AMS2404 Plating, Electroless Nickel Rev. G
AMS2404 Plating, Electroless Nickel Rev. G
AMS2404 Plating, Electroless Nickel Rev. G
AMS2404 REV. G
AEROSPACE MATERIAL
SPECIFICATION Issued 1957-09
Revised 2013-12
RATIONALE
AMS2404G results from a Five Year Review and includes updated requirements for stress relief of steels prior to plating.
NOTICE
ORDERING INFORMATION: The following information shall be provided to the plating processor by the purchaser.
NOTE: This specification has been used to supersede AMS-C-26074 which employs Grade designations to convey
thickness requirements. See 8.13 for a complete cross reference from AMS-C-26074 callouts to the technically
identical provisions within this specification in order to comply with the following purchase order requirements.
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1. SCOPE
1.1 Purpose
This specification covers the requirements for electroless nickel deposited on various materials.
1.2 Application
This deposit has been used typically to provide a uniform build-up on intricate shapes, to improve wear and/or corrosion
resistance, or to improve solderability on or for selected materials, but usage is not limited to such applications. The
deposit has been used in service up to 1000 °F (540 °C) although wear and/or corrosion resistance may degrade as
service temperature increases.
1.2.1 Application of electroless nickel plating to steel parts having a hardness of 46 HRC (ultimate tensile strength of
220 ksi (1517 MPa) or higher shall not be performed unless authorized by the design documentation or specific
approval has been received from the cognizant engineering organization.
1.3 Classification
Class 1: Except for hydrogen embrittlement relief, no post plating thermal treatment.
Class 2: Thermal treatment at 450 °F (232 °C) or above to harden the deposit.
Class 3: Thermal treatment at 375 °F (191 °C) to improve adhesion for nonheat-treatable aluminum alloys and beryllium
alloys.
While 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 which may be involved in such use. It is the
responsibility of the user to ensure familiarity 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.
2. APPLICABLE DOCUMENTS
The issue of the following documents in effect on the date of the purchase order forms a part of this specification 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.
Available 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.
Available 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 487 Measurement of Metal and Oxide Coating Thicknesses by Microscopical Examination of a Cross Section
ASTM B 499 Measurement of Coating Thicknesses by the Magnetic Method: Nonmagnetic Coatings on Magnetic Basis
Metals
ASTM B 567 Method for Measurement of Coating Thickness by the Beta Backscatter Method
ASTM B 636 Measurement of Internal Stress of Plated Metallic Coatings with the Spiral Contractometer
ASTM B 748 Measurement of Thickness of Metallic Coatings by Measurement of Cross Section with a Scanning
Electron Microscope
ASTM B 764 Simultaneous Thickness and Electrochemical Potential Determination of Individual Layers in Multilayer
Nickel Deposit (STEP Test)
3. TECHNICAL REQUIREMENTS
3.1 Preparation
All steel parts having a hardness of 40 HRC and above and that are machined, ground, cold formed or cold straightened
after heat treatment shall be cleaned to remove surface contamination and thermally stress relieved before plating.
(Residual tensile stresses have been found to be damaging during electroplating.) 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 obtained while still maintaining hardness of parts within drawing
limits. Unless otherwise specified, the following treatment temperatures and times shall be used:
3.1.1.1 For parts, excluding nitrided parts, having a hardness of 55 HRC and above, including carburized and induction
hardened parts, stress relieve at 275 °F ± 25 (135 °C ± 14) for 5 to 10 hours.
3.1.1.2 For parts having a hardness less than 55 HRC, stress relieve at 375 °F ± 25 (191 °C ± 14) for a minimum of 4 Distributed by Thomson Reuters (Scientific) LLC, www.t
hours. Nitrided parts fall into this category. Higher temperatures shall be used only when specified or approved
by the cognizant engineering organization.
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.
3.1.2 Cleaning
The plating shall be applied over a surface free from water breaks. The cleaning procedure shall not produce pitting or
intergranular attack of the basis metal and shall preserve dimensional requirements.
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3.2 Procedure
3.2.1 Plating shall be performed by chemical deposition of a nickel-phosphorus coating onto a properly prepared
surface.
