ASTM D6675-23

Standard Practice for Salt-Accelerated Outdoor Cosmetic Corrosion Testing of Organic Coatings on Automotive Sheet Steel

SIGNIFICANCE AND USE
3.1 Tests of the type described in this practice are used to evaluate the corrosion resistance of organic coatings on metal products exposed to highly salty environments, such as areas subjected to deicing salts or coastal areas. Exposure conditions are complex and changeable. Important factors include climate, time of year, presence of pollution, and so forth. Generally it is difficult, if not impossible, to define or measure precisely all the factors that influence degradation. Repeated exposure testing during different seasons and over a period of at least two years is required to obtain results representative of any given location.
SCOPE
1.1 This practice is designed to assist procedures to be followed when conducting outdoor exposures to evaluate cosmetic corrosion that might occur in steel panels covered with an organic coating that has been damaged. The outdoor exposures described are based on Practices G7 and G50 and include periodic wetting of the test specimens with a salt solution.  
1.2 The methods of preparing test specimens and the particular exposure requirements of materials are beyond the scope of this practice.  
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 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-Jan-2023
• ICS: 43.040.60 - Bodies and body components
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.27 - Accelerated Testing

Relations

• Refers: ASTM D1730-09(2020) - Standard Practices for Preparation of Aluminum and Aluminum-Alloy Surfaces for Painting
• Effective Date: 01-May-2020
• Refers: ASTM D610-08(2019) - Standard Practice for Evaluating Degree of Rusting on Painted Steel Surfaces
• Effective Date: 01-Jan-2019
• Refers: ASTM D1014-18 - Standard Practice for Conducting Exterior Exposure Tests of Paints and Coatings on Metal Substrates
• Effective Date: 01-Apr-2018
• Refers: ASTM D823-17 - Standard Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on Test Panels
• Effective Date: 01-Dec-2017
• Refers: ASTM D1654-08(2016) - Standard Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive Environments
• Effective Date: 01-Dec-2016
• Refers: ASTM D1730-09(2014) - Standard Practices for Preparation of Aluminum and Aluminum-Alloy Surfaces for Painting
• Effective Date: 01-Nov-2014
• Refers: ASTM D610-08(2012) - Standard Practice for Evaluating Degree of Rusting on Painted Steel Surfaces
• Effective Date: 01-Nov-2012
• Refers: ASTM D823-95(2012) - Standard Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on Test Panels
• Effective Date: 01-Nov-2012
• Refers: ASTM D3170-12 - Standard Test Method for Chipping Resistance of Coatings
• Effective Date: 15-Jul-2012
• Refers: ASTM D609-00(2012) - Standard Practice for Preparation of Cold-Rolled Steel Panels for Testing Paint, Varnish, Conversion Coatings, and Related Coating Products
• Effective Date: 01-Jun-2012
• Refers: ASTM B117-11 - Standard Practice for Operating Salt Spray (Fog) Apparatus
• Effective Date: 01-Oct-2011
• Refers: ASTM D2201-99(2011) - Standard Practice for Preparation of Zinc-Coated and Zinc-Alloy-Coated Steel Panels for Testing Paint and Related Coating Products
• Effective Date: 01-Jul-2011
• Refers: ASTM G50-10 - Standard Practice for Conducting Atmospheric Corrosion Tests on Metals
• Effective Date: 01-Sep-2010
• Refers: ASTM B117-09 - Standard Practice for Operating Salt Spray (Fog) Apparatus
• Effective Date: 01-Jul-2009
• Refers: ASTM D1730-09 - Standard Practices for Preparation of Aluminum and Aluminum-Alloy Surfaces for Painting
• Effective Date: 15-Apr-2009

Overview

ASTM D6675-23, "Standard Practice for Salt-Accelerated Outdoor Cosmetic Corrosion Testing of Organic Coatings on Automotive Sheet Steel," provides a standardized methodology for evaluating the cosmetic corrosion resistance of organic coatings exposed to highly salty outdoor environments. This standard is crucial within the automotive, coatings, and materials industries, where assessing the durability and protective properties of coatings against corrosion is essential, especially in challenging environments influenced by deicing salts or coastal exposure.

ASTM D6675-23 details procedures for outdoor exposure testing, including the periodic wetting of damaged coated steel panels with a salt solution and specifies reporting requirements to ensure consistent and comparable results.

Key Topics

• Cosmetic Corrosion Testing: Focuses on "outside-in" corrosion, which begins on visible painted surfaces, typically at nicks, scratches, or other damage to the coating.
• Test Conditions: Evaluates corrosion performance in complex, variable outdoor environments where factors like climate, season, and pollution can affect results.
• Salt-Accelerated Exposure: Uses periodic application of a salt solution, typically a 5% aqueous sodium chloride, to simulate harsh conditions similar to those found in areas routinely exposed to road deicing salts or marine influences.
• Comparative Testing: Emphasizes the necessity of control specimens for meaningful comparison, due to variability in environmental factors.
• Reporting and Evaluation: Specifies comprehensive reporting guidelines, including specimen preparation, exposure conditions, and corrosion assessment methodologies.
• Safety and Compliance: Requires users to establish safety, health, and environmental protocols and comply with applicable regulations.

