1、Designation: B842 99 (Reapproved 2011)Standard Specification forElectrodeposited Coatings of Zinc Iron Alloy Deposits1This standard is issued under the fixed designation B842; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r 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 electrode-posited zinc iron alloy coatings on metals.1.2 The value
3、s stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 The following precautionary caveat pertains to the testmethod portion only, Section 8, of this specification: Thisstandard does not purport to address all of the safety concerns,if any,
4、 associated with its use. It is the responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to use.2. Referenced Documents2.1 ASTM Standards:2B117 Practice for Operating Salt Spray (Fog) Apparatus
5、B183 Practice for Preparation of Low-Carbon Steel forElectroplatingB242 Guide for Preparation of High-Carbon Steel for Elec-troplatingB320 Practice for Preparation of Iron Castings for Electro-platingB322 Guide for Cleaning Metals Prior to ElectroplatingB374 Terminology Relating to ElectroplatingB48
6、7 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination of CrossSectionB499 Test Method for Measurement of Coating Thick-nesses by the Magnetic Method: Nonmagnetic Coatings onMagnetic Basis MetalsB504 Test Method for Measurement of Thickness of Me-tallic Coatin
7、gs by the Coulometric MethodB568 Test Method for Measurement of Coating Thicknessby X-Ray SpectrometryB571 Practice for Qualitative Adhesion Testing of MetallicCoatingsB602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsB697 Guide for Selection of Sampling Plans for Inspectionof
8、 Electrodeposited Metallic and Inorganic CoatingsB762 Test Method of Variables Sampling of Metallic andInorganic CoatingsB849 Specification for Pre-Treatments of Iron or Steel forReducing Risk of Hydrogen EmbrittlementB850 Guide for Post-Coating Treatments of Steel for Re-ducing the Risk of Hydrogen
9、 EmbrittlementD3951 Practice for Commercial Packaging3. Terminology3.1 DefinitionsMany terms used in this specification aredefined in Terminology B374.3.2 Definitions of Terms Specific to This Standard:3.2.1 significant surface, nthat portion of a coated arti-cles surface where the coating is requir
10、ed to meet all therequirements of the coating specification for that article.3.2.1.1 DiscussionSignificant surfaces are usually thosethat are essential to the serviceability or function of the article,or that can be a source of corrosion products or tarnish filmsthat interfere with the function or d
11、esirable appearance of thearticle. Significant surfaces are those surfaces that are identi-fied by the purchaser by, for example, indicating them on anengineering drawing of the product or marking a sample itemof the product.4. Classification4.1 There is one class of zinc iron alloy that is defined
12、asfollows:4.1.1 Class 1Deposits having approximately 99 mass %zinc, balance iron.4.2 There are two coating types that are defined as follows:4.2.1 Type AZinc iron with black chromate conversioncoating, and4.2.2 Type BZinc iron with iridescent yellow chromateconversion coating.1This specification is
13、under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct responsibility of SubcommitteeB08.08.04 onSoft Metals.Current edition approved April 1, 2011. Published April 2011. Originallyapproved in 1993. Last previous edition approved in 2005 as B842 99(2005). DO
14、I:10.1520/B0842-99R11.2For 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 standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr
15、 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.3 There are three coating grades according to thicknessthat are defined as follows:Minimum Thickness, m New ASTM Grade Old ASTM Grade66112 12 218 18 35. Ordering Information5.1 In order to make the application of this spec
16、ificationcomplete, the purchaser needs to supply the following infor-mation to the seller in the purchase order and drawings:5.1.1 Title, ASTM designation number, and date of issue ofthis specification,5.1.2 Deposit by classification including class (see 4.1),type (see 4.2), and grade (see 4.3),5.1.
