ASTM D6492-99(2022)

Standard Practice for Detection of Hexavalent Chromium On Zinc and Zinc/Aluminum Alloy Coated Steel

ABSTRACT
This practice can be used for detection of hexavalent chromium on galvanized and zinc/aluminum alloy coated steel surfaces. Hexavalent chromium-bearing treatments (passivates) can be applied to coated steels to prevent storage stain. Chrome passivation may interfere with the successful pretreatment of galvanized steel, as well as contaminate cleaning and pretreatment baths on a coil coating line. This practice is designed to be a qualitative means of screening chrome passivated coils from those which are not chrome passivated. The following materials will be required to perform the stripping procedure: (1) dark colored or brown polyethylene wash bottle, or brown glass dropper bottle, and (2) test specimens which may be cut panels or coil stock. The following chemical reagents are required to perform this procedure: 1,5-diphenylcarbohydrazide, acetone, ethanol, phosphoric acid, and distilled water. The preparation of indicator solution, procedure of detection, and evaluation of pink color development are detailed. If a material that yields a negative result is suspected of having chromium on the surface, instrumental methods should be used. This technique is not recommended for acrylic resin containing passivation treatments.
SCOPE
1.1 This practice can be used to detect the presence of hexavalent chromium on galvanized and zinc/aluminum alloy coated steel surfaces. Hexavalent chromium-bearing treatments (passivates) can be applied to coated steels to prevent storage stain. While passivated 55 % aluminum-zinc alloy coated steel is commonly painted, passivated galvanized steel is not. Chrome passivation may interfere with the successful pretreatment of galvanized steel, as well as contaminate cleaning and pretreatment baths on a coil coating line.  
1.2 The amount of hexavalent chromium that will cause the indicator to produce a discernible pink color is in the range of 0.5 parts per million dissolved in the indicator solution. It is possible that a coated steel surface that produces a negative result does have chromium on the surface. If a material that yields a negative result is suspected of having chromium on the surface, instrumental methods should be used. Chrome deposits of 1 mg/ft2 can be easily missed by analytical instruments such as the scanning electron microscope with energy dispersive x-ray analysis (EDXA) capability. Auger electron spectroscopy (AES) or electron spectroscopy for chemical analysis (ESCA) can identify chemical species present in the levels required for adequate detection. Stripping the metallic coating and analyzing for chrome by atomic absorption or inductively coupled plasma can also give reliable results in detecting the presence of chrome.  
1.3 This practice is designed to be a qualitative means of screening chrome passivated coils from those which are not chrome passivated.  
1.4 Some chromium-free passivates are being used commercially. Although these products will test negative for hexavalent chromium, they may interfere with cleaning and pretreating. Chromium bearing passivates that contain film forming constituents such as acrylic resins are also being commercially applied. The reaction of these products to the spot test will vary. Abrading the surface with emery paper will improve the likelihood of reliable detection. This technique is not recommended for acrylic resin containing passivation treatments.  
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.6 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.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization establis...

General Information

• Status: Published
• Publication Date: 31-May-2022
• ICS: 25.220.40 - Metallic coatings
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.53 - Coil Coated Metal

Relations

• Refers: ASTM D5723-95(2019) - Standard Practice for Determination of Chromium Treatment Weight on Metal Substrates by X-Ray Fluorescence
• Effective Date: 01-Dec-2019
• Refers: ASTM D5723-95(2015) - Standard Practice for Determination of Chromium Treatment Weight on Metal Substrates by X-Ray Fluorescence
• Effective Date: 01-Jul-2015
• Refers: ASTM D5723-95(2010) - Standard Practice for Determination of Chromium Treatment Weight on Metal Substrates by X-Ray Fluorescence
• Effective Date: 01-Jun-2010
• Refers: ASTM D5723-95(2002) - Standard Practice for Determination of Chromium Treatment Weight on Metal Substrates by X-Ray Fluorescence
• Effective Date: 15-May-1995
• Refers: ASTM D2092-95 - Standard Guide for Preparation of Zinc-Coated (Galvanized) Steel Surfaces for Painting
• Effective Date: 15-Apr-1995
• Refers: ASTM D5723-95 - Standard Practice for Determination of Chromium Treatment Weight on Metal Substrates by X-Ray Fluorescence
• Effective Date: 01-Jan-1995

Overview

ASTM D6492-99(2022) is the internationally recognized standard practice for the detection of hexavalent chromium on zinc and zinc/aluminum alloy coated steel. Issued by ASTM International, this standard provides a qualitative screening method for identifying the presence of chrome passivation treatments-specifically hexavalent chromium-on coated steel products. Its application is essential in industries where metal finishing, coil coating, and pretreatment processes require strict control over chemical residues to ensure product quality, safety, and environmental compliance.

Key Topics

• Hexavalent Chromium Detection: This standard details a spot test using a specific indicator solution (including 1,5-diphenylcarbohydrazide) that develops a pink color in the presence of hexavalent chromium. Detection sensitivity typically starts at 0.5 parts per million dissolved in the indicator.
• Surface Preparation and Testing: Surfaces must be clean and free of oil or dirt. Metal testing can be performed on cut panels or coil stock using specific laboratory apparatus like brown polyethylene wash bottles or glass dropper bottles.
• Range and Limitations: The procedure is intended for qualitative screening rather than quantitative measurement. While useful for distinguishing chrome-passivated from non-passivated surfaces, false negatives may occur, and additional instrumental analysis (e.g., AES, ESCA, atomic absorption) is recommended if results are inconclusive.
• Special Considerations: Chromium-free and acrylic-resin-containing passivates may affect test results. The technique is not recommended for surfaces with acrylic resin-based passivation.

