1、Designation: B 696 00 (Reapproved 2004)e1Standard Specification forCoatings of Cadmium Mechanically Deposited1This standard is issued under the fixed designation B 696; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st revision. A number in parentheses indicates the year of last reapproval. Asuperscript 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.e1NOTEThe Warning notes in 1.5 and 1.6 were editor
3、ially updated in October 2004.1. Scope1.1 This specification covers the requirements 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 a
4、nd is suitable for coating bores andrecesses in many parts that cannot be conveniently 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 theki
5、nd of environment to which it is exposed. Without proof ofsatisfactory correlation, 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 di
6、fferentmetals. Thus, although there is a marked superiority of cad-mium coatings 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
7、 address all of thesafety concerns, if any, associated with its use. It is theresponsibility 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
8、.6.1.5 WarningCadmium is toxic and must not be used in acoating for articles that 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 cad
9、mium vaporsand cadmium oxide fumes, cadmium-coated articles must notbe used at temperatures 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
10、:2B 117 Practice for Operating Salt Spray (Fog) ApparatusB 183 Practice for Preparation of Low-Carbon Steel forElectroplatingB 242 Practice for Preparation of High-Carbon Steel forElectroplatingB 322 Practice for Cleaning Metals Prior to ElectroplatingB 487 Test Method for Measurement of Metal and O
11、xideCoating Thicknesses by Microscopical Examination of aCross SectionB 499 Test Method for Measurement of Coating Thick-nesses by the Magnetic Method: Nonmagnetic Coatings onMagnetic Basis MetalsB 567 Test Method for Measurement of Coating Thicknessby the Beta Backscatter MethodB 602 Test Method fo
12、r Attribute Sampling of Metallic andInorganic CoatingsB 697 Guide for Selection of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorganic CoatingsB 762 Test Method of Variables Sampling of Metallic andInorganic CoatingsF 1470 Guide for Fastener Sampling for Specified Mechani-cal Pro
13、perties and Performance Inspection3. Classification3.1 ClassesCadmium coatings are classified on the 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
14、 of SubcommitteeB08.08.04 on Soft Metals.Current edition approved Oct. 1, 2004. Published October 2004. Originallyapproved in 1981. Last previous edition approved in 2000 as B 696 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.
15、org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2 TypesCadmium coatings are identified by types on thebasis o
16、f supplementary treatment required, as follows:Type IAs coated without supplementary 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 fol
17、lowing information to the sellerin the purchase order or other governing 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
18、 for stress relief (6.2.1), and cleaning precautions to befollowed 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 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), c
19、orrosion resistance (6.5 and 8.5), absence of hydrogenembrittlement, and 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
20、 of test results (Sec-tion 10).5. Workmanship5.1 The coating shall be uniform 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 peak
21、s, corners, recesses, and edges. The coating shallnot be stained or discolored throughout to an extent that wouldadversely affect appearance as a functional requirement. How-ever, superficial staining that results from rinsing or drying andvariations in color or luster shall not be cause for rejecti
22、on.NOTE 1The nature of the mechanical plating process is such thatcoatings characteristically 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:
23、6.2.1 Stress-Relief TreatmentAll steel parts that haveultimate tensile strength of 1000 MPa and above and thatcontain tensile stresses caused by machining, grinding,straightening, or cold-forming operation shall be given a stressrelief heat treatment prior to cleaning and metal deposition.The temper
24、ature and time at temperature shall be 190 6 15Cfor a minimum of3hsothat 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 B
25、 242. In general, nonelectrolytic alkaline,anodic-alkaline, and some inhibited acid cleaners are preferredto avoid the risk of producing hydrogen embrittlement from thecleaning procedure.6.2.3 For low-carbon steels see Practice B 183. Usefulguidelines are also given in Practice B 322.6.2.4 Supplemen
26、tary Treatments:6.2.4.1 Colored Chromate Conversion Treatments (TypeII)Chromate 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 throu
27、gh bronzeand olive drab to brown and black including olive drab and thatmay 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 coa
28、tings may beused to improve lubricity, and the need for them shall besupplied 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 variat
29、ions in appear-ance in the coating that arise from surface conditions of thesubstrate (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 perfo
30、rm better in service when thesubstrate over which they are applied is smooth 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 spec
31、ial treatments, suchas grinding, polishing, abrasive blasting, chemical treatments, 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 o
32、f the coating everywhere on thesignificant surfaces shall be at least that of 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
33、position; or that can be the source of corrosion productsthat deface visible 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 coatin
34、gs varies frompoint-to-point on the surface of a product, characteristically 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 Whe
35、n significant surfaces are involved on which thespecified thickness of deposit cannot readily be controlled, thepurchaser and manufacturer should recognize the necessity foreither thicker or thinner deposits. For example, to reducebuildup in thread roots, holes, deep recesses, bases of angles,B 696
36、00 (2004)e12and similar areas, the deposit thickness on the more accessiblesurfaces 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 ever
37、ywhere on the significant surfaces.Variation in the coating thickness from point to point on a coated articleis an inherent characteristic of mechanical deposition processes. There-fore, the coating thickness will have to exceed the specified value at somepoints on the significant surfaces to ensure
38、 that the thickness equals orexceeds the specified value at all points. Hence, in most cases, the averagecoating thickness on an article will be greater than the specified value;how much greater is largely determined by the shape of the article and thecharacteristics of the deposition process. In ad
39、dition, the average coatingthickness on articles will vary from article to article within a productionlot. Therefore, if all of the articles in a production lot are to meet thethickness requirement, the average coating thickness for the production lotas a whole will be greater than the average neces
40、sary to ensure that asingle article meets the requirement.6.4 AdhesionThe cadmium 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
41、end of thespecified test periods stated in Table 1 shall constitute failure,except 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
42、 required toguarantee satisfactory performance. Longer periods before the appearanceof 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 trea
43、tmentswithout requiring impractical testing periods.6.5.2 There are no requirements 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 di
44、fferent characteristic from those on partsthat are finished exclusively by racking. 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 ma
45、y be impractical for acceptance ofactual parts. In such cases the purchaser should 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 s
46、everal factors that influence the progress ofcorrosion, such as the formation of 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
47、where these materials may be used.Also, performance of different materials in the 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 rus
48、t shall apply.For example, for Type II, Class 5, the test shall be continueduntil 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 corrosio
49、n is met (8.5.2).6.6 Absence of Hydrogen EmbrittlementSteel springs andother high-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. Properly per-formed, s
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