimen at
a point 1/32 1' below the notch.
(4) The percentage contraction in width at the midpoint of the
specimen~
)(5) The bend angle or bend deflection at maximum load were
measured in the bend tests; the %elongation on a 2" gauge
length 1/4" below the notch was measured in the tear tests.
III. ~xperimental Procedure:
The tests were carried out in the usual manner, an autographic
load-defle cti on diagram. being obtained for each specimen. The
only modification of normal procedure was made in the Kahn tear
test, when lil·pins were used on the heavier 1 114 ft specimens in
place of the usual 3/4" pins~ -
A uniform procedure was adopted for plotting all results.
The arithmetic means of the four values ate ach temperature were
joined by straight lines, except for .som·e eases: where such a
method would produce a temperary and meaningless change in sign
of the slope within the transition scatter zone. In these cases
the points at each end of the inconsistent section were by-pasBed
and the straight lines drawn to the.midpoint of this, section. For
an example, see Fig. 5, as rolled.
IV. Res ult s:
All the results obtained are given in the figures attached
to thi s report and they have been sur,IDlarized in the three tables
of transition temperature. For .. these tables, the transition
temperature was taken as the temperature at which the curve had
fallen, with decreasing temperature to half its maximura value.
There were two exceptions to this practtce. In the energy vs.
temperature plots of the Lehigh bend results some of the curves
lacked points at temperatures sUfficiently high to ensure that a
maximum energy value had been reached~ in this case the transition
temperature was taken as that giving a prescribed energy leyel
(312.5 ft. Ibs). In the S.S.C. bend test and the Kahn tests vtlith
plots of bend deflection, %elongation and %contraction below
the notch, many curves did not fall to values of the order of half
their maximum even a t temperature s dovln·t 0 -gOoF. However, many··.·
of the curves (see for example Figs. 17 and 19) exhibited a sudClen
drop in the secriteria wi tb.in the ran6e of testing temperatures
and the transition temperatures quoted are the temperatures at a
mean between the upper and lower levels of this sudden drop.
V. Comparison of Tests:
In the early stages of this investigation the factors to be
considered in a choice of tests were listed and the following notes
are observations concerning these factors.
A. Convenience and Cost of the Test.
1. Hachining •. There is little to choose between the three
tests in-the matter of machining time but the Lehigh and Kahn
tests probably have an advantage over the S.S.C. test.
2. Testing rig o The Lehigh test set-up is the simplest
of the three, but both tho bend tests are much simpler than the
Kahn test. The latter is the only one in which regular replace-
ments of any parts-in this case the pins-are necessary.
)- 3 -
. '.
3. Ease and Speed of Testing. Here again the bend tests
show a definite superiority over the Kahn test, with the Lehigh
test somewhat quicker and more convenient than the S.S.C. test.
4. Size of Specimen. The S.S.C. test is considerably
more economical of material than the Kahn and Lehigh tests, the
latter usin£ slightly more than Kahn~
B~ ,drits~iori.Cho~en~
" ,~ Tfi~~itibJs criteria ofdUGtiliti0~ichw~re used in
this investii:,ation fall into tVJO classe~i;thof:le wJ;1ich can be re-
,garded as a measure of the energy required to initiate failure:
and those which are measures of the energy required to p~opagate
failure ~ Inth.e first class are bend, angle or bend deflect~on,
and %contraction below the notch; in the second class are %
brittle"in the fracture, %contraction at points removed from
the notch, and energy absorbed after maximmn load. A study of
the transition temperatures in Tables I, 2 and 3 will emphasize
this distinction.
Without discussing at this stage the relative import-
ance of these two types of criteria, it seems desiral)le to hav6J
measurements of at least one quantity from each class. This is
not diffic~lt because the %contraction below the notch and the
%brittle' in the frac ture are readily measured on any of the
thre~ tests investigated. '
. .lit this stage it might be mentioned that autographic
load deflection curves on thes~ :tests can only be obtained by
usinG the movement of the heads of the testing machine as a meas-
ure of the deformation in the specimen. Particularly in the S.S.C.
and Kahn tests, (using high loads and small deflections) this pro-
duces inaccuracies due to elastic deflection in the head of the
machine, which render themtographic load deflection curves very
difficult to interpret.