Applications

• Coil Coating Lines: Ensures chrome passivation does not contaminate cleaning and pretreatment baths or interfere with subsequent processes.
• Quality Assurance in Metal Fabrication: Enables routine screening of galvanized and aluminum/zinc alloy coated steels for unwanted passivation before painting or further coating.
• Environmental and Regulatory Compliance: Fulfills requirements for monitoring and minimizing hazardous substance residues, especially hexavalent chromium, in finished steel products.
• Research and Laboratory Investigation: Provides a rapid screening technique for material scientists studying corrosion protection layers or troubleshooting surface treatment issues.

This standard is particularly relevant for:

• Steel manufacturers and coil coaters
• Metal finishing and painting facilities
• Laboratories conducting trace metal analysis
• Regulatory auditors concerned with heavy metal contamination

Related Standards

The following related ASTM standards provide additional guidance for quality and compliance in surface treatment and analysis:

• ASTM D2092: Guide for Preparation of Zinc-Coated (Galvanized) Steel Surfaces for Painting
• ASTM D5723: Practice for Determination of Chromium Treatment Weight on Metal Substrates by X-Ray Fluorescence

Practical Value

• Cost-effective screening: Allows quick detection of hexavalent chromium without the need for sophisticated instrumentation in most cases.
• Improved process control: Helps manufacturers prevent cross-contamination and maintain high-quality surface treatments.
• Enhanced safety and compliance: Assists in meeting international safety and material standards including those mandated by regulatory organizations.
• Environmental protection: Supports efforts to minimize the release of hazardous heavy metals, such as hexavalent chromium, into the environment.

Keywords: ASTM D6492, hexavalent chromium detection, zinc coated steel, zinc/aluminum alloy, chrome passivation, qualitative screening, coil coating, industrial metal testing, steel surface analysis.

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: D6492 − 99 (Reapproved 2022)
Standard Practice for
Detection of Hexavalent Chromium On Zinc and Zinc/
Aluminum Alloy Coated Steel
This standard is issued under the fixed designation D6492; 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. Scope spot test will vary.Abrading the surface with emery paper will
improve the likelihood of reliable detection. This technique is
1.1 This practice can be used to detect the presence of
not recommended for acrylic resin containing passivation
hexavalent chromium on galvanized and zinc/aluminum alloy
treatments.
coated steel surfaces. Hexavalent chromium-bearing treat-
ments (passivates) can be applied to coated steels to prevent 1.5 The values stated in SI units are to be regarded as the
storage stain. While passivated 55 % aluminum-zinc alloy standard. The values given in parentheses are for information
coated steel is commonly painted, passivated galvanized steel only.
is not. Chrome passivation may interfere with the successful
1.6 This standard does not purport to address all of the
pretreatment of galvanized steel, as well as contaminate
safety concerns, if any, associated with its use. It is the
cleaning and pretreatment baths on a coil coating line.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1.2 The amount of hexavalent chromium that will cause the
mine the applicability of regulatory limitations prior to use.
indicator to produce a discernible pink color is in the range of
1.7 This international standard was developed in accor-
0.5 parts per million dissolved in the indicator solution. It is
dance with internationally recognized principles on standard-
possible that a coated steel surface that produces a negative
ization established in the Decision on Principles for the
result does have chromium on the surface. If a material that
Development of International Standards, Guides and Recom-
yieldsanegativeresultissuspectedofhavingchromiumonthe
mendations issued by the World Trade Organization Technical
surface, instrumental methods should be used. Chrome depos-
Barriers to Trade (TBT) Committee.
its of 1 mg/ft can be easily missed by analytical instruments
such as the scanning electron microscope with energy disper-
2. Referenced Documents
sive x-ray analysis (EDXA) capability. Auger electron spec-
troscopy (AES) or electron spectroscopy for chemical analysis 2.1 ASTM Standards:
D2092 Guide for Preparation of Zinc-Coated (Galvanized)
(ESCA) can identify chemical species present in the levels
required for adequate detection. Stripping the metallic coating Steel Surfaces for Painting (Withdrawn 2008)
D5723 Practice for Determination of Chromium Treatment
and analyzing for chrome by atomic absorption or inductively
coupled plasma can also give reliable results in detecting the Weight on Metal Substrates by X-Ray Fluorescence
presence of chrome.
3. Apparatus
1.3 This practice is designed to be a qualitative means of
3.1 The following materials will be required to perform the
screening chrome passivated coils from those which are not
stripping procedure:
chrome passivated.
3.1.1 Dark colored or Brown Polyethylene Wash Bottle,
1.4 Some chromium-free passivates are being used com-
(500 mL) or brown glass dropper bottle.
mercially. Although these products will test negative for
3.1.2 TestSpecimens, which may be cut panels or coil stock.
hexavalent chromium, they may interfere with cleaning and
pretreating. Chromium bearing passivates that contain film 4. Reagents
forming constituents such as acrylic resins are also being
4.1 Thefollowingchemicalreagentsarerequiredtoperform
commercially applied. The reaction of these products to the
this procedure:
1 2
This practice is under the jurisdiction of ASTM Committee D01 on Paint and For referenced ASTM standards, visit the ASTM website, www.astm.org, or
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