ASTM B975-22

Standard Test Method for Measurement of Internal Stress of Metallic Coatings by Split Strip Evaluation (Deposit Stress Analyzer Method)

SIGNIFICANCE AND USE
5.1 Internal stress in applied coatings exhibits potential to cause a breakdown of resistance to corrosion and erosion as a result of the formation of fractures from micro-cracking and macro-cracking within the applied coating. This phenomenon can also cause blistering, peeling, reduction of fatigue strength, and loss. The resulting stress can be tensile in nature, causing the deposit to contract, or compressive in nature, causing the deposit to expand.  
5.2 To maintain quality assurance by the bent strip method, it is necessary to monitor production processes for acceptable levels of internal deposit stress in applied coatings. Most low values are false. Initial values tend to be lower than the actual value because of the effect of stock material edge burrs and the resistance of the stock material to bending. Excessive deposit thickness causes lower-than-true value since the coating overpowers and changes the initial modulus of elasticity of the test piece, which becomes more difficult to bend as the coating continues to build upon it. This phenomenon can be corrected considerably by use of a formula that compensates for modulus of elasticity differences between the deposit and the substrate materials, but it does remain a factor. See Eq 3.
Note 1: The highest value of the internal deposit stress as obtained on a stress-versus-plating-thickness curve is usually the truest value of the internal deposit stress.
SCOPE
1.1 This test method for determining the internal tensile or compressive stress in applied coatings is quantitative. It is applicable to metallic layers that are applied by the processes of electroplating or chemical deposition that exhibit internal tensile or compressive stress values from 200 psi to 145 000 psi (1.38 MPa to 1000 MPa).  
1.2 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other. Conversion between unit systems may result in errors that can cause confusion and should be avoided.  
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.

General Information

• Status: Published
• Publication Date: 31-Oct-2022
• ICS: 25.220.40 - Metallic coatings
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.10 - Test Methods

Standards Content (Sample)

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: B975 − 22
Standard Test Method for
Measurement of Internal Stress of Metallic Coatings by Split
1
Strip Evaluation (Deposit Stress Analyzer Method)
This standard is issued under the fixed designation B975; 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.
INTRODUCTION
The split strip method provides a determination of the internal tensile and compressive stress in
metallic and nonmetallic coatings. Internal stress is expressed in pounds per square inch or
megapascals.
1. Scope* 2. Referenced Documents
2
2.1 ASTM Standards:
1.1 This test method for determining the internal tensile or
B636Test Method for Measurement of Internal Stress of
compressive stress in applied coatings is quantitative. It is
Plated Metallic Coatings with the Spiral Contractometer
applicable to metallic layers that are applied by the processes
E177Practice for Use of the Terms Precision and Bias in
of electroplating or chemical deposition that exhibit internal
ASTM Test Methods
tensile or compressive stress values from 200psi to 145 000
E691Practice for Conducting an Interlaboratory Study to
psi (1.38MPa to 1000 MPa).
Determine the Precision of a Test Method
1.2 Units—The values stated in either SI units or inch-
3. Terminology
pound units are to be regarded separately as standard. The
values stated in each system are not necessarily exact equiva- 3.1 Definitions of Terms Specific to This Standard:
lents; therefore, to ensure conformance with the standard, each 3.1.1 average deposit thickness, n—the deposit weight in
grams divided by the specific gravity of the deposit in grams
system shall be used independently of the other. Conversion
per cubic centimetre multiplied by the plated deposit surface
between unit systems may result in errors that can cause
area per test strip (see Eq 2).
confusion and should be avoided.
3.1.2 constant K, n—this certifiable calibrated number is
1.3 This standard does not purport to address all of the
determined experimentally for each material lot of test strips
safety concerns, if any, associated with its use. It is the
manufacturedtoenablesimplemathematicalcalculationofthe
responsibility of the user of this standard to establish appro-
internal deposit stress while factoring the influence of the
priate safety, health, and environmental practices and deter-
percent elongation difference between the deposit and the
mine the applicability of regulatory limitations prior to use.
substrate without the use of complicated bent strip formulas.
1.4 This international standard was developed in accor-
See Section 10.
dance with internationally recognized principles on standard-
3.1.3 internal stress, n—stress in a given layer of coating
ization established in the Decision on Principles for the
can result from foreign atoms or materials in the layer that
Development of International Standards, Guides and Recom-
stressthenaturalstructureofthedepositasthecoatingisbeing
mendations issued by the World Trade Organization Technical
formed from sources independent of foreign atoms such as
Barriers to Trade (TBT) Committee.
misfit dislocations and the result of additional processing.
3.1.3.1 compressive stress (-), n—stressthattendstocausea
deposit to expand.
1
ThistestmethodisunderthejurisdictionofASTMCommitteeB08onMetallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on
2
Test Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2022. Published December 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
ɛ1
approved in 2015. Last previous edition approved in 2018 as B975–18 . DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/B0975-22. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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B975 − 22
3.1.3.2 tensile stress (+), n—stress that tends to cause a
deposit to contract.
3.1.3.3 Discussion—Stress that develops in a given layer of
materialismeasuredaspoundspersquareinchormegapascals
where 1 MPa = 145 psi.
3.1.4 modulus of elasticity, n—stress required to produce
unit strain, which may be a change in length (Young’s
modulus), a twist of shear (modulus of rigidity or modulus of
to
...

