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Ref.No.: ISO/R82-1@59(E)
IS0
I NT E R N AT1 O N A L ORGAN I ZATl O N FOR
STAN DARD I Z AT I O N
IS0 RECOMMENDATION
R 82
TENSILE TESTING OF STEEL
1st EDITION
February 1959
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Copies to be obtained through the national standards organizations.
Also issued in French and Russian.
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BRIEF HISTORY
The IS0 Recommendation R 82, Tensile Testing of Sfeel, was drawn up
by Technical Committee ISO/TC 17, Sfeel, the Secretariat of which is held by
the British Standards Institution (B.S.I.).
At the first meeting of ISO/TC 17, held in London, in June 1950, the Secre-
tariat submitted a first draft proposal for the tensile test, based on a document
which had been drawn up by the former International Federation of the National
Standardizing Associations (ISA).
The Technical Committee discussed this draft proposal in meeting, and
instructed its Working Group No. 1, Methods of Mechanical Testing for Sled,
to prepare a new version of it, taking into account the views expressed at the
first meeting.
In August 1953, the Working Group submitted a second draft proposal,
which was studied by the Technical Committee during its third plenary meeting,
held in London, in December 1953. The ISO/TC 17 Secretariat was then assigned
to draw up a third draft proposal, incorporating the changes voted during the
meeting, and this was circulated in April 1954.
The comments of the Member Bodies on this third draft proposal were
in Stockholm, in June 1955, and the
discussed at the fourth plenary meeting, held
Technical Committee decided to adopt it, subject to a few amendments, as a
Draft IS0 Recommendation.
On 31 October 1956, this Draft IS0 Recommendation (No. 133) was dis-
tributed to all the IS0 Member Bodies and was approved, subject to a few modi-
fications of details, by the following Member Bodies :
Sweden
*Canada Japan
Denmark Netherlands Turkey
France Pakistan *Union of
Poland South Africa
*Greece
Hungary Portugal U.S.S.R.
Spain Yugoslavia
*Ireland
One Member Body opposed the approval of the Draft: Germany
The Draft IS0 Recommendation was then submitted by correspondence
to the IS0 Council, which decided, in February 1959, to accept it as an
IS0 RECOMMENDATION.
These Member Bodies stated that they had no objection to the Draft being approved.
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ISO/R82-1959(E)
I SO Reco m men dati o n R 82
February 1959
TENSILE TESTING OF STEEL
1. SCOPE
This IS0 Recommendation applies to products of diameters equal to or greater
than 4 mm (0.157 in) or thicknesses equal to or greater than 3 mm (0.118 in).
For the tensile testing of certain products, such as sheets, strips, wires and
tubes, particular specifications are applicable.
2. PRINCIPLE OF TEST
The test consists in subjecting a test piece to tensile stress, generally to fracture,
with a view to determining one or more of the mechanical properties enumerated
hereafter. The test is carried out at ambient temperature, unless otherwise
specified.
3. DEFINITIONS
3.1 Gauge length. At any moment during the test, the prescribed part of the
cylindrical or prismatic portion of the test piece on which elongation is measured.
In particular, a distinction should be made between the following:
(a) the original gauge length (Lo). Gauge length before the test piece is
strained, and
(b) the final gauge length (Lu). Gauge length after the test piece has been
fractured and the fractured parts have been carefully fitted together so
that they lie in a straight line.
3.2 Percentage permanenf elongation. Variation of the gauge length of a test
a prescribed stress (see clause 3.9) and, after removal of
piece subjected to
same, expressed as a percentage of the original gauge length. The symbol of
this elongation is supplemented by an index indicating the prescribed stress.
3.3 Percentage elongation after fracture (A). Permanent elongation of the
gauge length after fracture Lu-Lo, expressed as a percentage of the original
gauge length Lo.
3.4 Percentage reduction of area (Z). Ratio of the maximum change in cross-
sectional area, which has occured during the test S,-S,, to the original cross
sectional area So, expressed as a percentage.
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ISO/R 82 - 1959 (E)
3.5 Percentage elongation factor at point of constriction (Zu). Ratio of the
maximum change in cross-sectional area, which has occurred during the test
S,-S,, to the minimum cross-sectional area after fracture Su, expressed as
a percentage.
3.6 Maximum load (F,,,). The highest load which the test piece withstands
during the test.
