ASTM D4145-83(1996)e1
(Test Method)Standard Test Method for Coating Flexibility of Prepainted Sheet
Standard Test Method for Coating Flexibility of Prepainted Sheet
SCOPE
1.1 This test method describes a procedure for determining the flexibility and adhesion of organic coatings (paints) on metallic substrates that are deformed by bending when the sheet is fabricated into building panels or other products.
1.2 The metal substrate must be capable of passing this test without fracturing and with no excessive grain development.
1.3 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
e1
Designation: D 4145 – 83 (Reapproved 1996)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Coating Flexibility of Prepainted Sheet
This standard is issued under the fixed designation D 4145; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Keywords and the unit of measurement statement were added editorially in January 1996.
1. Scope
1.1 This test method describes a procedure for determining
the flexibility and adhesion of organic coatings (paints) on
metallic substrates that are deformed by bending when the
sheet is fabricated into building panels or other products.
1.2 The metal substrate must be capable of passing this test
without fracturing and with no excessive grain development.
1.3 The values stated in inch-pound units are to be regarded
as the standard. The values given in parentheses are for
information only.
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
2. Terminology
2.1 Definitions of Terms Specific to This Standard:
2.1.1 T-bend—a description of the severity of a bend in
terms of the thickness (T) of the sheet to which the coating has
NOTE 1—The above bends are expanded for clarity. They are actually
been applied; as used in this test method, the T-bend rating is flat against themselves in the test.
FIG. 1 T-Bend Test in Which the Coated Specimen is Bent
the minimum number of thicknesses of metal around which the
Around Itself
coated sheet is bent (Fig. 1), or if bent around a die, the number
of thicknesses of metal equivalent to the diameter of the die to
resulting in fracture of the coating, exposing the substrate, or
achieve no fracture or removal of the coating.
loss of adhesion to the substrate. This test is a means of
evaluating the ability of a coating system to withstand the
3. Summary of Test Method
stresses of fabrication.
3.1 Prepainted panels are bent 180° around progressively
4.2 The bend direction, whether the axis of bend is across or
more thicknesses of metal or larger diameter dies, the end point
along the rolling diameter of the metal, and the temperature of
being when failures no longer occur. The panels are examined
the specimen when it is bent affect the results of this test and
at low magnification (5 to 103) after each bend for fracture of
should be agreed upon between the supplier and the user.
the coating (cracking) and, for loss of adhesion pickoff, by
means of a tape pull-off test.
5. Apparatus
5.1 A means of holding one end of the specimen rigidly
4. Significance and Use
while making the bend is needed. A bench vise with smooth
4.1 Organic coatings on precoated sheet are subjected to
jaws or with smooth inserts, preferably of a soft metal to avoid
stresses when fabricated into products by roll forming, brake
damage to the coating, has been found to be satisfactory.
bending, or other deformation processes. These stresses can
5.2 If the metal is not bent around itself as in Fig. 1, a series
exceed the flexibility or adhesive strength of the coating,
of bending dies with smoothly rounded ends may be used as
guides around which the specimen is bent (Fig. 2).
This test method is under the jurisdiction of ASTM Committee D-1 on Paint
and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.53 on Factory-Precoated Strip Metal. Scotch Brand #610 tape manufactured by 3M Co., St. Paul, MN or equivalent,
Current edition approved March 25, 1983. Published July 1983. or as agreed upon between the supplier and the user.
D 4145
6.1.3 Continue to bend the specimen until the bent end can
be inserted in the jaws of the vise. Tighten the vise to complete
the 180° bend, which is called an OT bend. Take care to tighten
the vise sufficiently so that the apex of the bend is as flat as can
be reasonably achieved.
6.1.4 Examine the bend using a hand lens or low-power
microscope for cracks in the coating.
6.1.5 Apply pressure-sensitive tape along the bend. Rub
the tape flat; then, holding the specimen firmly, remove the tape
with a rapid movement at an angle of 180° to the bend surface.
Examine the tape for coating removed from the surface of the
specimen (that is, pickoff). In the case of a coated steel
specimen (for example,
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.