ASTM B695-00
(Specification)Standard Specification for Coatings of Zinc Mechanically Deposited on Iron and Steel
Standard Specification for Coatings of Zinc Mechanically Deposited on Iron and Steel
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 [mu]m. The seven thickest classes are usually referred to as "mechanically galvanized."
1.2 This standard does not purport to address the safety problems 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. Note 1-The performance of this coating complies with the requirements of Specification A153 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 may be approximate.
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Designation: B 695 – 00
Standard Specification for
Coatings of Zinc Mechanically Deposited on Iron and Steel
This standard is issued under the fixed designation B 695; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope B 242 Practice for Preparation of High-Carbon Steel for
Electroplating
1.1 This specification covers the requirements for a coating
B 322 Practice for Cleaning Metals Prior to Electroplating
of zinc mechanically deposited on iron and steel basis metals.
B 487 Test Method for Measurement of Metal and Oxide
The coating is provided in several thicknesses up to and
Coating Thicknesses by Microscopical Examination of a
including 107 μm. The seven thickest classes are usually
Cross Section
referred to as “mechanically galvanized.”
B 499 Test Method for Measurement of Coating Thick-
1.2 This standard does not purport to address all of the
nesses by the Magnetic Method: Nonmagnetic Coatings on
safety concerns, if any, associated with its use. It is the
Magnetic Basis Metals
responsibility of the user of this standard to establish appro-
B 571 Test Methods for Adhesion of Metallic Coatings
priate safety and health practices and determine the applica-
B 602 Test Method for Attribute Sampling of Metallic and
bility of regulatory limitations prior to use.
Inorganic Coatings
NOTE 1—The performance of this coating complies with the require-
F 1470 Guide for Fastener Sampling for Specified Mechani-
ments of Specification A 153 and MIL-C-81562.
cal Properties and Performance Inspection
1.3 The values stated in SI units are to be regarded as the
2.2 Military Standard:
standard. The inch-pound equivalents of SI units may be
MIL-C-81562 Coating, Cadmium, Tin Cadmium and Zinc
approximate.
(Mechanically Deposited)
2.3 AISC Standard:
2. Referenced Documents
Specifications for Structural Joints Using ASTM A 325 or
2.1 ASTM Standards:
A 490 Bolts
A 153 Specification for Zinc Coating (Hot–Dip) on Iron and
3. Classification
Steel Hardware
A 194/A194M Specification for Carbon and Alloy Steel
3.1 Classes—Zinc coatings are classified on the basis of
Nuts for Bolts for High-Pressure and High-Temperature
thickness, as follows:
Service
Class Minimum Thickness, μm
110 107
A 325 Specification for Structural Bolts, Steel, Heat
4 80 81
Treated, 120/105 ksi Minimum Tensile Strength
70 69
A 490 Specification for Heat-Treated, Steel Structural
65 66
Bolts, 150 ksi Minimum Tensile Strength 55 53
4 50 50
A 563 Specification for Carbon and Alloy Steel Nuts
40 40
B 117 Practice for Operating Salt Spray (Fog) Apparatus
25 25
12 12
B 183 Practice for Preparation of Low-Carbon Steel for
6 88
Electroplating
3.2 Types—Zinc coatings are identified by types on the
This specification is under the jurisdiction of ASTM Committee B-8 on
basis of supplementary treatment required, as follows:
Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee
B08.08.04 on Light Metals.
Current edition approved March 10, 2000. Published May 2000. Originally
published as B 695 – 82. Last previous edition B 695 – 91 (1997).
2 7
Annual Book of ASTM Standards, Vol 01.06. Annual Book of ASTM Standards, Vol 01.08.
3 8
Annual Book of ASTM Standards, Vol 01.01. Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
Annual Book of ASTM Standards, Vol 15.08. Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
5 9
Annual Book of ASTM Standards, Vol 03.02. Available from American Institute of Steel Construction, Inc., 400 N. Michigan
Annual Book of ASTM Standards, Vol 02.05. Ave., Chicago, IL 60611.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B 695
Type I—As coated, without supplementary treatment (Ap- with Practice B 242. In general, nonelectrolytic alkaline,
pendix X2.1). anodic-alkaline, and some inhibited acid cleaners are preferred
Type II—With colored chromate conversion treatment (Ap- to avoid the risk of producing hydrogen embrittlement from the
pendix X2.2). cleaning procedure.
6.2.3 For low-carbon steels, see Practice B 183. Useful
4. Ordering Information
guidelines are also given in Practice B 322.
