ASTM B636-84(2010)
(Test Method)Standard Test Method for Measurement of Internal Stress of Plated Metallic Coatings with the Spiral Contractometer
Standard Test Method for Measurement of Internal Stress of Plated Metallic Coatings with the Spiral Contractometer
SIGNIFICANCE AND USE
The spiral contractometer, properly used, will give reproducible results (see 8.5) over a wide range of stress values. Internal stress limits with this method can be specified for use by both the purchaser and the producer of plated or electroformed parts.
Plating with large tensile stresses will reduce the fatigue strength of a product made from high-strength steel. Maximum stress limits can be specified to minimize this. Other properties affected by stress include corrosion resistance, dimensional stability, cracking, and peeling.
In control of electroforming solutions, the effects of stress are more widely recognized, and the control of stress is usually necessary to obtain a usable electroform. Internal stress limits can be determined and specified for production control.
Internal stress values obtained by the spiral contractometer do not necessarily reflect the internal stress values found on a part plated in the same solution. Internal stress varies with many factors, such as coating thickness, preparation of substrate, current density, and temperature, as well as the solution composition. Closer correlation is achieved when the test conditions match those used to coat the part.
SCOPE
1.1 This test method covers the use of the spiral contractometer for measuring the internal stress of metallic coatings as produced from plating solutions on a helical cathode. The test method can be used with electrolytic and autocatalytic deposits.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.3 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: B636 − 84(Reapproved 2010)
Standard Test Method for
Measurement of Internal Stress of Plated Metallic Coatings
1
with the Spiral Contractometer
This standard is issued under the fixed designation B636; 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 magnify the movement of the helix.As the helix is plated, the
stress in the deposit causes the helix to wind more tightly or to
1.1 This test method covers the use of the spiral contracto-
unwind, depending on whether the stress is compressive (−) or
meter for measuring the internal stress of metallic coatings as
tensile (+). From the amount of needle deflection and other
produced from plating solutions on a helical cathode. The test
data, the internal stress is calculated.
method can be used with electrolytic and autocatalytic depos-
its. 3.2 With instrument modifications, the movement of the
helixcanbemeasuredelectronicallyinsteadofmechanicallyas
1.2 The values stated in either SI units or inch-pound units
described in 3.1.
are to be regarded separately as standard. The values stated in
each system may not be exact equivalents; therefore, each
4. Significance and Use
system shall be used independently of the other. Combining
4.1 The spiral contractometer, properly used, will give
values from the two systems may result in non-conformance
reproducible results (see 8.5) over a wide range of stress
with the standard.
values. Internal stress limits with this method can be specified
1.3 This standard does not purport to address all of the
for use by both the purchaser and the producer of plated or
safety concerns, if any, associated with its use. It is the
electroformed parts.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- 4.2 Platingwithlargetensilestresseswillreducethefatigue
strengthofaproductmadefromhigh-strengthsteel.Maximum
bility of regulatory limitations prior to use.
stresslimitscanbespecifiedtominimizethis.Otherproperties
2. Terminology
affected by stress include corrosion resistance, dimensional
stability, cracking, and peeling.
2.1 Definitions:
2.1.1 compressive stress (−)—stress that tends to cause a
4.3 In control of electroforming solutions, the effects of
deposit to expand.
stress are more widely recognized, and the control of stress is
2.1.2 internal stress—thenetstressthatremainsinadeposit usuallynecessarytoobtainausableelectroform.Internalstress
whenitisfreefromexternalforces.Theinternalstresstendsto limits can be determined and specified for production control.
compress or stretch the deposits.
4.4 Internal stress values obtained by the spiral contracto-
2.1.3 tensile stress (+)—stress that tends to cause a deposit
meterdonotnecessarilyreflecttheinternalstressvaluesfound
to contract.
onapartplatedinthesamesolution.Internalstressvarieswith
many factors, such as coating thickness, preparation of
3. Summary of Test Method
substrate, current density, and temperature, as well as the
3.1 The test method of measuring stress with the spiral
solution composition. Closer correlation is achieved when the
contractometer is based on plating on the outside of a helix. test conditions match those used to coat the part.
The helix is formed by winding a strip around a cylinder,
5. Apparatus
followed by annealing. In operation, one end of the helix is
fixedandtheotherisallowedtomoveasstressesdevelop.The
5.1 The spiral contractometer is described by A. Brenner
2
free end is attached to an indicating needle through gears that
and S. Senderoff.
NOTE 1—Spiral contractometers are available from many of the
1
ThistestmethodisunderthejurisdictionofASTMCommitteeB08onMetallic
suppliers of nickel sulfamate.
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on
Test Methods.
Current edition approved Nov. 1, 2010. Published November 2010. Originally
e01 2
approved in 1978. Last previous edition approved in 2006 as B636–84(2006) . Brenner, A., and Senderoff, S., Proceedings of the American Electroplaters
DOI: 10.1520/B0636-84R10. Society, Vol 35, 1948, p. 53.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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B636 − 84 (2010)
5.2 Helices shall be stopped-off on the inside to prevent shall be analyzed to determine if any changes in solution
plating.Helicesareavailablewithorwithoutapermanentinert composition have occurred during the test.
coating on the insides (see Appendix X1). 6.4.1 Testsrunonelectroplatingsolutionsusinginsoluble
...
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