ASTM B571-97(R2008)

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ASTM B571-97(R2008)1.1 This practice covers simple， qualitative tests for evalu-ating the adhesion of metallic coatings on various substances.
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
standard.
1.3This 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. Significance and Use
2.1 These tests are useful for production control and for
acceptance testing of products.
2.2 Interpreting the results of qualitative methods for deter-mining the adhesion of metallic coatings is often a controver-sial subject. If more than one test is used， failure to pass any
one test is considered unsatisfactory. In many instances， the
end use of the coated article or its method of fabrication will
suggest the technique that best represents functional require-ments. For example， an article that is to be subsequently
formed would suggest a draw or a bend test; an article that is
to be soldered or otherwise exposed to heat would suggest a
heat-quench test. If a part requires baking or heat treating after
plating， adhesion tests should be carried out after such post-treatment as well.
2.3 Several of the tests are limited to specific types of
coatings， thickness ranges， ductilities， or compositions of the
substrate. These limitations are noted generally in the test
descriptions and are summarized inTable 1for certain metallic
coatings.
2.4 Perfect” adhesion exists if the bonding between the
coating and the substrate is greater than the cohesive strength
of either. Such adhesion is usually obtained if good electro-plating practices are followed.
2.5 For many purposes， the adhesion test has the objective
of detecting any adhesion less than perfect.” For such a test，
one uses any means available to attempt to separate the coating
from the substrate. This may be prying， hammering， bending，
beating， heating， sawing， grinding， pulling， scribing， chiseling，
or a combination of such treatments. If the coating peels，
flakes， or lifts from the substrate， the adhesion is less than
perfect.
2.6 If evaluation of adhesion is required， it may be desirable
to use one or more of the following tests. These tests have
varying degrees of severity; and one might serve to distinguish
between satisfactory and unsatisfactory adhesion in a specific
application. The choice for each situation must be determined.
2.7 When this guideline is used for acceptance inspection，
the method or methods to be used must be specified. Because
the results of tests in cases of marginal adhesion are subject to
interpretation， agreement shall be reached on what is accept-able.
2.8 If the size and shape of the item to be tested precludes
use of the designated test， equivalent test panels may be
appropriate. If permitted， test panels shall be of the same
material and have the same surface finish as the item to be
tested and shall be processed through the same preplating，
electroplating， and postplating cycle with the parts they repre-sent.
3. Bend Tests
3.1 Bend the part with the coated surface away over a
mandrel until its two legs are parallel. The mandrel diameter
should be four times the thickness of the sample. Examine the
deformed area visually under low magnification， for example，
43， for peeling or flaking of the coating from the substrate，
which is evidence of poor adhesion. If the coating fractures or
blisters， a sharp blade may be used to attempt to lift off the
coating. With hard or brittle coatings， crackin