17、3 Composition and metallurgical condition of the sub-strate to be coated,5.1.4 Location of significant surfaces (see 3.2),5.1.5 Heat treatment for stress relief, whether it has beenperformed by purchaser or is required (see 6.7),5.1.6 Heat treatment after electroplating, if required (see6.8),5.1.7 A
18、ny requirement for submission of sample coatedarticles,5.1.8 Whether or not location of rack marks is to be defined(see 6.3.1),5.1.9 Any requirement for special test specimens (see 8.1),5.1.10 Acceptance inspection procedure to be used (seeSection 8),5.1.11 Any requirement for certification (see Sec
19、tion 10),and5.1.12 Any other items needing agreement. For the purposesof this specification, prior agreement on the nature of the finishis required as items plated in bulk may differ slightly inappearance from those that are rack plated.6. Coating Requirements6.1 SubstrateThe metal to be plated shal
20、l be free of flawsand defects that will be detrimental to the zinc alloy coating. Itshall be subjected to such cleaning, pickling, and electroplatingprocedures as are necessary to yield deposits with the desiredquality.NOTE 1Proper preparatory procedures and thorough cleaning areessential to ensure
21、satisfactory adhesion and corrosion resistance perfor-mance of the coating. Materials used for cleaning should not damage thebasis metal. It is recommended that the following practices for cleaning beused, where appropriate: Practices B183 and B320, and Guides B242 andB322.6.1.1 The electroplating s
22、hall be applied after all basis metalheat treatments have been completed.6.2 Nature of CoatingThe coating shall consist of a zinciron alloy that is approximately 99 mass % zinc and the balanceiron.6.3 Appearance:6.3.1 The coating on all readily visible surfaces shall havean acceptable and characteri
23、stic appearance as agreed upon bythe purchaser and seller. The coating shall be uniform insofaras the basis metal will permit. When the article is to be platedon a rack, contact marks may be unavoidable. Location of suchmarks(s) shall be indicated on the article or its drawing.6.3.2 Defects and vari
24、ations in appearance that arise fromsurface conditions of the substrate (scratches, pores, roll marks,inclusions, and the like) and that persist in the coating despitethe observance of good metal finishing practices shall not because for rejection. The coating shall be adherent, free fromblisters, p
25、its, or discontinuities, and shall be free of cracks inthe as-plated state. Flaking shall be cause for rejection in eitherthe as-plated state or after subsequent operations.NOTE 2These coatings are commonly used in automotive applica-tions where subsequent forming, bending, and crimping operations a
26、recommonly performed. These operations will necessarily detract from theperformance of the coatings. While some cracking of coatings will beunavoidable, flaking of the coating after these subsequent operations shallbe cause for rejection.NOTE 3Coatings generally perform better in service when the su
27、b-strate over which they are applied is smooth and free of torn metal,inclusions, pores, and other defects. The specifications covering theunfinished product should provide limits for these defects.Ametal finishercan often remove defects through special treatments, such as grinding,polishing, abrasi
28、ve blasting, chemical etches, and electropolishing. How-ever, these are not normal in the treatment steps preceding the applicationof the coating. When they are desired, they are the subject of specialagreement between the purchaser and the seller.6.4 ThicknessThe thickness of the coating everywhere
29、 onthe significant surfaces shall conform to the requirements asspecified in 4.2 and defined in 3.2.1.NOTE 4The coating requirement of this specification is a minimum.Variation in the thickness from point to point on an article and from articleto article in a production lot is inherent in electropla
30、ting. Therefore, if allof the articles in a production lot are to meet the thickness requirement, theaverage coating thickness for the production lot as a whole will be greaterthan the specified minimum.6.5 AdhesionThe coating shall withstand normal handlingand storage conditions without chipping, f
31、laking, or othercoating damage and shall conform to the minimum require-ments set forth in Section 8.6.6 Corrosion ResistanceThe corrosion resistance of thecoating may be evaluated using the method in Appendix X1.6.7 Pretreatment of Iron and Steel to Reduce the Risk ofHydrogen Embrittlement:6.7.1 Pa
32、rts that are made of steels with ultimate tensilestrengths of 1000 MPa (hardness of 31 HRC or greater) thathave been machined, ground, cold formed, or cold straightenedsubsequent to heat treatment shall require stress relief heattreatment when specified by the purchaser, the tensile strengthto be su
33、pplied by the purchaser. Specification B849 may beconsulted for a list of pretreatments that are widely used.6.8 Coating Treatments of Iron and Steel to Reduce the Riskof Hydrogen Embrittlement:6.8.1 Parts that are made of steels with ultimate tensilestrengths of 1000 MPa (hardness of 31 HRC or grea
