ASTM D6492-99(2011)
(Practice)Standard Practice for Detection of Hexavalent Chromium On Zinc and Zinc/Aluminum Alloy Coated Steel
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D6492 − 99(Reapproved 2011)
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 and health practices and determine the applica-
1.2 The amount of hexavalent chromium that will cause the
bility of regulatory limitations prior to use.
indicator to produce a discernible pink color is in the range of
0.5 parts per million dissolved in the indicator solution. It is
2. Referenced Documents
possible that a coated steel surface that produces a negative
result does have chromium on the surface. If a material that
2.1 ASTM Standards:
yieldsanegativeresultissuspectedofhavingchromiumonthe
D2092 Guide for Preparation of Zinc-Coated (Galvanized)
surface, instrumental methods should be used. Chrome depos-
Steel Surfaces for Painting (Withdrawn 2008)
its of 1 mg/ft can be easily missed by analytical instruments
D5723 Practice for Determination of Chromium Treatment
such as the scanning electron microscope with energy disper-
Weight on Metal Substrates by X-Ray Fluorescence
sive x-ray analysis (EDXA) capability. Auger electron spec-
troscopy (AES) or electron spectroscopy for chemical analysis 3. Apparatus
(ESCA) can identify chemical species present in the levels
3.1 The following materials will be required to perform the
required for adequate detection. Stripping the metallic coating
stripping procedure:
and analyzing for chrome by atomic absorption or inductively
3.1.1 Dark colored or Brown Polyethylene Wash Bottle,
coupled plasma can also give reliable results in detecting the
(500 mL) or brown glass dropper bottle.
presence of chrome.
3.1.2 TestSpecimens, which may be cut panels or coil stock.
1.3 This practice is designed to be a qualitative means of
4. Reagents
screening chrome passivated coils from those which are not
chrome passivated.
4.1 Thefollowingchemicalreagentsarerequiredtoperform
this procedure:
1.4 Some chromium-free passivates are being used com-
4.1.1 1,5-Diphenylcarbohydrazide.
mercially. Although these products will test negative for
4.1.2 Acetone.
hexavalent chromium, they may interfere with cleaning and
4.1.3 Ethanol, 85 %.
pretreating. Chromium bearing passivates that contain film
4.1.4 Phosphoric Acid.
forming constituents such as acrylic resins are also being
4.1.5 Distilled Water.
commercially applied. The reaction of these products to the
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
Related Coatings, Materials, and Applications and is the direct responsibility of contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Subcommittee D01.53 on Coil Coated Metal. Standards volume inf
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