4.1 To make the application of this standard complete, the
6.2.4 Mechanical deposition of zinc coatings shall consist,
purchaser should supply the following information to the seller
in general, of all of the steps listed below, and in the sequence
in the purchase order or other governing document:
as shown:
4.1.1 Class, including a maximum thickness, if appropriate,
6.2.4.1 Preparation of the surface of the parts to be coated,
type, and for Type II, color and need for supplemental lubricant
by chemical (generally acidic) procedure to an extent that
(3.1, 3.2, and 6.2.5),
permits uniformly satisfactory results from subsequent steps.
4.1.2 Nature of substrate (for example, high-strength steel),
6.2.4.2 Deposition of a thin metal coating, generally of
need for stress relief (6.2.1), and cleaning precautions to be
copper, by immersion in appropriate chemical solutions, with-
followed (6.2.2 and 6.2.3),
out the use of electric current. There are no thickness require-
4.1.3 Significant surfaces (6.3),
ments for this coating.
4.1.4 Requirements for and methods of testing for one or
6.2.4.3 Tumbling of the parts that have been treated accord-
more of the following, if required: need for and type of test
ing to 6.2.4.1 and 6.2.4.2 in a container with the following:
specimens (8.1), thickness (6.3 and 8.3), adhesion (6.4 and
(i) the zinc metal to be deposited, in powder form;
8.4), corrosion resistance (6.5 and 8.5), absence of hydrogen
(ii) impact media, which may be glass or other substances
embrittlement, and the waiting period before testing and testing
that are essentially inert to the chemicals of the deposition
loads (6.6 and 8.6),
process. The function of this media is to aid in providing
4.1.5 Inspection responsibility (Section 11) and sampling
mechanical forces to drive the metal powder onto the substrate
plan for each inspection criterion (Section 7), and
parts;
4.1.6 Requirements for certified report of test results (Sec-
(iii) a “promoter” or “accelerator” which aids in the uniform
tion 10).
deposition of the metal powder;
5. Workmanship (iv) a liquid medium, generally water.
6.2.4.4 Separation of the parts from the solid and liquid
5.1 The coating shall be uniform in appearance and substan-
media.
tially free of blisters, pits, nodules, flaking, and other defects
6.2.4.5 Rinsing.
that can adversely affect the function of the coating. The
6.2.4.6 Drying.
coating shall cover all surfaces as stated in 6.3 including roots
6.2.5 Supplementary Treatments:
of threads, thread peaks, corners, recesses, and edges. The
coating shall not be stained or discolored throughout to an 6.2.5.1 Colored Chromate Conversion Treatments (Type
II)—Colored chromate conversion treatment for Type II shall
extent that would adversely affect appearance as a functional
requirement. However, superficial staining, that results from be done in a solution containing hexavalent chromium ions.
This solution shall produce a bright or semi-bright continuous,
rinsing or drying, and variations in color or luster shall not be
cause for rejection. smooth, protective film with a uniform color that may range
from yellow through bronze and olive-drab to brown and black
NOTE 2—The nature of the mechanical plating process is such that
and that may be dyed to a desired color. Bright dips that do not
coatings characteristically will not be as smooth or as bright as some
contain salts that yield films containing hexavalent chromium
electroplated coatings.
ions are not permitted as treatments for producing Type II
6. Requirements
coatings.
6.2.5.2 Waxes, lacquers, or other organic coatings may be
6.1 Appearance—The coating as deposited shall have a
used to improve lubricity, and the need for them shall be
uniform silvery appearance, and a matte to medium-bright
supplied in the purchase order or other governing document
luster.
6.2 Process: (see 4.1.1). Supplemental lubrication treatments shall not be
used to ensure conformance to the salt spray corrosion resis-
6.2.1 Stress-Relief Treatment—All steel parts that have an
ultimate tensile strength of 1000 MPa and above and that tance requirements (see 8.5.4).
contain tensile stresses caused by machining, grinding, 6.2.5.3 Lubrication of grade DH nuts processed in accor-
straightening, or cold-forming operation shall be given a dance with this specification and used with Specification A 325
stress-relief heat treatment prior to cleaning and metal deposi- high-strength bolts is a requirement of paragraph 6.5 of
tion. The temperature and time at temperature shall be 190 6 Specification A 325 and paragraph 4.8 of Specification A 563.
15°C for a minimum of3hso that maximum stress relief is
NOTE 3—Although not included in Specification A 194/A 194M, this
obtained without reducing the hardness below the specified
provision should apply to mechanically galvanized A 194 2H nuts when
minimum.
supplied for use with Specification A 325 bolts.
