ASTM B636/B636M-15(2021)

• Abstract:

  SIGNIFICANCE AND USE; 5.1 The spiral contractometer, properly used, will give reproducible results (see 9.5) 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. ; 5.2 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. ; 5.3 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. ; 5.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. ; 1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

• Status: Published
• Publication Date: 30-Sep-2021
• ICS: 25.220.40 - Metallic coatings
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.10 - Test Methods

• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM E177-10 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2010
• Refers: ASTM E691-08 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Oct-2008
• Refers: ASTM E177-08 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2008
• Refers: ASTM E177-06b - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 15-Nov-2006
• Refers: ASTM E177-06a - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2006
• Refers: ASTM E691-05 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2005
• Refers: ASTM E177-04e1 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2004
• Refers: ASTM E177-04 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2004
• Refers: ASTM E177-06 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2004
• Refers: ASTM E177-90a(2002) - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 10-Jan-2002
• Refers: ASTM E691-99 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 10-May-1999

Overview

ASTM B636/B636M-15(2021) is the international standard test method developed by ASTM International for the measurement of internal stress in plated metallic coatings using the spiral contractometer. This standard provides an objective procedure for quantifying internal stresses in metals deposited from plating solutions on a helical cathode. Accurate determination of internal stress is vital because it directly affects the performance, durability, and quality of plated or electroformed components. Both electrolytic and autocatalytic metal deposits can be assessed with this method.

The document was formulated according to globally recognized standards principles and is widely applied in quality assurance and process control in the electroplating industry.

Key Topics

• Internal Stress Definition: The method measures the net stress retained in a metallic coating after external forces are removed, distinguishing between tensile and compressive stresses.
• Spiral Contractometer Usage: This instrument evaluates how the metallic deposit, when plated onto a prepared helix, causes either tightening or loosening due to internal stress, with measurements either mechanically or electronically magnified.
• Factors Affecting Accuracy:
  • Coating Thickness
  • Current Density in Electroplating
  • Solution Temperature
  • Solution Composition
  • Surface Preparation and Substrate Condition
• Calibration and Repeatability: Emphasizes precise calibration and environmental controls for reproducible results. Results are deemed repeatable if three consecutive tests are within ±10% of the mean value.
• Reporting Parameters: Requires details on plated metal, solution composition, measurement apparatus, deposit thickness, current density, temperature, and pH for comprehensive reporting.

Applications

ASTM B636/B636M-15(2021) is essential in the following applications:

• Process Control in Electroplating: Ensures that internal stresses remain within specified limits, preventing potential product failures such as cracking, peeling, or loss of dimensional stability.
• Electroforming Production: Allows manufacturers to control and fine-tune electroforming solutions to achieve usable, defect-free electroforms.
• Quality Assurance: Both producers and purchasers use this test method to set and verify stress thresholds for compliance with performance and reliability requirements.
• Material Selection and Development: R&D teams evaluate new plating solutions or substrates by analyzing their impact on internal stress and related mechanical and chemical properties.
• Troubleshooting: Identifies problematic process variables when product performance is compromised due to excessive internal plating stress.

Related Standards

For comprehensive coverage of internal stress measurement and electroplating quality, the following standards are often referenced in conjunction with ASTM B636/B636M-15(2021):

• ASTM E177: Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• ASTM E691: Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

Other relevant ASTM standards address metallic and inorganic coatings, coating thickness measurement, and the physical testing of metallic deposits.

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Keywords: ASTM B636, internal stress, plated metallic coatings, spiral contractometer, electroplating, autocatalytic deposits, stress measurement, quality assurance, process control, testing standards.

