1、Designation: B696 00 (Reapproved 2015)Standard Specification forCoatings of Cadmium Mechanically Deposited1This standard is issued under the fixed designation B696; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. A number in parentheses indicates the year of last reapproval. Asuperscript 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. Scope1.1 This specification covers the requirem
3、ents for a coatingof cadmium mechanically deposited on metal products. Thecoating is provided in various thicknesses up to and including12 m.1.2 Mechanical deposition greatly reduces the risk of hy-drogen embrittlement and is suitable for coating bores andrecesses in many parts that cannot be conven
4、iently electro-plated (see Appendix X3).1.3 Cadmium coatings are usually applied to provide engi-neering properties and corrosion resistance. The performanceof a cadmium coating depends largely on its thickness and thekind of environment to which it is exposed. Without proof ofsatisfactory correlati
5、on, accelerated tests such as the salt spray(fog) test cannot be relied upon to predict performance in otherenvironments, nor will these serve as comparative measures ofthe corrosion resistance afforded by coatings of differentmetals. Thus, although there is a marked superiority of cad-mium coatings
6、 over zinc coatings of equal thickness in the saltspray test, this is often not the case under conditions of use, sothat further testing in the service environment should beconducted.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is there
7、sponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specificprecautionary statements, see 1.5 and 1.6.1.5 WarningCadmium is toxic and must not be used in acoating for articles tha
8、t can come into contact with food orbeverages, or for dental or other equipment that can be insertedinto the mouth. Consult appropriate agencies for regulations inthis connection.1.6 WarningBecause of the toxicity of cadmium vaporsand cadmium oxide fumes, cadmium-coated articles must notbe used at t
9、emperatures of 320C and above. They must not bewelded, spot-welded, soldered, or otherwise strongly heatedwithout adequate ventilation that will efficiently remove alltoxic fumes.2. Referenced Documents2.1 ASTM Standards:2B117 Practice for Operating Salt Spray (Fog) ApparatusB183 Practice for Prepar
10、ation of Low-Carbon Steel forElectroplatingB242 Guide for Preparation of High-Carbon Steel for Elec-troplatingB322 Guide for Cleaning Metals Prior to ElectroplatingB487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination ofCross SectionB499 Test Method for Me
11、asurement of Coating Thicknessesby the Magnetic Method: Nonmagnetic Coatings onMagnetic Basis MetalsB567 Test Method for Measurement of Coating Thicknessby the Beta Backscatter MethodB602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsB697 Guide for Selection of Sampling Plans f
12、or Inspectionof Electrodeposited Metallic and Inorganic CoatingsB762 Test Method of Variables Sampling of Metallic andInorganic CoatingsF1470 Practice for Fastener Sampling for Specified Me-chanical Properties and Performance Inspection3. Classification3.1 ClassesCadmium coatings are classified on t
13、he basisof thickness, as follows:Class Minimum Thickness, m12 1288551This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct responsibility of SubcommitteeB08.06 on Soft Metals.Current edition approved March 1, 2015. Published April 2015
14、. Originallyapproved in 1981. Last previous edition approved in 2009 as B696 00(2009). DOI:10.1520/B0696-00R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the s
15、tandards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2 TypesCadmium coatings are identified by types on thebasis of supplementary treatment required, as follows:Type IAs coated without su
16、pplementary chromate treat-ment (Appendix X2.1).Type IIWith colored chromate conversion treatment (Ap-pendix X2.2).4. Ordering Information4.1 To make the application of this standard complete, thepurchaser should supply the following information to the sellerin the purchase order or other governing
17、document:4.1.1 Class, including a maximum thickness, if appropriate,Type, and for Type II, color and need for supplementallubricant (see 3.1, 3.2, and 6.2.4.2),4.1.2 Nature of substrate (for example, high-strength steel),needed for stress relief (6.2.1), and cleaning precautions to befollowed 6.2.2
18、and 6.2.3),4.1.3 Significant surfaces (6.3),4.1.4 Requirements for and methods of testing for one ormore of the following, if required: need for and type of testspecimens (8.1), thickness (6.3 and 8.3), adhesion (6.4 and8.4), corrosion resistance (6.5 and 8.5), absence of hydrogenembrittlement, and
