ASTM B695-21

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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: B695 − 04 (Reapproved 2016) B695 − 21
Standard Specification for
Coatings of Zinc Mechanically Deposited on Iron and Steel
This standard is issued under the fixed designation B695; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope Scope*
1.1 This specification covers the requirements for a coating of zinc mechanically deposited on iron and steel basis metals. The
coating is provided in several thicknesses up to and including 107 μm. The seven thickest classes are usually referred to as
“mechanically galvanized.”
1.2 Units—The values stated in SI units are to be regarded as the standard. The inch-pound equivalents of SI units are given for
informational purposes.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
NOTE 1—The performance of this coating complies with the requirements of Specification A153/A153M and MIL-C-81562.
1.3 The values stated in SI units are to be regarded as the standard. The inch-pound equivalents of SI units are given for
informational purposes.
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
2.1 ASTM Standards:
A153/A153M Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware
A194/A194M Specification for Carbon Steel, Alloy Steel, and Stainless Steel Nuts for Bolts for High Pressure or High
Temperature Service, or Both
A325 Specification for Structural Bolts, Steel, Heat Treated, 120/105 ksi Minimum Tensile Strength (Withdrawn 2016)
A490 Specification for Structural Bolts, Alloy Steel, Heat Treated, 150 ksi Minimum Tensile Strength (Withdrawn 2016)
A563A563/A563M Specification for Carbon and Alloy Steel Nuts (Metric) A0563_A0563M (Inch and Metric)
B117 Practice for Operating Salt Spray (Fog) Apparatus
B183 Practice for Preparation of Low-Carbon Steel for Electroplating
This specification is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.06 on Soft
Metals.
Current edition approved Nov. 1, 2016Nov. 1, 2021. Published November 2016November 2021. Originally approved in 1982. Last previous edition approved in 20092016
as B695B695 – 04– 04(2009).(2016). DOI: 10.1520/B0695-04R16.10.1520/B0695-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. 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
B695 − 21
B242 Guide for Preparation of High-Carbon Steel for Electroplating
B322 Guide for Cleaning Metals Prior to Electroplating
B487 Test Method for Measurement of Metal and Oxide Coating Thickness by Microscopical Examination of Cross Section
B499 Test Method for Measurement of Coating Thicknesses by the Magnetic Method: Nonmagnetic Coatings on Magnetic Basis
Metals
B571 Practice for Qualitative Adhesion Testing of Metallic Coatings
B602 Guide for Attribute Sampling of Metallic and Inorganic Coatings
B697 Guide for Selection of Sampling Plans for Inspection of Electrodeposited Metallic and Inorganic Coatings
B762 Guide of Variables Sampling of Metallic and Inorganic Coatings
F1470 Practice for Fastener Sampling for Specified Mechanical Properties and Performance Inspection
F3125/F3125M Specification for High Strength Structural Bolts and Assemblies, Steel and Alloy Steel, Heat Treated, Inch
Dimensions 120 ksi and 150 ksi Minimum Tensile Strength, and Metric Dimensions 830 MPa and 1040 MPa Minimum
Tensile Strength
2.2 Military Standard:
MIL-C-81562 Coating, Cadmium, Tin Cadmium and Zinc (Mechanically Deposited)
2.3 AISC Standard:
Specifications for Structural Joints Using ASTM A325 or A490 Bolts
3. Classification
3.1 Classes—Zinc coatings are classified on the basis of thickness, as follows:
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098
B695 − 21
Class Minimum Thickness, μm
110 107
80 81
70 69
65 66
55 53
50 50
40 40
25 25
12 12
8 8
5 5
3.2 Types—Zinc coatings are identified by types on the basis of supplementary treatment required, as follows:
Type I—As coated, without supplementary treatment (Appendix (X2.1).
Type II—With colored chromate conversion treatment (Appendix (X2.2).
4. Ordering Information
4.1 Supplying the following information by the purchaser to the seller in the purchase order or other governing document will
make the application of this specification complete:
4.1.1 Class, including a maximum thickness, if appropriate, type, and for Type II, color and need for supplemental lubricant (3.1,
3.2, and 6.2.5),
4.1.2 Nature of substrate (for example, high-strength steel), need for stress relief (6.2.1), and cleaning precautions to be followed
(6.2.2 and 6.2.3),
4.1.3 Significant surfaces (6.3),
4.1.4 Requirements for and methods of testing for one or more of the following, if required: need for and type of test specimens
(8.1), thickness (6.3 and 8.3), adhesion (6.4 and 8.4), corrosion resistance (6.5 and 8.5), absence of hydrogen embrittlement, and
