|
IS0
INTERN AT I ON AL ORGAN I Z AT I ON FOR STAND A RD IZ AT I O N
IS0 RECOMMENDATION
.
R 375
TENSILE TESTING OF STEEL TUBES
1st EDITION
August 1964
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 1.50.
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.
---------------------- Page: 1 ----------------------
....
---------------------- Page: 2 ----------------------
BRIEF HISTORY
The IS0 Recommendation R 375, Tensile Testing of Steel Tubes, was drawn up by Technical
Committee ISO/TC 17, Steel, the Secretariat of which is held by the British Standards Institu-
tion (BSI).
Work on this question by the Technical Committee began in 1954 and led, in 1962, to the
adoption of a Draft IS0 Recommendation.
In November 1962, this Draft IS0 Recommendation (No. 519) was circulated to all the
IS0 Member Bodies for enquiry. It was approved, subject to a few modifications of an edi-
torial nature, by the following Member Bodies :
France Romania
Australia
Austria Hungary Spain
Belgium India Sweden
Brazil Ireland Switzerland
Burma Italy Turkey
United Kingdom
Canada Japan
Chile Netherlands U.S.A.
Czechoslovakia New Zealand U.S.S.R.
Denmark Norway Yugoslavia
Finland Poland
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 August 1964, to accept it as an IS0 RECOMMENDATION.
-3-
---------------------- Page: 3 ----------------------
ISO/R 375 - 1964 (E)
IS0 Recommendation R 375 August 1964
TENSILE TESTING OF STEEL TUBES
1. SCOPE
This IS0 Recommendation applies to tensile testing of complete steel tubes or longitudinal strips
of full thickness cut from steel tubes. The longitudinal strip test is not, however, usually carried
out on tubes less than 0.5 mm (0.02 in) thick.
Test pieces which are machined all over should be of the form described in the IS0 Recommen-
dation R 82, Tensile testing ofsteel, and should be tested in accordance with its requirements,
except that the rate of testing should be in accordance with clauses 7.1 and 7.2 of this IS0
Recommendation.
NOTE. - Test pieces, consisting of strips cut transversely from tubes, should be prepared and
treated in accordance with the material specification and then tested in accordance with the
requirements of IS0 Recommendations R 82 or R 86* according to whether the thickness is
equal to or less than 3 mm, except that the rate of testing should be in accordance with clauses 7.1
and 7.2 of this IS0 Recommendation.
For welded tubes, the position of the weld in relation to the test piece should be in accordance with
the material specification.
2. PRINCIPLE OF TEST
The test consists in subjecting a length of tube tested in full section, or a longitudinal strip of full
thickness cut from a tube, to an increasing tensile stress, generally to fracture, with a view to
determining one or more of the mechanical properties enumerated hereafter. The specification
for the product concerned should state which form of test piece is to be used.
The test is carried out at ambient temperature, unless otherwise specified.
3. DEFINITIONS
3.1 Gauge length. At any moment during the test, length 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 (L,,). Gauge length before the test piece is strained, and
(b) theJinal gauge length (Lu). Gauge length after the test piece has been fractured and
the fractures parts have been carefully fitted together so that they lie in a straight line.
* IS0 Recommendation R 82, Tensile testing ofsteel, and
IS0 Recommendation R 86, Tensile testing of’ steel sheet and strip less than 3 mm and not less than 0.5 mm thick.
-5-
---------------------- Page: 4 ----------------------
IÇO/R 375 - 1964 (E)
3.2
Percentage permanent elongation. Variation of the gauge length of a test piece subjected to
a prescribed stress (see clause 3.8) and, after removal of 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 L,-Lu, expressed as a percentage of the original gauge length L,.
3.4
Percentage reduction of’ area (Z). Ratio of the maximum change in cross-sectional area,
which has occurred during the test So-Su, to the original cross-sectional area So, expressed
as a percentage.
3.5 Maximum load (Fm). The highest load which the test piece withstands during the test.
3.6 Final load (Fu). Load imposed on the test piece at the moment of fracture.
3.7 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.
3.8 Stress (actually “nominal stress”). At any moment during the test, load divided by the
original cross-sectional area of the test piece.
3.9 Tensile strength (Rm). Maximum load divided by the original cross-sectional area of the
test piece, i.e. stress corresponding to the maximum load.
3.10 Yield stress (Re). Stress at yield point. If, in testing, a drop in the load is observed, the
stress corresponding to the highest load is known as the “upper yield point” and the stress
corresponding to the lowest load subsequently observed is known as the “lower yield point”.
3.10.1 In assessing the values of the upper and lower yield points, the characteristics 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.
3.11 Stress at permanent set limit (Ra). Stress at which, after removal of load, a prescribed per-
manent 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), p. 8).
3.11.1 The symbol used for this stress is supplemented by an index giving the prescribed per-
centage of the original gauge length, e.g. 0.2.
3.12 Proof strength (Re). 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), p. 8).
3.12.1 The symbol used for this stress is supplemented by an index giving the prescribed per-
centage of the original gauge length, e.g. O. 1.
-6-
---------------------- Page: 5 ----------------------
ISO/R 375 - 1964 (E)
4. SYMBOLS AND DESIGNATIONS
No. :*
Symbol Designation
1
External diameter of round tube, or, with tubes of other sec-
tions, diameter of the minimum circumscribing circle* *
2 Thickness of tube
3
Mean width of longitudinal strip
4
Original gauge length* * *
S
Parallel length
6
Total length
7
Gripped ends
8
Original cross-sectional area of the gauge length
9 Final gauge length
10 Minimum cross-sectional area of the gauge length after fracture
11 Permanent elongation after yield limit
12 Load at yield point
13 Yield stress
14
Maximum load
1s
Tensile strength
16 Final load, i.e. load at moment of fracture
17 Permanent elongation after fracture
18 Percentage elongation after fracture
Lu-L
x 100
LO
19 Percentage reduction of area after fracture
so - su
___
x 100
S
20 Stress at permanent set limit
21 Permanent set limit
22 Proof strength
23 Proof limit
* See Figures 1 to 5.
-7-
---------------------- Page: 6 ----------------------
ISO/R 375 - 1964 (E)
FIG. 1. - Test on full section
I n I
See Appendix A
FIG. 2. - Test on longitudinal strip
Load I
A
A
@@c" 12
. .-. ._
I
i I elongation
I
I
Stress i
-0
I
I
I
.-.---
Pencentoge
Pencentage
Elongation
Elmgotion
FIG. 4
FIG. 4
-8-
---------------------- Page: 7 ----------------------
œ
IÇO/R 375 - 1964 (E)
5. TEST PIECES
5.1 The test piece may consist of a piece of the tube tested in full section or a longitudinal strip
of full thickness cut from the tube.
Preferably the tube should be
...