Applications

ASTM D6675-23 is widely applied in:

• Automotive Manufacturing and Supply Chain: Assesses the cosmetic corrosion resistance of coated steel used in external automotive body panels, helping manufacturers qualify materials and coatings for durability in real-world conditions.
• Coating Development and Quality Control: Supports formulators and quality personnel in testing new organic coatings or verifying the performance of existing products under conditions replicating high salt exposure.
• Material Research and Development: Facilitates the evaluation of innovations in coating technology, such as advanced paint systems or pre-treatment processes.
• Comparative Performance Analysis: Allows organizations to benchmark new products or processes against established standards or competitive offerings.

By providing a repeatable outdoor accelerated corrosion protocol, ASTM D6675-23 ensures that test results are representative of actual service and can be used to make informed decisions about material selection, product warranties, and corrosion prevention strategies.

Related Standards

ASTM D6675-23 references several other critical standards for corrosion and coating performance testing, including:

• ASTM B117 - Practice for Operating Salt Spray (Fog) Apparatus
• ASTM D609 - Practice for Preparation of Cold-Rolled Steel Panels for Testing Paint
• ASTM D610 - Practice for Evaluating Degree of Rusting on Painted Steel
• ASTM D1014 - Practice for Conducting Exterior Exposure Tests on Paints and Coatings on Metals
• ASTM D1654 - Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive Environments
• ASTM G7 and ASTM G50 - Practices related to natural and atmospheric corrosion testing

For rigorous and reliable outdoor corrosion assessment of coated automotive sheet steel, ASTM D6675-23 provides the essential framework that supports quality improvement, product development, and regulatory compliance across the automotive and anti-corrosion coatings industries.

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: D6675 − 23
Standard Practice for
Salt-Accelerated Outdoor Cosmetic Corrosion Testing of
Organic Coatings on Automotive Sheet Steel
This standard is issued under the fixed designation D6675; 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.
INTRODUCTION
Corrosion of painted sheet steel of auto bodies is classified according to the initial location and
direction of the corrosive attack. When the corrosion starts on the visible exterior surface, mostly at
nicks and scratches in the paint, it is called “cosmetic” or “outside in” corrosion. Corrosion initiated
at an interior surface or within a closed or semi-closed part is called “perforation” or “inside out”
corrosion.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This practice is designed to assist procedures to be
B117 Practice for Operating Salt Spray (Fog) Apparatus
followed when conducting outdoor exposures to evaluate
D609 Practice for Preparation of Cold-Rolled Steel Panels
cosmetic corrosion that might occur in steel panels covered
for Testing Paint, Varnish, Conversion Coatings, and
with an organic coating that has been damaged. The outdoor
Related Coating Products
exposures described are based on Practices G7 and G50 and
D610 Practice for Evaluating Degree of Rusting on Painted
include periodic wetting of the test specimens with a salt
Steel Surfaces
solution.
D823 Practices for Producing Films of Uniform Thickness
1.2 The methods of preparing test specimens and the par-
of Paint, Coatings and Related Products on Test Panels
ticular exposure requirements of materials are beyond the
D1014 Practice for Conducting Exterior Exposure Tests of
scope of this practice. Paints and Coatings on Metal Substrates
D1654 Test Method for Evaluation of Painted or Coated
1.3 The values stated in SI units are to be regarded as the
Specimens Subjected to Corrosive Environments
standard. The values given in parentheses are for information
D1730 Practices for Preparation of Aluminum and
only.
Aluminum-Alloy Surfaces for Painting
1.4 This standard does not purport to address all of the D2201 Practice for Preparation of Zinc-Coated and Zinc-
safety concerns, if any, associated with its use. It is the Alloy-Coated Steel Panels for Testing Paint and Related
responsibility of the user of this standard to establish appro- Coating Products
D3170 Test Method for Chipping Resistance of Coatings
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use. G7 Practice for Natural Weathering of Materials
G50 Practice for Conducting Atmospheric Corrosion Tests
1.5 This international standard was developed in accor-
on Metals
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
3. Significance and Use
Development of International Standards, Guides and Recom-
3.1 Tests of the type described in this practice are used to
mendations issued by the World Trade Organization Technical
evaluate the corrosion resistance of organic coatings on metal
Barriers to Trade (TBT) Committee.
products exposed to highly salty environments, such as areas
subjected to deicing salts or coastal areas. Exposure conditions
This practice is under the jurisdiction of ASTM Committee D01 on Paint and
Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.27 on Accelerated Testing. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Feb. 1, 2023. Published February 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2001. Last previous edition approved in 2015 as D6675 – 01 (2015). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D6675-23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6675 − 23
3,4,5,6
test, or any other natural exposure conducted in severe locations.
are complex and changeable. Important factors include climate,
time of year, presence of pollution, and so forth. Generally it is
7.3 The application of electrolyte solution should be per-
difficult, if not impossible, to define or measure precisely all
formed on the scheduled day regardless of the weather condi-
the factors that influence degradation. Repeated exposure
tions such as rain or snow. Unless otherwise agreed upon, spray
testing during different seasons and over a period of at least
the panels after the evaporation of the morning dew formation.
two years is required to obtain results representative of any
Do not remove snow and ice from the specimens prior to the
given location.
electrolyte solution application.
8. Periods of Exposure
4. Test Site
8.1 The duration of exposure should be specified on one of
4.1 Climate and Location—Historically, the preferred loca-
the following bases:
tion for the racks is a cleared, grass covered area in a region
8.1.1 Exposure for a specified number of days, months or
that potentially promotes corrosion, such as a subtropical or
years. The report shall indicate exact dates of exposure.
northern temperate climate. Arid (desert) climates have typi-
8.1.2 Exposure until a specified level of corrosion or deg-
cal
...