the waiting period before testing and testing loads (6.6 and 8.6),
4.1.5 Inspection responsibility (Section 11) and sampling plan for each inspection criterion (Section 7), and
4.1.6 Requirements for certified report of test results (Section 10).
5. Workmanship
5.1 The coating shall be uniform in appearance and free of blisters, pits, nodules, flaking, and other defects that are capable of
adversely affecting the function of the coating. The coating shall cover all surfaces as stated in 6.3, including roots of threads,
thread peaks, corners, recesses, and edges. The coating shall not be stained or discolored throughout to an extent capable of
adversely affecting appearance as a functional requirement. However, superficial staining, that results from rinsing or drying, and
variations in color or luster shall not be cause for rejection.
NOTE 2—The nature of the mechanical plating process is such that coatings characteristically will not be as smooth or as bright as some electroplated
coatings.
6. Requirements
6.1 Appearance—The coating as deposited shall have a uniform silvery appearance, and a matte to medium-bright luster.
6.2 Process:
6.2.1 Stress-Relief Treatment—All steel parts that have an ultimate tensile strength of 1000 MPa and above and that contain tensile
stresses caused by machining, grinding, straightening, or cold-forming operation shall be given a stress-relief heat treatment prior
to cleaning and metal deposition. The temperature and time at temperature shall be 190 6 15°C15 °C for a minimum of 3 h so
that maximum stress relief is obtained without reducing the hardness below the specified minimum.
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6.2.2 High-strength steels (which become embrittled when charged with hydrogen) and that have heavy oxide or scale shall be
cleaned before application of the coating in accordance with Practice B242. In general, nonelectrolytic alkaline, anodic-alkaline,
and some inhibited acid cleaners are preferred to avoid the risk of producing hydrogen embrittlement from the cleaning procedure.
6.2.3 For low-carbon steels, see Practice B183. Useful guidelines are also given in Guide B322.
6.2.4 Mechanical deposition of zinc coatings shall consist, in general, of all of the steps listed below, and in the sequence as shown:
6.2.4.1 Preparation of the surface of the parts to be coated, by chemical (generally acidic) procedure to an extent that permits
uniformly satisfactory results from subsequent steps.
6.2.4.2 Deposition of a thin metal coating, generally of copper, by immersion in appropriate chemical solutions, without the use
of electric current. There are no thickness requirements for this coating.
6.2.4.3 Tumbling of the parts that have been treated according to 6.2.4.1 and 6.2.4.2 in a container with the following:
(1) The zinc metal to be deposited, in powder form;
(2) Impact media, which includes glass, for example, or other substances that are essentially inert to the chemicals of the
deposition process. The function of this media is to aid in providing mechanical forces to drive the metal powder onto the substrate
parts;
(3) A “promoter” or “accelerator” which aids in the uniform deposition of the metal powder; and
(4) A liquid medium, generally water.
6.2.4.4 Separation of the parts from the solid and liquid media.
6.2.4.5 Rinsing.
6.2.4.6 Drying.
6.2.5 Supplementary Treatments:
6.2.5.1 Colored Chromate Conversion Treatments (Type II)—Colored chromate conversion treatment for Type II shall be done in
a solution containing hexavalent chromium ions. This solution shall produce a bright or semi-bright continuous, smooth, protective
film with a uniform color that is capable of ranging from yellow through bronze and olive-drab to brown and black and that are
capable of being dyed to a desired color. Bright dips that do not contain salts that yield films containing hexavalent chromium ions
are precluded as treatments for producing Type II coatings.
6.2.5.2 Waxes, lacquers, or other organic coatings are not prohibited from being used to improve lubricity, and the need for them
shall be supplied may be applied as a supplemental finish for added lubrication or friction modification. Any requirement for
supplemental finish shall be specified by the purchaser in the purchase order or other governing document (see 4.1.1).
Supplemental lubrication treatments shall not be used to ensure conformance to the salt spray corrosion resistance requirements
(see 8.5.4).
6.2.5.3 Lubrication of gradeNuts, notably, Specification A563/A563M DH nuts processedor Specification A194/A194M 2H, that
are coated in accordance with this specification and used with intended for use in structural bolting per Specification
A325F3125/F3125M high-strength bolts shall be supplied with a lubricant (that is, supplemental finish as described in 6.2.5.2is
a requirement of paragraph 6.5 of ), that is both clean and dry to the touch, and shall satisfy all the requirements in Specification
A325F3125/F3125M and paragraph 4.8 of Specification relative to lubrication and rotational capacity. A563.
