1、_SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising theref
2、rom, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions.Copyright 2013 SAE InternationalAll rights reserved. No part of this publi
3、cation may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE.TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada)Tel: +1 724-776-4970 (out
4、side USA)Fax: 724-776-0790Email: CustomerServicesae.orgSAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedbackon this Technical Report, please visithttp:/www.sae.org/technical/standards/AMS2426EAEROSPACE MATERIAL SPECIFICATIONAMS2426 REV. EIssued 1966-09Reaffirmed 2007-04Revised
5、 2013-09Superseding AMS2426DCoating, CadmiumVacuum DepositionRATIONALEAMS2426E results from a Five Year Review and update of this specification.1. SCOPE1.1 PurposeThis specification covers the requirements for vacuum deposited cadmium.1.2 ApplicationThis process has been used typically to provide a
6、corrosion resistant coating for high strength ferrous parts operating at not higher than 450 F (232 C) and requiring freedom from hydrogen embrittlement, but usage is not limited to such applications. Deposits are “line-of-sight” and may not be applicable to some internal surfaces.1.3 Safety - Hazar
7、dous MaterialsWhile the materials, methods, applications, and processes described or referenced in this specification may involve the use of hazardous materials, this specification does not address the hazards that may be involved in such use. It is the sole responsibility of the user to ensure fami
8、liarity with the safe and proper use of any hazardous materials and to take necessary precautionary measures to ensure the health and safety of all personnel involved.1.4 WarningThis document includes cadmium as a coating material. The use of cadmium has been restricted and/or banned for use in many
9、 countries due to environmental and health concerns. The user should consult with local officials on applicable health and environmental regulations regarding its use.2. APPLICABLE DOCUMENTSThe issues of the following documents in effect on the date of the purchase order forms a part of this specifi
10、cation to the extent specified herein. The supplier may work to a subsequent revision of a document unless a specific document issue is specified. When the referenced document has been cancelled and no superseding document has been specified, the last published issue of that document shall apply.SAE
11、 INTERNATIONAL AMS2426E Page 2 of 72.1 SAE PublicationsAvailable from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org.AMS2750 PyrometryAS2390 Chemical Process Test Specimen Material2.2 ASTM Pub
12、licationsAvailable from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org.ASTM B 117 Operating Salt Spray (Fog) Testing ApparatusASTM B 487 Measurement of Metal and Oxide Coating Thicknesses by Microscopical Examination of a C
13、ross SectionASTM B 499 Measurement of Coating Thicknesses by the Magnetic Method; Nonmagnetic Coatings on Magnetic Basis MetalsASTM B 504 Measurement of Thickness of Metallic Coatings by the Coulometric MethodASTM B 568 Measurement of Coating Thickness by X-Ray SpectrometryASTM B 571 Adhesion of Met
14、allic Coatings3. TECHNICAL REQUIREMENTS3.1 Preparation3.1.1 Ferrous parts heat treated to a range including or exceeding a tensile strength of 240 ksi (1655 MPa) or hardness of 49 HRC shall not be exposed to processes that cause hydrogen embrittlement, such as pickling, cathodic cleaning, and etchin
15、g, or to corrosive environments.3.1.2 Prior to any processing which could cause hydrogen embrittlement, ferrous parts heat treated to a range including or exceeding a tensile strength of 180 ksi (1241 MPa) or hardness of 40 HRC that are machined, ground, cold formed or cold straightened after heat t
16、reatment shall be cleaned to remove surface contamination and thermally stress relieved. Furnaces used for stress relief shall be controlled per AMS2750; the minimum requirements shall be Class 5, with Type D Instrumentation. Temperatures to which parts are heated shall be such that stress relief is
17、 obtained while still maintaining hardness of parts within drawing limits. Unless otherwise specified, the following treatment temperatures and times shall be used:3.1.2.1 For parts, excluding nitrided parts, having a hardness of 55 HRC and above, and for carburized and induction hardened parts, str
18、ess relieve at 275 F r 25 (135 C r 14) for 5 to 10 hours.3.1.2.2 For parts having a hardness less than 55 HRC, and for nitrided parts, stress relieve at 375 F r 25 (191 C r 14) for a minimum of 4 hours. Higher temperatures shall be used only when specified or approved by the cognizant engineering or