6.2.2 High-strength steels (which become embrittled when
NOTE 4—Specifications for structural joints using Specification A 325
charged with hydrogen) and that have heavy oxide or scale
or A 490 bolts references the use of lubricants on nuts to be used with
shall be cleaned before application of the coating in accordance Specification A 325 high-strength bolts and is found in the commentary on
B 695
this RCSC (Research Council on Structural Connections of the Engineer-
6.5 Corrosion Resistance:
ing Foundation) Specification, within the paragraphs entitled “Effect Of
6.5.1 The presence of corrosion products visible to the
Galvanizing Upon Torque Involved In Tightening” and “Shipping Re-
unaided eye at normal reading distance at the end of the
quirements For Galvanized Bolts and Nuts,” published November 1985,
specified test periods stated in Table 1 shall constitute failure,
page 30.
except that corrosion products at edges of specimens shall not
6.2.6 Surface Defects—Defects and variations in appear-
constitute failure. Slight “whisps” of white corrosion, as
ance in the coating that arise from surface conditions of the
opposed to obvious accumulations, shall be acceptable.
substrate (scratches, pores, roll marks, inclusions, etc.) and that
NOTE 8—Mechanical deposition is exclusively a barrel-finishing pro-
persist in the finish despite the observance of good metal
cess. It is recognized that mechanical deposition on parts may therefore
finishing practices shall not be cause for rejection.
produce surfaces that have a different characteristic from those on parts
NOTE 5—Applied finishes generally perform better in service when the
that are finished exclusively by racking. Similarly, corrosion testing of
substrate over which they are applied is smooth and free of torn metal,
actual parts may produce different results from those on test panels. Salt
inclusions, pores, and other defects. It is recommended that the specifi-
spray requirements that are appropriate to indicate the technical quality
cations covering the unfinished product provide limits for these defects. A
with which a process is carried out may be impractical for acceptance of
metal finisher can often remove defects through special treatments, such actual parts. In such cases the purchaser shall indicate his requirements on
as grinding, polishing, abrasive blasting, chemical treatments, and elec- the purchase order (4.1.4).
tropolishing. However, these are not normal in the treatment steps NOTE 9—In many instances, there is no direct relation between the
preceding the application of the finish. When desired they must be results of an accelerated corrosion test and the resistance to corrosion in
specified on the purchase order (4.1.2). other media, because several factors that influence the progress of
corrosion, such as the formation of protective films, vary greatly with the
6.3 Thickness:
conditions encountered. The results obtained in the test should not,
6.3.1 The thickness of the coating everywhere on the
therefore, be regarded as a direct guide to the corrosion resistance of the
significant surfaces shall be at least that of the specified class
tested materials in all environments where these materials may be used.
as defined in 3.1.
Also, performance of different materials in the test cannot always be taken
6.3.2 Significant surfaces are defined as those normally as a direct guide to the relative corrosion resistance of these materials in
service.
visible (directly or by reflection) that are essential to the
appearance or serviceability of the article when assembled in
6.5.2 On parts with Type II coatings, the greater number of
normal position; or that can be the source of corrosion products
hours for either white corrosion products or rust shall apply.
that deface visible surfaces on the assembled article. When
For example, for Type II, Class 8, the test shall be continued
necessary, the significant surfaces shall be indicated on the
until the 72-h requirement is met for white corrosion products;
drawing for the article, or by the provision of suitably marked
similarly, for Type II, Class 25, if no white corrosion products
samples.
appear before 72 h, test shall be continued until the 192-h
requirement for basis metal corrosion is met (8.5.2).
NOTE 6—The thickness of mechanically-deposited coatings varies from
point-to-point on the surface of a product, characteristically tending to be 6.6 Absence of Hydrogen Embrittlement—Springs and other
thicker on flat surfaces and thinner at exposed edges, sharp projections,
high-strength parts subject to flexure shall be held for a
shielded or recessed areas, interior corners and holes, with such thinner
minimum of 48 h at room temperature after coating before
areas often being exempted from thickness requirements.
being loaded, flexed, or used. Such high-strength steel parts
6.3.3 When significant surfaces are involved on which the
shall be free of hydrogen embrittlement. When specified in the
specified thickness of deposit cannot readily be controlled, the
purchase order, freedom from embrittlement shall be deter-
purchaser and manufacturer should recognize the necessity for
mined by the test specified herein (4.1.4 and 8.6).
either thicker or thinner deposits. For example, to reduce
buildup in thread roots, holes, deep r
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