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IS0
FOR STAND AR D I ZAT I O N
I NT ERN AT1 ON AL ORGAN IZ AT I ON
IS0 RECOMMENDATION
R 203
INTERRUPTED CREEP TESTING OF STEEL
AT ELEVATED TEMPERATURES
(LOAD AND TEMPERATURE INTERRUPTED)
1 st ED IT1 ON
June 1961
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
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 203, Interrupted Creep Testing of Steel at Elevated Tempe-
ratures (Loud and Temperature Interrupted), was drawn up by Technical Committee lSO/TC 17,
Steel, the Secretariat of which is held by the British Standards Institution (B.S.I.).
Work on this matter, which was begun by the Technical Committee in 1955 was completed
in 1958, with the adoption of a proposal as a Draft IS0 Recommendation.
On 4 November 1959, the Draft IS0 Recommendation (No. 292) was distributed to all
the IS0 Member Bodies and was approved, subject to some editorial amendments, by the follow-
ing Iviember Bodies:
Australia France Poland
Austria Germany Portugal
Belgium Greece Romania
Brazil Hungary
Spain
Bulgaria India Sweden
Burma Israel Turkey
Chile Italy United Kingdom
Czechoslovakia Japan U.S.S.R.
Denmark Netherlands
Finland Norway
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council
which decided, in June 1961, to accept it as an IS0 RECOMMENDATION.
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ISO/R - 1981 (E)
IS0 Recommendation R 203 June 1961
INTERRUPTED CREEP TESTING OF STEEL
AT ELEVATED TEMPERATURES
(LOAD AND TEMPERATURE INTERRUPTED)
1. SCOPE
This IS0 Recommendation applies to those tests in which the strain is measured under tensile
creep stress and lies between 0.1 and 1.0 per cent, and in which the period of testing does not
exceed 10 O00 hours.*
It applies to tests in single machines and to each test in multiple testing machines.
2. PRINCIPLE OF TEST
The test consists of heating a test piece to a uniform temperature and subjecting it to constant
tensile load at that temperature, except that, during any interruptions, the load is removed and
the test piece returns to ambient temperature, and determining the strain as a function of time,
the measurement of elongation being carried out at ambient temperature after removal of load.
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,
Original gauge length (Lo). Gauge length measured at ambient temperature, before
applying the load.
3.2 Stress (actually “nominal stress”). At any moment during the test, load divided by the
original cross-sectional area of the test piece (at ambient temperature).
3.3 Percentage permanent elongation. Variation of the gauge length of a test piece, subjected to
a prescribed stress (see clause 3.2) and, after removal of same, expressed as a percentage of
the original gauge length.
This limit of 10 O00 hours is fixed as a function of the conditions of test, and in particular of the temperature limits in section 7. For tests
of more than 10 O00 hours, the tolerances should be agreed between the parties.
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6""-
ISO/R 203 - 1961 (E)
4. SYMBOLS AND DESIGNATIONS
~~
Number Symbol Designation
Diameter of a circular section test piece
Thickness of a flat bar
Width of a flat bar
Original gauge length measured at ambient temperature, before
of the load
application
Parallel length
Total length
Gripped ends
Original cross-sectional area of the gauge length
5.1 The cross-section of the test piece may be circular, square, rectangular or, in special cases,
of other form.
5.2 There should be transition curves between the gripped ends and the parallel length; the
gripped ends may be of any shape to suit the holders of the testing machine.
5.3 The tolerances on the preparation of the test pieces should be in accordance with those
given in the table, page 5.
5.4 As a rule, the diameter of the parallel length of machined cylindrical test pieces should be
not less than 4.0 mm (0.16 in).
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ISO/R 203 - 1961 (E)
TABLE
Tolerances on dimensions of test pieces
Tolerance on form
Machining tolerance*
Designation Nominal dimensions on nominal dimensions
(KA j 12) ~ ISA
Values
Symbols
Diameter of machined over 3 mm
& 0.06 mm 0.03 mm
to 6mm
circular-section test
piece
(metric units)
over 6 mm
+ 0.075 mm 0.04 mm
to 10mm
over 10 mm
i 0.09 mm 0.04 mm
to 18 mni
over 18 mm
& 0.105 mm 0.05 mm
to 30mm
~~
___
~~ ~
over 0.119 in
Diameter of machined
+ 0.002 5 in 0.001 in **
to 0.237 in
circular-section test
piece
(inch units) over 0.237 in
+ 0.003 in 0.001 in **
to 0.394 in
over 0.394 in
0.003 5 in 0.002 in **
to 0.709 in
over 0.709 in
& 0.004 in 0.002 in **
to 1.182in
~~
Dimensions of cross-
section of rectangular-
Same tolerances as for diameter of
section test piece,
circular-section test pieces
machined on the four
faces
Dimensions of cross- over 6 mm
0.22 mm
section of rectangular- to 10nim
section test piece,
unmachined on two
over 10 nim
0.27 mm
opposite faces
to 18 min
(metric units)
over 18 mm
0.33 mm
to 30 nini
over 30 mm
0.39 mm
to 50mm
Dimensions of cross-
over 0.237 in
0.009 in
section of rectangular-
to 0.394 in
section test piece,
unmachined on two
over 0.394 in
0.010 in
opposite faces
to 0.709 in
(inch units)
over 0.709 in
0.012 in
to 1.182 in
over 1.182 in
0.016 in
to 1.969 in
The machining tolerance applies when it is desired to use the nominal cross-section measurement or calculation.
** Rounded off to 0.001 in.
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ISO/R 203 - 1961 (E)
6. DETERMINATION OF ELONGATION
6.1 The measurement represents the str
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