TESTS ON METALS
DETERMINATION OF
FORMABILITY INDICES
normazione
PROCUREMENT
SPECIFICATION
50116
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E.D. -- Ingegneria dei Materiali
MANAGER Department
E.D. -- Ingegneria dei Materiali
Code
SUPERVISOR Department
TMD
Date: 08/23/2005
1
Ch.
GENERAL
Purpose
This Standard covers the procedure for measuring anisotropy and work hardening indices of
metal sheet and strip.
Date
Description
12/22/80, Edition 2 --- Revised.
08/23/05
(FD)
CONFIDENTIAL
THIS DOCUMENT MUST NOT BE PRODUCED OR CIRCULATED TO THE THIRD PARTIES
Edition 3 -- Supervisor and Manager deparment added .
PUBLISHED BY SATIZ S.p.A. NORMAZIONE
WITHOUT PRIOR WRITTEN CONSENT BY FIAT AUTO S.P.A. IN CASE OF DISPUTE
THE ONLY VALID REFERENCE IS THE ORIGINAL ITALIAN EDITION
Change
Edition
1.1
50116
Page
Change
1.2
Scope
This Standard applies to metals sheet and strip intended for the manufacture of stamped parts.
2
PRINCIPLE
Test consists of submitting a test piece to a tensile load so as to determine plastic strain during
stamping.
3
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WITHOUT PRIOR WRITTEN CONSENT BY FIAT AUTO S.P.A. IN CASE OF DISPUTE
THE ONLY VALID REFERENCE IS THE ORIGINAL ITALIAN EDITION
SYMBOLS AND DEFINITIONS
Symbols and definitions to be applied are shown in Figure 1 and in Table 1.
Fig. 1 TENSILE TEST PIECES
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50116
Table 1 Symbols and definitions
References
No.
Symbol
ao
Thickness of test piece (before testing)
au
Thickness of test piece (after testing)
bo
Width of test piece (before testing)
bu
Width of test piece (after testing)
Lo
Gage length (before testing)
Lu
Gage length (after testing)
Lc
Parallel length
Lt
Overall length
L1
L2
A
Gage lengths corresponding to further plastic deformation
A=ln
L2
L1
L2
ln
B
L1
B=ln
L1
ln
L0
Total load
Work hardening index
Average value of work hardening index
ln
Natural logarithm
Anisotropy index
Average value of standard plastic anisotropy
r
r0 ; n0
Average value of planar plastic anisotropy
r n measured in rolling direction
r45 ; n45
r n measured at 45 to rolling direction
r90 ; n90
r n measured at right angles to rolling direction
4
APPARATUS
Apparatus is that for tensile test. See Std. 50113.
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Definition
50116
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Change
5
TEST PIECES AND TEST CONDITIONS
See Std. 50113 and 50215.
6
PROCEDURE
Carry out a tensile test as per Std. 50113, obtaining a stress/strain curve similar to that shown
in fig. 2.
Fig. 2
F mass
Load/deformation
curve
Deformation
(Elongation)
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THE ONLY VALID REFERENCE IS THE ORIGINAL ITALIAN EDITION
6.1
Anisotropy index
Test consists of submitting a test piece to a tensile load and interrupting the test at 20%
elongation before reduction in area occurs (F mass in fig. 2).
To calcolate r apply the followingformula:
bo
ln
r=
ln
bu
Lu
Lo
ln
bo
bu
Should test piece pass through stage of area reduction before reaching 20% elongation, repeat
test selecting a value less than uniform elongation as final elongation.
6.1.1
Measurements
To take required measurements use measuring instruments graduated in 0,01 mm. Estimate to 0,005
mm and round off to the nearest value.
Measuring instruments shall be fitted with flat tracers. Care must be taken to measure surfaces with
lengths of contact less than or equal to 3 mm.
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50116
6.1.1.1
Gage width (b o ; b u )
Take two measurements of overall width for each test piece at evenly spaced points:
along gage length (Lo ) before deformation;
along gage length (Lu ) after deformation.
6.1.1.2
Gage length (Lo ; Lu )
When measuring the length it is sufficient to take one measurement only of the gage length
between reference points along the longitudinal axis of the test piece, both before and after test
piece has been submitted to plastic strain.
6.1.2
Speed of test
For speed of test see Std. 50113..
6.1.3
Camber of test pieces
Unless otherwise agreed, after testing camber shall be less than:
0,22 mm for test pieces with bo = 20 mm
0,18 mm for test pieces with bo = 12,5 mm
6.2
Work hardening index
Proceed as follows:
1) Submit the test piece to a tension load with a plastic deformation speed not greater than
0,5 cm per minute.
Should test piece pass through area reduction phase before reaching 18% elongation,
repeat test selecting a value less than uniform elongation for final elongation.
3)
Value n for a given direction relative to that of rolling is calculated on the basis of the
following formula:
n=
(lnF 2 ln F 1) + A
B
6.2.1
Speed of test
For speed of test see Std. 50113.
PUBLISHED BY SATIZ S.p.A. NORMAZIONE
WITHOUT PRIOR WRITTEN CONSENT BY FIAT AUTO S.P.A. IN CASE OF DISPUTE
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Since plastic strain above is to be measured to within a tolerance of 0,05 mm, a strain gage
fitted with a 15 mm amplitude dial gage and adjusted for necessary gage length with
tolerance of 0,05 mm shall be used.
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2) Measure to a max. approximation of 0,5 kg the loads for 10% and 18% plastic deformation
under load. For test piece A 50 with Lo = 50 m said deformations correspond to a deformed
gage length of 55 and 59 mm respectively, and for A 80 test piece with Lo = 80 mm of 88 and
94,4 mm respectively.
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50116
Change
6.2.2
Camber of test pieces
See para. 6.1.3 of this Standard.
7
EXPRESSION OF RESULTS
Values of r and of n depend on direction of preparation of test piece relative to direction of rolling.
Measurement according to different direction of preparation makes it possible to calculate:
average value of standard plastic anisotropy (r)
average value of planar plastic anisotropy ( r )
average value of work hardening index (n)
These valdes are defined as follows:
r=
r 0 + 2r 45 + r 90
4
r =
n=
CONFIDENTIAL
THIS DOCUMENT MUST NOT BE PRODUCED OR CIRCULATED TO THE THIRD PARTIES
WITHOUT PRIOR WRITTEN CONSENT BY FIAT AUTO S.P.A. IN CASE OF DISPUTE
THE ONLY VALID REFERENCE IS THE ORIGINAL ITALIAN EDITION
When calculating
r 0 2r 45 + r 90
2
n 0 + 2n 45 + n 90
4
(r) and r refer to test pieces submitted to the same plastic deformation.
REFERENCES
50113 50215.
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