ASTM D4145-10
(Test Method)Standard Test Method for Coating Flexibility of Prepainted Sheet
Standard Test Method for Coating Flexibility of Prepainted Sheet
SIGNIFICANCE AND USE
Organic coatings on precoated sheet are subjected to stresses when fabricated into products by roll forming, brake bending, or other deformation processes. These stresses can exceed the flexibility or adhesive strength of the coating, resulting in fracture of the coating which exposes the substrate, or in the loss of adhesion of the coating to the substrate. This test is a means of evaluating the ability of a coating system to withstand the stresses of fabrication.
The bend direction, whether the axis of bend is transverse to or along the rolling direction of the metal, and the temperature of the specimen when it is bent can affect the results of this test and should be agreed upon between the supplier and the user.
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 standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
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.
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Designation: D4145 − 10
Standard Test Method for
1
Coating Flexibility of Prepainted Sheet
This standard is issued under the fixed designation D4145; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Significance and Use
1.1 This test method describes a procedure for determining 4.1 Organic coatings on precoated sheet are subjected to
the flexibility and adhesion of organic coatings (paints) on stresses when fabricated into products by roll forming, brake
metallic substrates that are deformed by bending when the bending, or other deformation processes. These stresses can
sheet is fabricated into building panels or other products. exceed the flexibility or adhesive strength of the coating,
resultinginfractureofthecoatingwhichexposesthesubstrate,
1.2 The metal substrate must be capable of passing this test
or in the loss of adhesion of the coating to the substrate. This
without fracturing and with no excessive grain development.
test is a means of evaluating the ability of a coating system to
1.3 The values stated in inch-pound units are to be regarded
withstand the stresses of fabrication.
as standard. The values given in parentheses are mathematical
4.2 The bend direction, whether the axis of bend is trans-
conversions to SI units that are provided for information only
verse to or along the rolling direction of the metal, and the
and are not considered standard.
temperature of the specimen when it is bent can affect the
1.4 This standard does not purport to address all of the
results of this test and should be agreed upon between the
safety concerns, if any, associated with its use. It is the
supplier and the user.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5. Apparatus
bility of regulatory limitations prior to use.
5.1 A means of holding one end of the specimen rigidly
whilemakingthebendisneeded.Damagetothecoatingwhile
2. Terminology
making the bend must be avoided. Various bending tools such
2.1 Definitions of Terms Specific to This Standard:
as a vise with smooth jaws or with smooth inserts, a bend
2.1.1 T-bend, n—a description of the severity of a bend in
formingtool(Fig.2),abrakepress(Fig.3)oracombinationof
terms of the gauge or thickness (t) of the sheet to which the
tools have been found to be satisfactory.
coating has been applied; as used in this test method, the
5.2 IfthemetalisnotbentarounditselfasinFig.1,aseries
T-bend rating is the minimum number of thicknesses of metal
of bending dies with smoothly rounded ends may be used as
aroundwhichthecoatedsheetisbent(Fig.1),orifbentaround
guides around which the specimen is bent (Fig. 4).
a die, the number of thicknesses of metal equivalent to the
diameter of the die to achieve no fracture or removal of the
5.3 Bend Forming Tool.
coating.
5.3.1 A manual or automated operation forming tool ca-
pableoffacilitatingtheT-bendingofasamplemaybeused.An
3. Summary of Test Method
arbor press with an appropriate fixed V-shaped die and move-
3.1 Prepainted panels are bent 180° around progressively
able wedge has been found to be satisfactory for this purpose.
morethicknessesofmetalorlargerdiameterdies,theendpoint
5.4 Magnifier.
being when failures no longer occur. The panels may be
5.4.1 A magnifier capable of 5 to 10× magnification for
examined with or without low magnification (5 to 10×) after
examining the specimen for coating fracture and pickoff after
each bend in order to determine if the coating fractured
testing. A stereomicroscope has been found useful for this
(cracked). If loss of adhesion or pickoff is to be determined,
purpose.
this examination shall occur after performing a tape pull-off
test. 5.5 Clear Adhesive Tape.
6. Procedure
1
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of
6.1 Bending the Coated Specimen Around Itself:
Subcommittee D01.53 on Coil Coated Metal.
6.1.1 The coated specimen shall be at least 2 in. (50 mm)
Current edition approved June 1, 2010. Published August 2010. Originally
across the bend direction, by a length sufficient to make the
approved in 1983. Last previous edition approved in 2002 as D4145–83(2002).
DOI: 10.1520/D4145-10. requirednumberofbends.A2by6-in.(50by150-mm)sizeis
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D4145 − 10
FIG. 4 T-Bend Test Using a Die Around Which the Specimen is
Bent
selle
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:D4145–83(Reapproved2002) Designation:D4145–10
Standard Test Method for
1
Coating Flexibility of Prepainted Sheet
This standard is issued under the fixed designation D4145; 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 (´) indicates an editorial change since the last revision or reapproval.
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.
1.3The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information
only.
1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
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.
2. Terminology
2.1 Definitions of Terms Specific to This Standard:
2.1.1 T-bend, n—adescriptionoftheseverityofabendintermsofthegaugeorthickness(T)(t)ofthesheettowhichthecoating
has been applied; as used in this test method, the T-bend rating is the minimum number of thicknesses of metal around which the
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
achieve no fracture or removal of the coating.
3. Summary of Test Method
3.1Prepainted panels are bent 180° around progressively more thicknesses of metal or larger diameter dies, the end point being
when failures no longer occur.The panels are examined at low magnification (5 to 103) after each bend for fracture of the coating
(cracking) and, for loss of adhesion pickoff, by means of a tape pull-off test.
3.1 Prepainted panels are bent 180° around progressively more thicknesses of metal or larger diameter dies, the end point being
when failures no longer occur.The panels may be examined with or without low magnification (5 to 103) after each bend in order
to determine if the coating fractured (cracked). If loss of adhesion or pickoff is to be determined, this examination shall occur after
performing a tape pull-off test.
4. Significance and Use
4.1 Organic coatings on precoated sheet are subjected to stresses when fabricated into products by roll forming, brake bending,
or other deformation processes. These stresses can exceed the flexibility or adhesive strength of the coating, resulting in fracture
of the coating, exposing coating which exposes the substrate, or in the loss of adhesion of the coating to the substrate. This test
is a means of evaluating the ability of a coating system to withstand the stresses of fabrication.
4.2 The bend direction, whether the axis of bend is across transverse to or along the rolling diameterdirection of the metal, and
the temperature of the specimen when it is bent can affect the results of this test and should be agreed upon between the supplier
and the user.
5. Apparatus
5.1Ameans of holding one end of the specimen rigidly while making the bend is needed.Abench vise with smooth jaws or with
smooth inserts, preferably of a soft metal to avoid damage to the coating, has been found to be satisfactory.
1
This test method is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.53 on Coil Coated Metal.
Current edition approved May 10, 2002. Published May 2002. DOI: 10.1520/D4145-83R02.
Current edition approved June 1, 2010. Published August 2010. Originally approved in 1983. Last previous edition approved in 2002 as D 4145 - 83 (2002). DOI:
10.1520/D4145-10.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
D4145–10
NOTE 1—The above bends are expanded for clarity. They are actually
flat against themselves in the test.
FIG. 1 T-B
...
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