1、Designation: B841 99 (Reapproved 2010)B841 18Standard Specification forElectrodeposited Coatings of Zinc Nickel Alloy Deposits1This standard is issued under the fixed designation B841; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision
2、, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers the requirements for electrodeposited zinc nickel alloy coatings on metals.1.2
3、 The values stated in SI units are to be regarded as the standard.1.3 The following precautionary statement pertains to the test method portion only, Section 8, of this specification:This standarddoes not purport to address all of the safety concerns, if any, associated with its use. It is the respo
4、nsibility of the user of thisstandard to establish appropriate safety safety, health, and healthenvironmental practices and determine the applicability ofregulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on stan
5、dardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2B117 Practice for Operating Salt Spray (Fog) Ap
6、paratusB183 Practice for Preparation of Low-Carbon Steel for ElectroplatingB242 Guide for Preparation of High-Carbon Steel for ElectroplatingB320 Practice for Preparation of Iron Castings for ElectroplatingB322 Guide for Cleaning Metals Prior to ElectroplatingB374 Terminology Relating to Electroplat
7、ingB487 Test Method for Measurement of Metal and Oxide Coating Thickness by Microscopical Examination of Cross SectionB499 Test Method for Measurement of CoatingThicknesses by the Magnetic Method: Nonmagnetic Coatings on Magnetic BasisMetalsB504 Test Method for Measurement of Thickness of Metallic C
8、oatings by the Coulometric MethodB507 Practice for Design of Articles to Be Electroplated on RacksB568 Test Method for Measurement of Coating Thickness by X-Ray SpectrometryB571 Practice for Qualitative Adhesion Testing of Metallic CoatingsB602 Test Method for Attribute Sampling of Metallic and Inor
9、ganic CoatingsB697 Guide for Selection of Sampling Plans for Inspection of Electrodeposited Metallic and Inorganic CoatingsB762 Test Method of Variables Sampling of Metallic and Inorganic CoatingsB849 Specification for Pre-Treatments of Iron or Steel for Reducing Risk of Hydrogen EmbrittlementB850 G
10、uide for Post-Coating Treatments of Steel for Reducing the Risk of Hydrogen EmbrittlementD3951 Practice for Commercial Packaging3. Terminology3.1 DefinitionsMany items used in this specification are defined in Terminology B374.3.2 Definitions of Terms Specific to This Standard:1 This specification i
11、s under the jurisdiction ofASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.06 on SoftMetals.Current edition approved Jan. 1, 2010July 1, 2018. Published February 2010July 2018. Originally approved in 1993. Last previous edition approved in 1
12、20042018 asB841 99(2004).(2018). DOI: 10.1520/B0841-99R09.10.1520/B0841-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the
13、 ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users con
14、sult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.1 significant surface, nthat p
15、ortion of a coated articles surface where the coating is required to meet all the requirementsof the coating specification for that article. Significant surfaces are usually those that are essential to the serviceability or functionof the article, or that can be a source of corrosion products or tar
16、nish films that interfere with the function or desirable appearanceof the article.3.2.2 DiscussionSignificant surfaces are those surfaces that are identified by the purchaser by, for example, indicating themon an engineering drawing of the product or marking a sample item of the product.4. Classific
17、ation4.1 There is one classare two classes of zinc nickel coating defined as follows:4.1.1 Class 1Deposits having a minimum of 5 and maximum 12 mass % nickel, the balance being zinc.4.1.2 Class 2Deposits having a minimum of 12 and maximum 16 mass % nickel, the balance being zinc.4.2 There are five c
18、hromate conversion coating or passivation types that are defined as follows:Conversion DesignationType Description Hexavalent Chromium Non-Hexavalent ChromiumType A Colorless (Blue Bright) Conversion A ANType B Yellow Iridescent Conversion B BNType C Bronze Conversion C CNType D Black Chromate Conve
19、rsion D DNType E Any of the above plus organic topcoat E4.2.1 Type AWith colorless (blue bright) conversion coatings,NOTE 1Whereas colored chromate conversion coatings are usually meant to include various shades of yellow to bronze when used with nonalloyedzinc, yellow and bronze chromate conversion