NOTE 3—Although not included in Specification A194/A194M, this provision should apply to mechanically galvanized Specification A194/A194M 2H
nuts when supplied for use with Specification A325 bolts.
NOTE 4—Specifications for structural joints using Specification A325 or A490 bolts references the use of lubricants on nuts to be used with Specification
A325 high-strength bolts and is found in the commentary on this RCSC (Research Council on Structural Connections of the Engineering Foundation)
Specification, within the paragraphs entitled “Effect Of Galvanizing Upon Torque Involved In Tightening” and “Shipping Requirements For Galvanized
Bolts and Nuts,” published November 1985, page 30.
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6.2.6 Surface Defects—Defects and variations in appearance in the coating that arise from surface conditions of the substrate
(scratches, pores, roll marks, inclusions, etc.) and that persist in the finish despite the observance of good metal finishing practices
shall not be cause for rejection.
NOTE 3—Applied finishes generally perform better in service when the substrate over which they are applied is smooth and free of torn metal, inclusions,
pores, and other defects. It is recommended that the specifications covering the unfinished product provide limits for these defects. A metal finisher can
often remove defects through special treatments, such as grinding, polishing, abrasive blasting, chemical treatments, and electropolishing. However, these
are not normal in the treatment steps preceding the application of the finish. When desired they must be specified on the purchase order (4.1.2).
6.3 Thickness:
6.3.1 The thickness of the coating everywhere on the significant surfaces shall be at least that of the specified class as defined in
3.1.
6.3.2 Significant surfaces are defined as those normally visible (directly or by reflection) that are essential to the appearance or
serviceability of the article when assembled in normal position; or that are capable of providing the source of corrosion products
that deface visible surfaces on the assembled article. When necessary, the significant surfaces shall be indicated on the drawing
for the article, or by the provision of suitably marked samples.
NOTE 4—The thickness of mechanically-deposited coatings varies from point-to-point on the surface of a product, characteristically tending to be thicker
on flat surfaces and thinner at exposed edges, sharp projections, shielded or recessed areas, interior corners and holes, with such thinner areas often being
exempted from thickness requirements.
6.3.3 When significant surfaces are involved on which the specified thickness of deposit cannot readily be controlled, it is
incumbent upon the purchaser and manufacturer to recognize the necessity for either thicker or thinner deposits. For example, to
reduce buildup in thread roots, holes, deep recesses, bases of angles, and similar areas, the deposit thickness on the more accessible
surfaces will have to be reduced proportionately.
NOTE 5—The coating thickness requirement of this specification is a minimum requirement; that is, the coating thickness is required to equal or exceed
the specified thickness everywhere on the significant surfaces. Variation in the coating thickness from point to point on a coated article is an inherent
characteristic of mechanical deposition processes. Therefore, the coating thickness will have to exceed the specified value at some points on the significant
surfaces to ensure that the thickness equals or exceeds the specified value at all points. Hence, in most cases, the average coating thickness on an article
will be greater than the specified value; how much greater is largely determined by the shape of the article and the characteristics of the deposition process.
In addition, the average coating thickness on articles will vary from article to article within a production lot. Therefore, if all of the articles in a
production lot are to meet the thickness requirement, the average coating thickness for the production lot as a whole will be greater than the average
necessary to ensure that a single article meets the requirement.
6.4 Adhesion—The zinc coating shall be sufficiently adherent to the basis metal to pass the tests specified in 8.4.
6.5 Corrosion Resistance:
6.5.1 The presence of corrosion products visible to the unaided eye at normal reading distance at the end of the specified test
periods stated in Table 1 shall constitute failure, except that corrosion products at edges of specimens shall not constitute failure.
Slight “whisps” of white corrosion, as opposed to obvious accumulations, shall be acceptable.
TABLE 1 Minimum Hours to Failure
(White Corrosion Products and Red Rust for Mechanically
Deposited Zinc Coatings on Iron and Steel)
Type White Corrosion
Class: 55–110 50 40 25 12 8 5
A A A A A A A
I
II 72 72 72 72 72 72 72
Red Rust
Class: 55–110 50 40 25 12 8 5
I no requirement 300 250 192 96 56 36
II no requirement 300 250 192 96 72 72
A
No requirement.
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NOTE 6—Mechanical deposition is exclusively a barrel-finishing process. It is recognized that mechanical deposition on parts may therefore produce
surfaces that have a different characteristic from those on parts that are finished exclusively by racking. Similarly, corrosi
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