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: D6675 − 01 (Reapproved 2015) D6675 − 23
Standard Practice for
Salt-Accelerated Outdoor Cosmetic Corrosion Testing of
Organic Coatings on Automotive Sheet Steel
This standard is issued under the fixed designation D6675; 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.
INTRODUCTION
Corrosion of painted sheet steel of auto bodies is classified according to the initial location and
direction of the corrosive attack. When the corrosion starts on the visible exterior surface, mostly at
nicks and scratches in the paint, it is called “cosmetic” or “outside in” corrosion. Corrosion initiated
at an interior surface or within a closed or semi-closed part is called “perforation” or “inside out”
corrosion.
1. Scope
1.1 This practice is designed to assist procedures to be followed when conducting outdoor exposures to evaluate cosmetic
corrosion that might occur in steel panels covered with an organic coating that has been damaged. The outdoor exposures described
are based on PracticePractices G7 and G50 and include periodic wetting of the test specimens with a salt solution.
1.2 The methods of preparing test specimens and the particular exposure requirements of materials are beyond the scope of this
practice.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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 healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use.
1.5 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
2.1 ASTM Standards:
B117 Practice for Operating Salt Spray (Fog) Apparatus
D609 Practice for Preparation of Cold-Rolled Steel Panels for Testing Paint, Varnish, Conversion Coatings, and Related Coating
Products
This practice is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.27 on Accelerated Testing.
Current edition approved Dec. 1, 2015Feb. 1, 2023. Published December 2015February 2023. Originally approved in 2001. Last previous edition approved in 20112015
as D6675 – 01 (2011).(2015). DOI: 10.1520/D6675-01R15.10.1520/D6675-23.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6675 − 23
D610 Practice for Evaluating Degree of Rusting on Painted Steel Surfaces
D823 Practices for Producing Films of Uniform Thickness of Paint, Coatings and Related Products on Test Panels
D1014 Practice for Conducting Exterior Exposure Tests of Paints and Coatings on Metal Substrates
D1654 Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive Environments
D1730 Practices for Preparation of Aluminum and Aluminum-Alloy Surfaces for Painting
D2201 Practice for Preparation of Zinc-Coated and Zinc-Alloy-Coated Steel Panels for Testing Paint and Related Coating
Products
D3170 Test Method for Chipping Resistance of Coatings
G7 Practice for Natural Weathering of Materials
G50 Practice for Conducting Atmospheric Corrosion Tests on Metals
G117 Guide for Calculating and Reporting Measures of Precision Using Data from Interlaboratory Wear or Erosion Tests
(Withdrawn 2016)
3. Significance and Use
3.1 Tests of the type described in this practice may be are used to evaluate the corrosion resistance of organic coatings on metal
products exposed to highly salty environments, such as areas subjected to deicing salts or coastal areas. Exposure conditions are
complex and changeable. Important factors include climate, time of year, presence of pollution, and so forth. Generally it is
difficult, if not impossible, to define or measure precisely all the factors that influence degradation. Repeated exposure testing
during different seasons and over a period of at least two years is required to obtain results representative of any given location.
3.2 Control specimens must always be used because this is a comparative test.
4. Test Site
4.1 Climate and Location—The Historically, the preferred location for the racks is a cleared, grass covered area. area in a region
that potentially promotes corrosion, such as a subtropical or northern temperate climate. Arid (desert) climates have typically been
avoided. Other conditions can be agreed upon between the parties involved.
4.2 Rack Position and Type—45° open rack facing the equator, direct weathering unless other conditions are agreed upon between
the buyer and seller.
NOTE 1—Information on location, rack construction, and position are given in Practices D1014, G7, and G50.
5. Test Specimens
5.1 Methods for the preparation of test panels and substrates are given in Practices D609, D1730 and D2201. Practice D823 covers
techniques for producing uniformly coated test panels.
5.2 Control s
...