19、ganization.3.1.2.3 For peened parts: If stress relief temperatures above 375 F (191 C) are elected, the stress relieve shall be performed prior to peening or the cognizant engineering organization shall be consulted and shall approve the stress relief temperature.SAE INTERNATIONAL AMS2426E Page 3 of
20、 73.1.3 Parts shall be within specified dimensional tolerances after coating.3.2 Procedure3.2.1 Cadmium shall be deposited directly onto the basis metal without a preliminary coating of other metal.3.2.2 Parts shall be coated by deposition of vaporized metallic cadmium within a suitable vacuum.3.2.2
21、.1 The equipment and processes employed shall be adequate to ensure coverage of all external surfaces, including roots of threads, recesses, and sharp corners.3.2.3 After coating, parts shall be conversion coated. Unless otherwise specified, a chromate conversion coating shall be used.3.3 Properties
22、The cadmium coating shall conform to the following requirements:3.3.1 Thickness shall be as specified on the drawing, determined in accordance with any of the following methods as applicable: ASTM B 487, ASTM B 499, ASTM B 504, ASTM B 568, direct micrometer measurement, or other method acceptable to
23、 the cognizant engineering organization.3.3.1.1 Coating thickness, when specified by AMS2426 and a suffix number, shall be as specified in Table 1 for the specified suffix number and type of part or surface.TABLE 1 - COATING THICKNESS AND SALT SPRAY CORROSION RESISTANCE REQUIREMENTSAMS 2426Thickness
24、DesignationSpecifiedExternalThreadsThicknessInchExternalThreadsThicknessMicrometersExternalThreadsSalt SprayResistanceHours, minNuts,Washers,andUnthreadedSurfaces ofParts ExternallyThreadedThicknessInchNuts,Washers,andUnthreadedSurfaces ofPartsExternallyThreadedThicknessMicrometersNuts,Washers,andUn
25、threadedSurfaces ofPartsExternallyThreadedSalt SprayResistanceHours, minPartsNotExternallyThreadedexceptNuts andWashersThicknessInchPartsNotExternallyThreadedexceptNuts andWashersThicknessMicrometersPartsNotExternallyThreadedexceptNuts andWashersSalt SprayResistanceHours, min2426 0.0001 2.5 100 0.00
26、02 5.1 150 0.0003 7.6 2000.0004 10 0.0005 12.7 0.0005 132426-1 0.0001 2.5 100 0.0002 5.1 150 0.0001 2.5 1000.0003 7.6 0.0004 10 0.0003 7.62426-2 0.0001 2.5 100 0.0002 5.1 150 0.0002 5.1 1500.0004 10 0.0004 10 0.0004 102426-3 0.0002 5.1 150 0.0003 7.6 200 0.0003 7.6 2000.0005 13 0.0005 13 0.0005 1324
27、26-4 0.0003 7.6 200 0.0004 10 225 0.0004 10 2250.0006 15 0.0006 15 0.0006 152426-5 0.0004 10 225 0.0005 13 250 0.0005 13 2500.0007 18 0.0007 18 0.0007 18Notes:For thickness designations AMS2426-X, where X is greater than 5, coating thickness in ten-thousandths of an inch shall be X to X+2 except on
28、external threads where coating thickness shall be X-1 to X+2; such parts shall withstand salt spray for not less than 250 hours.For thickness designations AMS2426-X, where X is greater than 5, coating thickness in micrometers shall be 2.5X to 2.5 (X+2) except on external threads where coating thickn
29、ess shall be 2.5 (X-1) to 2.5 (X+2); such parts shall withstand salt spray for not less than 250 hours.3.3.1.2 Where “cadmium flash” is specified, coating thickness shall be approximately 0.0001 inch (2.5 m).3.3.1.3 The coating shall be substantially uniform in thickness on significant surfaces exce
30、pt that slight build-up on exterior corners or edges will be permitted provided finished drawing dimensions are met.SAE INTERNATIONAL AMS2426E Page 4 of 73.3.1.4 All surfaces of the part, except those that cannot be touched by a sphere 0.75 inch (19 mm) in diameter, shall be coated to the specified
31、thickness. Unless otherwise specified, surfaces such as holes, recesses, threads and other areas where a controlled deposit cannot be obtained under normal coating conditions, may be under the specified limit provided they show visual coating coverage. Except as specified in Table 1 for externally t
32、hreaded sections, the resultant thickness shall be considered only when such surfaces of parts can be touched by a sphere 0.75 inch (19.0 mm) in diameter.3.3.2 Adhesion shall be determined using one of the following methods:3.3.2.1 Coating shall not show separation from the basis metal when tested i
33、n accordance with a method described in ASTM B 571.3.3.2.2 Coating shall not show separation from the basis metal when tested using a pressure sensitive tape with 2.5 pounds per inch (446 g/cm) minimum peel strength. The tape shall be applied to the coated surface, rolled into place using a rubber r
34、oller, and then rapidly removed by peeling the tape at a 90-degree angle to the coated surface.3.3.3 Corrosion ResistanceFerrous metal parts or representative test panels (4.3.3.2) processed with parts represented shall show no visual evidence of corrosion of the basis metal after being subjected fo