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B636/B636M − 15 (Reapproved 2021)
Standard Test Method for
Measurement of Internal Stress of Plated Metallic Coatings
with the Spiral Contractometer
This standard is issued under the fixed designation B636/B636M; 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 3.1.2 internalstress—thenetstressthatremainsinadeposit
whenitisfreefromexternalforces.Theinternalstresstendsto
1.1 This test method covers the use of the spiral contracto-
compress or stretch the deposits.
meter for measuring the internal stress of metallic coatings as
3.1.3 tensile stress (+)—stress that tends to cause a deposit
produced from plating solutions on a helical cathode. The test
to contract.
method can be used with electrolytic and autocatalytic depos-
its.
4. Summary of Test Method
1.2 The values stated in either SI units or inch-pound units
4.1 The test method of measuring stress with the spiral
are to be regarded separately as standard. The values stated in
contractometer is based on plating on the outside of a helix.
each system may not be exact equivalents; therefore, each
The helix is formed by winding a strip around a cylinder,
system shall be used independently of the other. Combining
followed by annealing. In operation, one end of the helix is
values from the two systems may result in non-conformance
fixedandtheotherisallowedtomoveasstressesdevelop.The
with the standard.
free end is attached to an indicating needle through gears that
1.3 This standard does not purport to address all of the
magnify the movement of the helix.As the helix is plated, the
safety concerns, if any, associated with its use. It is the
stress in the deposit causes the helix to wind more tightly or to
responsibility of the user of this standard to establish appro-
unwind, depending on whether the stress is compressive (−) or
priate safety, health, and environmental practices and deter-
tensile (+). From the amount of needle deflection and other
mine the applicability of regulatory limitations prior to use.
data, the internal stress is calculated.
1.4 This international standard was developed in accor-
4.2 With instrument modifications, the movement of the
dance with internationally recognized principles on standard-
helixcanbemeasuredelectronicallyinsteadofmechanicallyas
ization established in the Decision on Principles for the
described in 4.1.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
5. Significance and Use
Barriers to Trade (TBT) Committee.
5.1 The spiral contractometer, properly used, will give
2. Referenced Documents
reproducible results (see 9.5) over a wide range of stress
values. Internal stress limits with this method can be specified
2.1 ASTM Standards:
for use by both the purchaser and the producer of plated or
E177Practice for Use of the Terms Precision and Bias in
electroformed parts.
ASTM Test Methods
E691Practice for Conducting an Interlaboratory Study to
5.2 Platingwithlargetensilestresseswillreducethefatigue
Determine the Precision of a Test Method
strengthofaproductmadefromhigh-strengthsteel.Maximum
stresslimitscanbespecifiedtominimizethis.Otherproperties
3. Terminology
affected by stress include corrosion resistance, dimensional
stability, cracking, and peeling.
3.1 Definitions:
3.1.1 compressive stress (−)—stress that tends to cause a
5.3 In control of electroforming solutions, the effects of
deposit to expand.
stress are more widely recognized, and the control of stress is
usuallynecessarytoobtainausableelectroform.Internalstress
limits can be determined and specified for production control.
ThistestmethodisunderthejurisdictionofASTMCommitteeB08onMetallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on
5.4 Internal stress values obtained by the spiral contracto-
Test Methods.
meterdonotnecessarilyreflecttheinternalstressvaluesfound
Current edition approved Oct. 1, 2021. Published October 2021. Originally
onapartplatedinthesamesolution.Internalstressvarieswith
approved in 1978. Last previous edition approved in 2015 as B636–15. DOI:
10.1520/B0636_B0636M-15R21. many factors, such as coating thickness, preparation of
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B636/B636M − 15 (2021)
substrate, current density, and temperature, as well as the density range under consideration. It is important that the
solution composition. Closer correlation is achieved when the current be measured and controlled closely throughout the
test conditions match those used to coat the part.
stress test.Variations in currents shall be held to less than 2%.
7.3 Because the temperature of the plating solution may
6. Apparatus
affect the internal stress, it shall be maintained within 2°C
6.1 The spiral contractometer is described by A. Brenner
2 [6.5°F]duringthetest.Theinitialrestpointoftheindicatorand
and S. Senderoff.
the final rest point are both taken at the operating temperature
NOTE 1—Spiral contractometers are available from many of the
of the plating solution to eliminate thermal stresses.
suppliers of nickel sulfamate.
7.4 The solution composition shall not vary during the test.
6.2 Helices shall be stopped-off on the inside to prevent
Usually,iftherepeatabilitytestsin9.5aremet,thesolutioncan
plating.Helicesareavailablewithorwithoutapermanentinert
be assumed to be unchanged during the test runs. Conversely,
coating on the insides (see Appendix X1).
when the repeatability tests are not met, the plating solution
6.3 Theclampsholdingthehelixtothecontractometershall
shall be analyzed to determine if any changes in solution