20、 coatings are considered distinctly different in appearance and performance when applied to alloyed zinccoatings and are formulated specifically to produce the desired coating and are formulated specifically to produce the desired coating.4.2.2 Type BWith yellow iridescent conversion coatings,4.2.3
21、Type CWith bronze conversion coatings,4.2.4 Type DWith black chromate conversion coatings, and4.2.5 Type EAny of the above plus organic topcoat.NOTE 1Whereas colored chromate conversion coatings are usually meant to include various shades of yellow to bronze when used with nonalloyedzinc, yellow and
22、 bronze chromate conversion coatings are considered distinctly different in appearance and performance when applied to alloyed zinccoatings and are formulated specifically to produce the desired coating and are formulated specifically to produce the desired coating.4.3 There are three grades accordi
23、ng to thickness and are defined as follows:Minimum Thickness, m New ASTM Grade Old ASTM Grade5 5 18 8 210 10 35. Ordering Information5.1 In order to make the application of this specification complete, the purchaser needs to supply the following information tothe seller in the purchase order and dra
24、wings:5.1.1 Title, ASTM designation number, and date of issue of this standard specification,5.1.2 Deposit by classification including Class, Type, and Grade (see 4.1, 4.2, 4.3),5.1.3 Composition and metallurgical condition of the substrate to be coated,5.1.4 Location of significant surfaces (see 3.
25、2.1),5.1.5 Heat treatment for stress relief, whether it has been performed by purchaser or is required (see 6.7),5.1.6 Heat treatment after electroplating, if required (see 6.8),5.1.7 Whether or not location of rack marks is to be defined (see 6.3.1),5.1.8 Any requirement for special test specimens
26、(see 8.1.1),5.1.9 Acceptance inspection procedure to be used (see Section 8), and5.1.10 Any requirement for certification (see Section 10).5.1.11 Any other items needing agreement. For the purposes of this specification, prior agreement on the nature of the finishis required as items plated in bulk
27、may differ in appearance from those that are rack plated.6. Coating Requirements6.1 SubstrateThe metal to be plated shall be free of flaws and defects that will be detrimental to the zinc alloy coating. It shallbe subjected to such cleaning, pickling, and electroplating procedures as are necessary t
28、o yield deposits with the desired quality.NOTE 2Proper preparatory procedures and thorough cleaning are essential to ensure satisfactory adhesion and corrosion resistance performance ofthe coating. Materials used for cleaning should not damage the basis metal, for example by causing defects such as
29、pits, intergranular attack or stresscorrosion cracking. It is recommended that the following practices for cleaning, where appropriate, be used: Practices B183 and B320, and Guides B242and B322.B841 1826.1.1 The electroplating shall be applied after all basis metal heat treatments have been complete
30、d.6.2 Nature of Coating:6.2.1 The coating zinc-nickel alloy plate shall consist of a zinc nickel alloy that has a minimum of 5 and maximum 12 masspercent nickel, the balance being position conforming to the requirements called out in section 4.1.6.2.2 The coating shall be produced from an aqueous el
31、ectroplating system that may be either an alkaline or acid formulationas specified by the purchaser.6.2.3 The coating shall have such supplementary conversion coatings as defined in 4.2 and specified in the purchase order.6.3 Appearance:6.3.1 The coating on all ready visible surfaces shall have an a
32、cceptable and characteristic appearance as agreed upon by thepurchaser and seller. The coating shall be uniform insofar as the basis metal will permit. When the article is to be plated on a rack,contact marks may be unavoidable. Location of such marks(s) shall be indicated on the article or its draw
33、ing.6.3.2 Defects and variations in appearance that arise from surface conditions of the substrate (scratches, pores, roll marks,inclusions, and the like) and that persist in the coating despite the observance of good metal finishing practices shall not be causefor rejection. The coating shall be ad
34、herent, free from blisters, pits, discontinuities, or discontinuities, combinations thereof, andshall be free of cracks in the as plated state. Flaking shall be cause for rejection in either the as plated state or after subsequentoperations.NOTE 3These coatings are commonly used in automotive applic