19、the waiting period before testing and testingloads (6.6 and 8.6),4.1.5 Inspection responsibility (Supplementary Require-ment S1) and sampling plan for each inspection criterion(Section 7).4.1.6 Requirements for certified report of test results (Sec-tion 10).5. Workmanship5.1 The coating shall be uni
20、form in appearance and free ofblisters, pits, nodules, flaking, and other defects that canadversely affect the function of the coating. The coating shallcover all surfaces as stated in 6.3 including roots of threads,thread peaks, corners, recesses, and edges. The coating shallnot be stained or disco
21、lored throughout to an extent that wouldadversely affect appearance as a functional requirement.However, superficial staining that results from rinsing ordrying and variations in color or luster shall not be cause forrejection.NOTE 1The nature of the mechanical plating process is such thatcoatings c
22、haracteristically will not be as smooth or as bright as someelectroplated coatings.6. Requirements6.1 AppearanceThe coating as deposited shall have auniform silvery appearance, and a matte to medium-brightluster.6.2 Process:6.2.1 Stress-Relief TreatmentAll steel parts that have ul-timate tensile str
23、ength of 1000 MPa and above and that containtensile stresses caused by machining, grinding, straightening,or cold-forming operation shall be given a stress relief heattreatment prior to cleaning and metal deposition. The tempera-ture and time at temperature shall be 190 6 15C for aminimum of3hsothat
24、 maximum stress relief is obtainedwithout reducing the hardness below the specified minimum.6.2.2 High-strength steels that have heavy oxide or scaleshall be cleaned before application of the coating in accordancewith Practice B242. In general, nonelectrolytic alkaline,anodic-alkaline, and some inhi
25、bited acid cleaners are preferredto avoid the risk of producing hydrogen embrittlement from thecleaning procedure.6.2.3 For low-carbon steels see Practice B183. Usefulguidelines are also given in Practice B322.6.2.4 Supplementary Treatments:6.2.4.1 Colored Chromate Conversion Treatments (TypeII)Chro
26、mate treatment for Type II shall be done in a solutioncontaining hexavalent chromium. This solution shall produce abright or semi-bright continuous, smooth, protective film witha uniform color that may range from yellow through bronzeand olive drab to brown and black including olive drab and thatmay
27、 be dyed to a desired color. Post treatments that do notcontain salts that yield films containing hexavalent chromiumare not permitted as treatments for producing Type II coatings.6.2.4.2 Waxes, lacquers, or other organic coatings may beused to improve lubricity, and the need for them shall besuppli
28、ed in the purchase order or other governing document(4.1.1). Supplemental lubrication treatment shall not be used toensure conformance to the salt spray corrosion resistancerequirements.6.2.5 Surface DefectsDefects and variations in appear-ance in the coating that arise from surface conditions of th
29、esubstrate (scratches, pores, roll marks, inclusions, and so forth)and that persist in the finish despite the observance of goodmetal finishing practices shall not be cause for rejection.NOTE 2Applied finishes generally perform better in service when thesubstrate over which they are applied is smoot
30、h and free of torn metal,inclusions, pores, and other defects. It is recommended that the specifi-cations covering the unfinished product provide limits for these defects.Ametal finisher can often remove defects through special treatments, suchas grinding, polishing, abrasive blasting, chemical trea
31、tments, and elec-tropolishing. However, these are not normal in the treatment stepspreceding the application of the finish. When desired they must bespecified on the purchase order (4.1.2).6.3 Thickness:6.3.1 The thickness of the coating everywhere on thesignificant surfaces shall be at least that o
32、f the specified classas defined in 3.1.6.3.2 Significant surfaces are defined as those normallyvisible (directly or by reflection) that are essential to theappearance or serviceability of the article when assembled innormal position; or that can be the source of corrosion productsthat deface visible
33、 surfaces on the assembled article. Whennecessary, the significant surfaces shall be indicated on thedrawing for the article, or by the provision of suitably markedsamples.NOTE 3The thickness of mechanically-deposited coatings varies frompoint-to-point on the surface of a product, characteristically
34、 tending to bethicker on flat surfaces and thinner at exposed edges, sharp projections,shielded or recessed areas, interior corners and holes, with such thinnerareas often being exempted from thickness requirements.6.3.3 When significant surfaces are involved on which thespecified thickness of depos