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.
´1
Designation: B975 − 18 B975 − 22
Standard Test Method for
Measurement of Internal Stress of Metallic Coatings by Split
1
Strip Evaluation (Deposit Stress Analyzer Method)
This standard is issued under the fixed designation B975; 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
ε NOTE—Footnote 5 was editorially corrected in February 2020.
INTRODUCTION
The deposit stress analyzer split strip method provides a rapid, accurate, and economical means for
the determination of the internal tensile and compressive stress in metallic and nonmetallic coatings.
Internal stress is expressed in pounds per square inch or megapascals. This procedure for measuring
internal stress offers the advantages of test specimens that are pre-calibrated by the manufacturer, a
small test specimen coating surface area, and rapid determination of the internal stress in the applied
coating.
1. Scope Scope*
1.1 This test method for determining the internal tensile or compressive stress in applied coatings is quantitative. It is applicable
to metallic layers that are applied by the processes of electroplating or chemical deposition that exhibit internal tensile or
compressive stress values from 200200 psi to 145 000 psi (1.38(1.38 MPa to 1000 MPa).
1.2 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in
each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used
independently of the other, and values from the two systems shall not be combined.other. Conversion between unit systems may
result in errors that can cause confusion and should be avoided.
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.
2. Referenced Documents
2
2.1 ASTM Standards:
B636 Test Method for Measurement of Internal Stress of Plated Metallic Coatings with the Spiral Contractometer
1
This test method is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on Test
Methods.
Current edition approved Dec. 1, 2018Nov. 1, 2022. Published January 2019December 2022. Originally approved in 2015. Last previous edition approved in 20152018
ɛ1
as B975 – 15.B975 – 18 . DOI: 10.1520/B0975-18E01.10.1520/B0975-22.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
B975 − 22
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3
2.2 IEC Standard:
IEC 61010 Safety Requirements for Electrical Equipment for Measurement, Control, and Laboratory Use
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 average deposit thickness, n—average deposit thickness equals the deposit weight in grams divided by the specific gravity
of the deposit in grams per cubic centimetre multiplied by the plated deposit surface area per test strip (see Eq 32).
3.1.2 constant K, n—this certifiable calibrated number is determined experimentally for each material lot of test strips
manufactured to enable simple mathematical calculation of the internal deposit stress while factoring the influence of the percent
elongation difference between the deposit and the substrate without the use
...