be coated with an inert nonconductive coating to prevent their
composition have occurred during the test.
plating and acting as thieves.
7.4.1 Testsrunonelectroplatingsolutionsusinginsolubleor
6.4 For testing electroplating solutions, anodes are placed
inefficient anodes could result in significant solution changes
equidistant from the helix and symmetrically positioned to
during the test.
produce even plate distribution. A minimum of four anodes is
7.4.2 When testing autocatalytic plating solutions, the con-
required. A concentric anode arrangement is preferred.
stituents of the plating solution may be significantly depleted
6.5 Laboratory tests on electroplating solutions shall utilize
during the test, unless replenished.
at least 3.7 L of solution.A4-L beaker with an annular anode
arrangement is convenient. Use of this volume or larger will
7.5 Arelationship between the surface area to be plated and
minimize solution changes due to electrolysis during the test.
the volume of autocatalytic plating solutions exists that may
affect the character of the deposit. In testing autocatalytic
6.6 Laboratory tests on autocatalytic plating solutions are
plating solutions, the ratio of plated surface area to the volume
doneina1-L,tall-formbeaker.Obviously,noanodesareused.
of solution that is normally used in the plating tank shall be
7. Factors Affecting Accuracy
maintained. When using proprietary solutions, the supplier’s
recommendation shall be followed.
7.1 Variations in the preparation of the helix may cause
substantial variations in results.
8. Calibration
7.1.1 Stop-off material shall be applied properly to the
interior of the helix. The stop-off material shall be thin and
8.1 Calibrate the instrument as directed in the manufactur-
flexible to permit the helix to move freely during the test. A
er’s instructions.
coating weight of less than 3 mg/in. is satisfactory.
8.2 The frequency of calibration will vary with use and
NOTE 2—The inside shall be stopped-off with some inert, flexible
extent of attack on the helices from the chemical stripping.
coating. One acceptable stop-off material is “Microstop.” One part of
“Microstop” is diluted with two parts of acetone before use. Any nickel When visible attack is noted, discard the helix.
deposited on the inside of the helix will exhibit an opposing effect.
8.3 The calibration procedure consists essentially of deter-
7.1.2 Helices that have been permanently coated on the
mining the force required per degree of dial deflection. A
inside with TFE-fluorocarbon may give variable results when
known mass is suspended over a small pulley on a lever arm
testing near-zero stresses.
with the helix mounted in place. The degree of deflection is
7.1.3 Cleaning variations and surface preparation of the
read from the dial. The data required for the calibration
helix before the test can produce varying results. For example,
calculations as expressed in metric units are as follows:
electrocleaning of the helix shall always be cathodic and
controlled with respect to current, time, and temperature.
w = mass used in calibrating, kg,
Anodic cleaning at this stage can give wide variations. Abra-
a = length of lever arm, m,
sive cleaning of the helix and the use of etchants shall be
p = pitch of helix, m,
avoided.
t = thickness of the strip used to make the helix, m,
7.1.4 Very thin deposits of less than about 3 µm [1.18 ×
deg = degreedeflection;differenceindialreadingscaused
def
–4
10 in.] are influenced more by the surface conditions and
by mass,
preparation of the helix than are thicker deposits.
g = 9.8 m/s (acceleration of free fall), and
Z = calibration constant of the helix
7.2 Internal stress varies with current density used in elec-
troplating. The variation is not predictable and depends on the MPa
S D
metal being deposited, impurities or additives, and the current m deg
def
where
2 2 w a g
~ !~ !~ !
Brenner, A., and Senderoff, S., Proceedings of the American Electroplaters
Z 5 310
Society, Vol 35, 1948, p. 53. p t deg
~ !
def
B636/B636M − 15 (2021)
9. Procedure Then τ=W/(d)A
9.1 The procedure will vary with the solution being tested. Z 3D
Internalstress, S, inMPa 5 (1)
Follow the instructions given by the supplier carefully. Varia- τ
NOTE 3—This value is an average stress and is uncorrected for the
tions in the procedure can produce variations in results. Give
effects of the differences in Young’s modulus between the helix and the
appropriate attention to the factors in Section 7. A detailed
deposit.Italsoassumesarelativelythindepositonthehelix.Ifacorrected
procedurefornickelplatingsolutionsappearsinAppendixX1.
or truer stress, S , is desired:
T
9.2 Position the spiral contractometer in electroplating so-
E 3t
S 5 S 11 (2)
F G
S D
lutions so that it is equidistant from the anodes. Position the T
E 3τ
anodesonatleastfoursideswhentheyareusedinaproduction
where:
tank or use a concentric anode arrangement. Do not place the
E = Young’s modulus of the deposit, and
spiral contractometer between the tank anodes and the work
E = Young’s modulus of the helix.
being plated in a production tank. A separate ammeter and
currentcontrolarerequired.Ifthetestisrunonasampleofthe
Normally, the correction made above is less than the
solution, use a 4-L beaker.
experimental errors in the procedure and is infrequently used.
9.3 When testing autocatalytic plating solutions, maintain
11. Report
the proper surface area-to-solution volume ratio (see 7.5).
11.1 Whenreportinginternalstressvalues,itisnecessaryto
9.4 The conditions of the test are usually chose
...