35、it cannot readily be controlled, thepurchaser and manufacturer should recognize the necessity foreither thicker or thinner deposits. For example, to reduceB696 00 (2015)2buildup in thread roots, holes, deep recesses, bases of angles,and similar areas, the deposit thickness on the more accessiblesurf
36、aces will have to be reduced proportionately.NOTE 4The coating thickness requirement of this specification is aminimum requirement; that is, the coating thickness is required to equal orexceed the specified thickness everywhere on the significant surfaces.Variation in the coating thickness from poin
37、t to point on a coated articleis an inherent characteristic of mechanical deposition processes.Therefore, the coating thickness will have to exceed the specified value atsome points on the significant surfaces to ensure that the thickness equalsor exceeds the specified value at all points. Hence, in
38、 most cases, theaverage coating thickness on an article will be greater than the specifiedvalue; how much greater is largely determined by the shape of the articleand the characteristics of the deposition process. In addition, the averagecoating thickness on articles will vary from article to articl
39、e within aproduction lot. Therefore, if all of the articles in a production lot are tomeet the thickness requirement, the average coating thickness for theproduction lot as a whole will be greater than the average necessary toensure that a single article meets the requirement.6.4 AdhesionThe cadmium
40、 coating shall be sufficientlyadherent 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 theunaided eye at normal reading distance at the end of thespecified test periods stated in Table 1 shall constitute failure,excep
41、t that corrosion products at edges of specimens shall notconstitute failure. Slight “wisps” of white corrosion, as op-posed to obvious accumulations, shall be acceptable.NOTE 5The hours given in Table 1 are the minimums required toguarantee satisfactory performance. Longer periods before the appeara
42、nceof white corrosion products and rust are possible, but salt spray resistancedoes not vary in exact proportion with increased plating thickness. Thehours given for Type II reflect the added protection of chromate treatmentswithout requiring impractical testing periods.6.5.2 There are no requiremen
43、ts for corrosion of basismetals other than steels.NOTE 6Mechanical deposition is exclusively a barrel-finishing pro-cess. It is recognized that mechanical deposition on parts may thereforeproduce surfaces that have a different characteristic from those on partsthat are finished exclusively by rackin
44、g. Similarly, corrosion testing ofactual parts may produce different results from those on test panels. Saltspray requirements that are appropriate to indicate the technical qualitywith which a process is carried out may be impractical for acceptance ofactual parts. In such cases the purchaser shoul
45、d indicate his requirementson the purchaser order (4.1.4).NOTE 7In many instances, there is no direct relation between theresults of an accelerated corrosion test and the resistance to corrosion inother media, because several factors that influence the progress ofcorrosion, such as the formation of
46、protective films, vary greatly with theconditions encountered. The results obtained in the test should not,therefore, be regarded as a direct guide to the corrosion resistance of thetested materials in all environments where these materials may be used.Also, performance of different materials in the
47、 test cannot always be takenas a direct guide to the relative corrosion resistance of these materials inservice.6.5.3 On parts with Type II coatings, the greater number ofhours for either white corrosion products or rust shall apply.For example, for Type II, Class 5, the test shall be continueduntil
48、 the 72-h requirement is met for white corrosion products;similarly, for Type II, Class 8, if no white corrosion productsappear before 72 h, the test shall be continued until the 96-hrequirement for basis metal corrosion is met (8.5.2).6.6 Absence of Hydrogen EmbrittlementSteel springs andother high
49、-strength steel parts subject to flexure shall be heldfor a minimum of 48 h at room temperature after coating beforebeing loaded, flexed, or used. Such high-strength steel partsshall be free of hydrogen embrittlement. When specified in thepurchase order, freedom from embrittlement shall be deter-mined by the test specified herein (4.1.4 and 8.6).7. Sampling7.1 The purchaser and producer are urged to employ statis-tical process control in the coating process. Properlyperformed, statistical process control will assure coated prod-ucts of satisfactory quality and