34、ter) as wellas surface hardened parts, may require post-coating hydrogenembrittlement relief baking when specified by the purchaser,the tensile strength to be supplied by the purchaser. GuideB850 may be consulted for a list of post-treatments that arewidely used.B842 99 (2011)27. Sampling7.1 The sam
35、pling plan used for the inspection of a quantityof the coated articles shall be as agreed upon between thepurchaser and the seller.NOTE 5Usually, when a collection of coated articles, the inspectionlot (see 7.2), is examined for compliance with the requirements placed onthe articles, a relatively sm
36、all number of the articles, the sample, isselected at random and is inspected. The inspection lot is then classified ascomplying or not complying with the requirements based on the results ofthe inspection of the sample. The size of the sample and the criteria forcompliance are determined by the app
37、lication of statistics. This procedureis known as sampling inspection. Three standards, Test Method B602,Guide B697, and Test Method B762, contain sampling plans that aredesigned for the sampling inspection of coatings. Test Method B602contains four sampling plans, three for use with tests that are
38、nondestruc-tive and one for destructive tests. The buyer and seller may agree on theplan or plans to be used. If they do not, Test Method B602 identifies theplan to be used. Guide B697 provides a large number of plans and alsogives guidance in the selection of a plan. When Guide B697 is specified,th
39、e buyer and seller need to agree on the plan to be used. Test MethodB762 can be used only for coating requirements that have a numericallimit, such as a coating thickness. The test must yield a numerical valueand certain statistical requirements must be met. Test Method B762contains several plans an
40、d also gives instructions for calculating plans tomeet special needs. The buyer and the seller may agree on the plan orplans to be used. If they do not, Test Method B762 identifies the plan tobe used.NOTE 6When both destructive and nondestructive tests exist for themeasurement of a characteristic, t
41、he purchaser needs to state which is tobe used so that the proper sampling plan is selected.Atest may destroy thecoating but in a noncritical area, or, although it may destroy the coating,a tested part can be reclaimed by stripping and recoating. The purchaserneeds to state whether the test is to be
42、 considered destructive ornondestructive.7.2 An inspection lot shall be defined as a collection ofcoated articles that are of the same kind, that have beenproduced to the same specification, that have been coated by asingle supplier at one time or at approximately the same timeunder essentially iden
43、tical conditions, and that are submittedfor acceptance or rejection as a group.7.3 If special test specimens are used to represent the coatedarticles in a test, the number used shall be that required in 8.1.1.8. Test Methods8.1 Special Test Specimens:8.1.1 The permission or the requirement to use sp
44、ecial testspecimens, the number to be used, the material from whichthey are to be made, and the shape and size of the specimens,shall be stated by the purchaser.NOTE 7Test specimens often are used to represent the coated articlesin a test if the articles are of a size, shape, or material that is not
45、 suitablefor the test, or if it is preferred not to submit articles to a destructive testbecause, for example, the articles are expensive or few in number. Thespecimen should duplicate the characteristics of the article that influencethe property being tested.8.1.2 Special test specimens used to rep
46、resent articles in anadhesion, porosity, corrosion resistance, or appearance testshall be made of the same material, in the same metallurgicalcondition, and have the same surface condition as the articlesthey represent, and be placed in the production lot of and beprocessed along with the articles t
47、hey represent.8.1.3 Special test specimens used to represent articles in acoating thickness test may be made of a material that is suitablefor the test method even if the represented article is not of thesame material. For example, a low-carbon steel specimen mayrepresent a brass article when the ma
48、gnetic thickness test isused (see Test Method B499). The thickness specimen need notbe carried through the complete process with the representedarticle. If not, introduce it into the process at the point wherethe coating is applied and carry it through all steps that have abearing on the coating thi
49、ckness. In rack plating, rack thespecimen in the same way with the same distance from andorientation with the anodes and other items in the process asthe article it represents.NOTE 8When special test specimens are used to represent coatedarticles in a thickness test, the specimens will not necessarily have thesame thickness and thickness distribution as the articles unless thespecimens and the articles are of the same general size and shape.Therefore, before finished articles can be accepted on the basis of athickness test performed on special test specimens, th