3.7 Final load (Fu). Load imposed on the test piece at the moment of fracture.
3.8 Load at yield point (Fe). Load at which the elongation of the test piece
first increases without increase of load or with decrease of load.
3.9 Stress (actually << nominal stress ”). At any moment during the test,
load divided by the original cross-sectional area of the test piece.
3.10 Tensile strength (I?,,,). Maximum load divided by the original cross-
sectional area of the test piece, i.e. stress corresponding to the maximum
load.
If, in testing, a drop in the load
3.11 Yield stress (Re). Stress at yield point.
is observed, the stress corresponding to the highest load is known as the
<< upper yield point” and the stress corresponding to the lowest load sub-
‘< lower yield point ”.
sequently observed is known as the
3.11.1 In assessing the values of the upper and lower yield points, the charac-
teristics of the testing machine should be taken into consideration; for example,
the inertia of the dynamometer of the testing machine may result in the load
dropping below the true lower yield point.
3.12 Stress at permanent set limit. Stress at which, after removal of load, a
prescribed permanent elongation, expressed as a percentage of the original
gauge length, occurs; the prescribed value may frequently be 0.2 per cent
(see Fig. 4 (a), page 7).
3.12.1 The symbol used for this stress is supplemented by an index giving
the prescribed percentage of the original gauge length, e.g. 0.5.
3.13 Stress at proof limit. Stress at which a non-proportional elongation,
equal to a specified percentage of the original gauge length, occurs. When
a stress at proof limit is specified, the non-proportional elongation should be
stated, e.g., proof limit 0.1 per cent or 0.2 per cent (see Fig. 4 (b), page 7).
3.13.1 The symbol used for this stress is supplemented by an index giving
the prescribed percentage of the original gauge length, e.g. 0.1.
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ISO/R 82- 1959 (E)
4. SYMBOLS AND DESIGNATIONS
Number Symbol
Designation
.
1 d
Diameter of the round part of a round bar, or,
with other sections, diameter of the minimum
circumscribing circle *
2 a Thickness of a flat bar
3 b
Width of a flat bar
4 Lo **
Original gauge length
5
Parallel length
Lc
6
Total length
Lt
7 Gripped ends
8 Original cross-sectional area of the gauge length
9 Final gauge length
10 Minimum cross-sectional area after fracture
11 Load at yield point
12
Yield stress
Re
13 Maximum load
'Fin
14
Tensile strength
'I 5 2 ** Final load, i.e. load at moment of fracture
16 Permanent elongation after fracture
Lu -Lo
17 A Pepcentage elongation after fracture
Lu - Lo
LO
so-su
Z Percentage reduction of area ~
18
SO
19 Percentage elongation factor at point of con-
ZU
striction
so-su x 100
SU
20 Stress at permanent set limit
Permanent set limit
21
22 Stress at proof limit
Proof limit
23
The minimum circumscribing circle is the smallest circle which completely circumscribes the whole perl-
of the cross-section, but it need not pass through more than two points.
phery
**
In corres ondence and where no misunderstanding is possible. the symbols Lo and R, may be replaced
by L anrfR respectively.
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ISO/R 82- 1959 (E)
FIG. 1
FIG. 2
Note: The form of end of test piece as shown is only intended as O guide.
I
I
I
I
1.-
C ~ 4 Elongation
FIG. 3
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ISO/R 82 - 1959 (E)
I
l
I
I
Stress!
1/--
1 I
I
I
I
I
I
.-.-.-.-
Percentage Percen toge
e longat ion
elongation
FIG. 4 (a) FIG. 4 (b)
5. TEST PIECES
5.1 The cross-section of the test piece may be circular, square, rectangular
or, in special cases, of other form. For test pieces of rectangular section, it
is recommended that a ratio of 4:l for sides should not be exceeded.
5.1.1 There is a transition curve between the gripped heads and the parallel
length; and the gripped heads may be of any shape to suit the holders of the
testing machine. Sections, bars, etc., may be tested without being machined.
5.1.2 The tolerances on the preparation of the test pieces are in accordance
with those given in the table, page 8.
5.2 As a rule, the diameter of the calibrated portion of the machined cylin-
drical test pieces is not less than 4.0 mm (0.16 in).
5.3 As a rule, only test pieces complying with the requirement that
L, = “X, where k may be equal to 4, 5.65, 8.16 or 11.3, are used for the
tensile test; these test pieces are known as proportional test pieces.
5.3.1 The international use of proportional test pieces with lc = 4, 8.16 and
...