I. Transition Temperat~ As can be seen from the
curves included in this report there is little to choose between
the tests with respect to the temperature ranges in which the
transitions occur.
2. Scatter of Results. The curves and transition temper-
atures show firstly that the a.S.C. test and also the Kahn test
have a narrower transition range of temperatures than the Lehigh
test, at least in the case of the %brittle curves.
Also it shOUld be emphasized that for some reason not
yet apparent, the S.S.C. results conflict With the other tests in
! II / "that the I I 4 A-201 and 5 8" A-70 materials show a 10v'Jer trans-
ition temperature after straining - and sometimes even after
strain-aging - than in the as-rolled condition.·
D. Val!dity ofSamp]e.
The criticism has been leveled at the Lehigh s1~cimen that
). - 4 -
it does not test the full thickness of plate.
On the other hand, the other two tests can be criticized
because the specimen size is not standard and results vary con-
siderably with different plate thicknosses due to the change in
geometry of the spocimen o
E G Pre sent Extent of Use.
It is clearly undesirable to introduce a new test to this
field of testing unless such a test has marked advantages over
others at present in usee Actually none of tho three tests inves-
tigated is more generally accepted than the others.
I',
•
)
TABLE 1.
Transition Temperatures in of - ~ehJgh SJow Notched Bend Test
%Brittle Energy Bend Angle Jb Contraction
below notch
A-201, 5/8 n
as rolled 41 33 -88 -68
strained 45 43 -72 -44
strain-aged :t.01 95 -13 30
A-20], 1 1/-r.
as rolled 95 77 -78· -58
strained 123 95 -17 0
strain-aged 156 105 -21 32.
A-70, 5/8"
as rolled 100 85 -74 .-- -76
strained 123 143 5 37
strain-aged 177 197 -22. 15
~-70, 1 1/4 11
as rolled 162 103 -46 -42
)
strained 190 152: 12 45
strain-aged 183 138 30 60
. ~ •
TABLE ",z;.
Transition Temperatures in t)F - S.S.C. Slow Notched Bend Test
... ~ ,:. (.;
%
... J. " ..
Energy Bend %Contraction fa Contraction
Bri ttle Deflection at drill-hole at notch
A-2,21, 5/8 H
as-rolled -:-23 -15 -32 -11 -9
strained -19 -26 .-30 -13 -22
strain -aged -8 -13 - 7 ( ?) ~ 5 -13
A-2010Y411
as rolled 43 43 41 4.3 39
strained 22 21 18 26 14
strain-aged 43 40 27 47 27
A-70, 5/8"
as rolled 38 41 34 42 40
strained 16 17 7 16 7
strain-aged 53 55 53 58 60
A-70, 1 1/4 11
as rolled 97 98 89 92 53,
strained· 98 101 100 89 941:
strain-aged J 05 108 ? 105 103
•./ TABLE 3 •
'-
-----Transition Temperatures in of - Kahn Tear Test -
% Energy %Contraction %Contraction ElongatiC':'J.
Brittle below notch at Midpoint
A-20l, 5/8"
as rolled 28 14 ? 20 ?
strained 60 3·2 ? 55 ?
strgin-ag'ed 73 ?'(~\ 65 25
'J./;o . ~j
"-- -,-
A-201, 1 1/4 f1
as rolled 87, 57 ,50 87 60
'strained 102 93 86 100 90
strain-aged, 140 140 141 138 140
A';"70, 5/8" ,
as rolled 60 60 57 58 64
strained 88 85 85 85 85
"
strain-aged 103 83 105 95 110
A-70, 1 1/4'"
as rolled 145 156 134 125 142
strained 192 196 175 182 175
strain-aged 200 205 168 188 170
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Comparison of three notch sensitivity tests.

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Comparison of three notch sensitivity tests.

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