3.2.2 Plated parts shall be removed from the plating solution, thoroughly rinsed, and dried.
Treatment of steel parts shall be in accordance with AMS2759/9. Other metals and alloys do not require hydrogen
embrittlement relief baking
When Class 2, 3, or 4 is specified, parts, after plating, rinsing, and drying, shall be thermally treated.
3.3.2.1 When Class 2 is specified, parts shall be heated to a selected temperature within the range of 450 to 800 °F
(232 to 427 °C) and held for sufficient time to increase hardness of the deposit. See 3.4.4 and 8.6. Hydrogen
embrittlement relief (3.3.1) may be omitted if Class 2 hardening is started within 4 hours after plating.
3.3.2.2 When Class 3 is specified, parts shall be heated to 375 °F ± 15 (191 °C ± 8) for 1 to 1.5 hours.
3.3.2.3 When Class 4 is specified, parts shall be heated to 250 °F ± 10 (121 °C ± 6) for 1 to 1.5 hours.
3.4.1 Unless otherwise specified, minimum thickness of the nickel coating shall be 0.0010 inch (0.025 mm) for
aluminum based alloys, 0.0005 inch (0.013 mm) for copper, nickel, cobalt, titanium and beryllium alloys, and
0.0015 inch (0.038 mm) for iron-based alloys. Thickness shall be determined in accordance with ASTM B 487,
ASTM B 499, ASTM B 567, ASTM B 568, ASTM B 748, ASTM B 764, or by other method acceptable to the
cognizant engineering organization. See 8.13 for thickness requirements specified by AMS-C-26074 Grade
designations.
3.4.2 Adhesion shall meet the requirements of ASTM B 571 bend test 180 degree with 4T mandrel or, when acceptable
to the cognizant engineering organization, 3.4.2.1. may be used to demonstrate acceptable adhesion.
3.4.2.1 Plating on steel alloys shall comply with all criteria of 3.5 after being heated in air, preferably in a circulating-air
furnace, at 700 °F ± 15 (371 °C ± 8) for 23 hours ± 1 followed by heating at 1000 °F ± 15 (538 °C ± 8) for
60 minutes ± 5.
Carbon and low-alloy steel parts or test panels (4.3.1.3) having minimum plating thickness of 0.001 inch (25 µm), shall,
after plating and embrittlement-relieving, show no visual evidence of corrosion of the basis metal after being subjected for
not less than 48 hours to continuous salt spray corrosion test conducted in accordance with ASTM B 117. See 4.3.1.3.
3.4.3.1 When AMS-C-26074 Grade A is specified, aluminum alloy parts or test panels having minimum plating
thickness of 0.0010 inch (25 µm), shall, after plating and thermal treatment, show no visual evidence of
corrosion of the basis metal after being subjected for not less than 100 hours to continuous salt spray corrosion
test conducted in accordance with ASTM B 117.
3.4.3.2 When AMS-C-26074 Grade B is specified, corrosion resistance testing does not apply.
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3.4.3.3 When AMS-C-26074 Grade C is specified, carbon and low alloy steel parts or test panels having minimum
plating thickness of 0.0015 inch (38 µm), shall, after plating and embrittlement-relieving, show no visual
evidence of corrosion of the basis metal after being subjected for not less than 100 hours to continuous salt
spray corrosion test conducted in accordance with ASTM B 117.
3.4.4 Hardness
Class 2 plating shall be not lower than 800 HK100 (773HV100), or equivalent, determined in accordance with
ASTM E 384. See 3.3.2.1.
The plating process shall not cause hydrogen embrittlement in steel parts, after baking, determined in accordance with
4.3.1.4.
The cognizant engineering organization may specify a compressive stress value for Class 1 plating up to 10 ksi (69 MPa),
determined in accordance with ASTM B 636, or other test method acceptable to the cognizant engineering organization.
3.4.7 Composition
The cognizant engineering organization may specify a phosphorus content range of the deposit. When specified, the
composition of the deposit shall be determined by a method acceptable to the cognizant engineering organization.
3.5 Quality
The processor shall supply all samples for processor’s test and shall be responsible for the performance of all required
tests. Parts, if required for tests, 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 plating conforms to specified
requirements.