35、ations where subsequent forming, bending, and crimping operations are commonlyperformed. These operations will necessarily detract from the performance of the coatings. While some cracking of coatings will be unavoidable, flakingof the coating after these subsequent operations shall be cause for rej
36、ection.NOTE 4Coatings 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. The specifications covering the unfinished product should provide limits for these defects. A metal finisher can often remov
37、e defectsthrough special treatments, such as grinding, polishing, abrasive blasting, chemical etches, and electropolishing. However, these are not normal in thetreatment steps preceding the application of the coating. When they are desired, they are the subject of special agreement between the purch
38、aser and theseller.6.4 Thickness:6.4.1 The thickness of the coating everywhere on the significant surfaces as defined in 3.2.1 and shall conform to therequirements of the specified grade as defined in 4.3.NOTE 5The thickness of electrodeposited coatings varies from point to point on the surfaces of
39、a product (see Practice B507). The thickness is lessin interior corners and in holes. Such surfaces are often exempt from thickness requirements. If the full thickness is required in those locations, theelectroplater will have to use special techniques that will probably raise the cost of the proces
40、s.NOTE 6The coating requirement of this specification is a minimum. Variation in the thickness from point to point on an article and from article toarticle in a production lot is inherent in electroplating. Therefore, if all of the articles in a production lot are to meet the thickness requirement,
41、the averagecoating thickness for the production lot as a whole will be greater than the specified minimum.6.5 AdhesionThe coating shall withstand normal handling and storage conditions without chipping, flaking, or other coatingdamage and shall conform to the minimum requirements set forth in Sectio
42、n 8.6.6 CorrosionCorrosion resistance is applicable to the significant surfaces only. The corrosion resistance of the coating maybe evaluated using the methodcriteria in Appendix X1.6.7 Pretreatment of Iron and Steel for Reducing the Risk of Hydrogen Embrittlement:6.7.1 Parts that are made of steels
43、 with ultimate tensile strengths of 1000 MPa (hardness of 31 HRC or greater) that have beenmachined, ground, cold formed, or cold straightened subsequent to heat treatment shall require stress relief heat treatment whenspecified by the purchaser, the tensile strength to be supplied by the purchaser.
44、 Specification B849 may be consulted for a list ofpre-treatments that are widely used.6.8 Post-Coating Treatments of Iron and Steel for Reducing the Risk of Hydrogen Embrittlement:6.8.1 Parts that are made of steels with ultimate tensile strengths of 1000 MPa (hardness of 31 HRC or greater), as well
45、 assurface hardened parts, may require post-coating hydrogen embrittlement relief baking when specified by the purchaser, the tensilestrength to be supplied by the purchaser. Specification B850 may be consulted for a list of post-treatments that are widely used.7. Sampling7.1 The sampling plan used
46、for the inspection of a quantity of the coated articles shall be as agreed upon between the purchaserand the seller.NOTE 7Usually, when a collection of coated articles, the inspection lot (see 7.2), is examined for compliance with the requirements placed on thearticles, a relatively small number of
47、the articles, the sample, is selected at random and is inspected. The inspection lot is then classified as complyingor not complying with the requirements based on the results of the inspection of the sample. The size of the sample and the criteria of compliance aredetermined by the application of s
48、tatistics. The procedure is known as sampling inspection. Three standards, Test Method B602, Guide B697, and TestMethod B762 contain sampling plans that are designed for the sampling inspection of coatings. Test Method B602 contains four sampling plans, threefor use with tests that are nondestructiv
49、e and one when they are destructive. The buyer and seller may agree on the plan or plans to be used. If they donot, Test Method B602 identifies the plan to be used. Guide B697 provides a large number of plans and also gives guidance in the selection of a plan.When Guide B697 is specified, the buyer and seller need to agree on the plan to be used. Test Method B762 can be used only for coating requirementsB841 183that have a numerical limit, such as a coating thickness. The test must yield a numerical value and certain statistical requirements must b