35、r a time not less than specified in Table 1 to continuous salt spray corrosion test conducted in accordance with ASTM B 117. When test specimens are used, coating thickness shall be 0.0002 to 0.0004 inch (5 to 10 m). Corrosion resistance shall not apply to non-ferrous parts, parts made of austenitic
36、 corrosion resistant steels, parts coated to a thickness less than 0.0002 inch (5 m), or to surfaces of parts such as holes, recesses, or threads that may have less than 0.0002 inch (5 m) coating thickness.3.3.3.13.4 QualityCadmium deposit, as received by purchaser, shall be smooth, continuous, adhe
37、rent to basis metal, uniform in appearance, and essentially free from pinholes, porosity, blisters, nodules, pits, and other imperfections detrimental to usage of the coating. Slight staining or discoloration is permissible.3.4.1 The cadmium deposit shall show no indication of contamination or impro
38、per operation of equipment used to produce the coating, such as powdery or darkened coatings.4. QUALITY ASSURANCE PROVISIONS4.1 Responsibility for InspectionThe processor shall supply all samples for processors tests and shall be responsible for the performance of all required tests. Parts, when req
39、uired for test, shall be supplied by purchaser. The cognizant engineering organization reserves the right to sample and to perform any confirmatory testing deemed necessary to ensure that processing conforms to the requirements of this specification.4.2 Classification of Tests4.2.1 Acceptance TestsT
40、hickness (3.3.1), adhesion (3.3.2), and quality (3.4) are acceptance tests and shall be performed on parts or specimens representing parts when permitted herein from each lot. See 4.3.3.4.2.2 Periodic TestsCorrosion-resistance (3.3.3) and tests of equipment and process controls to ensure that the de
41、posited metal will conform to the specified requirements are periodic tests and shall be performed at a frequency selected by the processor unless frequency of testing is specified by the cognizant engineering organization.SAE INTERNATIONAL AMS2426E Page 5 of 74.2.3 Preproduction TestsAll property v
42、erification tests (section 3.4) are preproduction tests and shall be performed prior to production and when the cognizant engineering organization requires confirmatory testing.4.3 Sampling for Testing4.3.1 Acceptance Tests Test samples shall be randomly selected from all parts in the lot. A lot sha
43、ll be all parts of the same part number, cleaned and pretreated as applicable at the same time in the same equipment, and coated in a single pumpdown, and presented for processors inspection at one time: Unless the cognizant engineering organization provides a sampling plan, the minimum number of sa
44、mples shall be as shown in Table 2.TABLE 2 - SAMPLING FOR ACCEPTANCE TESTINGNumber of Partsin Lot QualityThickness andAdhesionUp to 78 to 1516 to 4041 to 110111 to 300301 to 500501 to 700701 to 1200Over 1200all71015253550751253 or all4456781015* Whichever is less4.3.2 Periodic TestsSample quantities
45、 shall be at the discretion of the processor unless otherwise specified by the cognizant engineering organization.4.3.3 Sample ConfigurationNondestructive testing shall be performed wherever practical. Except as noted, actual parts shall be selected as samples for tests. When representative specimen
46、s are used for acceptance testing, values so obtained shall be correlated with those of parts since properties, such as thickness, may differ between parts and representative test specimens.4.3.3.1 Representative test specimens may be used in lieu of parts under any one of the following circumstance
47、s: The parts are of such configuration or size as to be not readily adaptable to specified tests, nondestructive testing is not practical on actual parts, or it is not economically acceptable to perform destructive tests on actual parts. Except as specified below, representative test specimens shall
48、 be made of the same generic class of alloy as the parts, established in accordance with AS2390, distributed within the lot, cleaned, and coated with the parts represented.4.3.3.2 Corrosion Testing When ferrous alloy parts are processed within the test period (quarter), representative test specimens
49、 shall be low carbon or low alloy steel 0.025 inch (0.63 mm) minimum thickness and not less than 4 x 6 inches (102 x 152 mm) or bars approximately 0.5 inch (13 mm) in diameter and four inches (102 mm) long having a surface roughness not to exceed 40 microinches (1 m) AA. Representative test specimens, made of the predominant generic class of alloy as the parts and coated within the test period m