Thickness (3.4.1), adhesion (3.4.2), and quality (3.5) are acceptance tests and shall be performed on parts, or samples
When corrosion resistance testing is required by 3.4.3, corrosion resistance (3.4.3) is a periodic test and shall be
performed at least monthly unless frequency of testing is specified by the cognizant engineering organization. Internal
stress, if specified (3.4.6), and composition, if specified (3.4.7) 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. Tests of
cleaning and plating solutions are periodic tests and shall be performed at a frequency established by the processor unless
frequency of testing is specified by the cognizant engineering organization. See 8.4 and 4.4.3. Testing for hydrogen
embrittlement (3.4.5) is a periodic test and shall be performed in accordance with 4.3.1.4 at least once in each month that
parts 36 HRC and over are plated. Testing for hardness (3.4.4) is a periodic test and shall be performed at least once in
each month.
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4.2.3 Preproduction Tests
All technical requirements are preproduction tests and shall be performed prior to or on the initial shipment of plated parts
to a purchaser, when a change in material and/or processing requires approval by the cognizant engineering organization
(4.4.2), and when the cognizant engineering organization requires confirmatory testing.
4.3.1.1 Nondestructive testing shall be performed wherever practical. Except as noted below, actual parts shall be
selected as samples for tests.
4.3.1.2 Except as specified below, acceptance test specimens shall be made of the same generic class of alloy as the
parts, established in accordance with AS2390, distributed within the lot, cleaned, plated, and post treated with
the parts. Separate test specimens shall be used when plated parts are of such configuration or size as to be
not readily adaptable to specified tests, when nondestructive testing is not practical on actual parts, or it is not
economically acceptable to perform destructive tests on actual parts.
In any month (or other specified test period) that ferrous alloy parts are plated, test panels shall be low carbon or low alloy
steel 0.025 inch (0.6 mm) minimum thickness and not less than 4 inches (102 mm) wide by 6 inches (152 mm) long.
Aluminum alloy test panels, (same panel size as for steel) made of either 2024-T3 or the same generic class of alloy as
the parts being plated, shall be used in any month (or other specified test period) when aluminum alloy parts are plated.
When an internal stress requirement is imposed by the cognizant engineering organization, test specimens shall be plated
to a thickness not less than 0.0006 inch (15 µm) and shall conform to ASTM B 636 or other test method acceptable to the
cognizant engineering organization.
4.3.2.1 Acceptance tests shall be in accordance with Table 1; a lot shall be all parts of the same part number, plated to
the same range of plate thickness in the same solutions, in each 8 hours of continuous production, and
presented for processor’s inspection at one time.
Number of
Parts in Thickness and
Lot Quality Adhesion
Up to 7 All All or 3*
8 to 15 7 4
16 to 40 10 4
41 to 110 15 5
111 to 300 25 6
301 to 500 35 7
501 to 700 50 8
701 to 1200 75 10
Over 1200 125 15
*Whichever is less
Sample size shall be four for corrosion resistance (when required by 3.4.3). For hydrogen embrittlement, sample size shall
be as specified in ASTM F 519 unless otherwise specified by the cognizant engineering organization. Sample quantity for
other tests and frequency of testing shall be at the discretion of the processor unless otherwise specified by the cognizant
engineering organization or herein.
4.4 Approval
4.4.1 The process and control factors, a preproduction part, or both, whichever is specified, shall be approved by the
cognizant engineering organization before production parts are supplied.
4.4.3 Control factors shall include, but not be limited to, the following:
4.5 Reports
4.6.1 If any acceptance test fails to meet specified test requirements, the parts in that lot may be stripped, pretreated,
plated, post treated as defined herein, and retested. Alternatively, all parts in the lot may be inspected for the
nonconforming attribute, and the nonconforming parts may be stripped, pretreated, plated, post treated as defined
herein, and retested.
4.6.1.1 When stripping is performed, the method shall be acceptable to the cognizant engineering organization and
shall not roughen, pit, or embrittle the basis metal or adversely affect part dimensions. When parts have been
stripped and replated, the purchaser shall be informed.
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4.6.2 If any periodic test fails to meet specified test requirements, the process is nonconforming. No additional parts
shall be plated until the process is corrected and new specimens are plated and tested. Results of all tests shall be
recorded and, when requested, reported. Purchaser shall be notified of all parts plated since the last acceptable
periodic test.
5.1 Plated parts shall be handled and packaged to ensure that required physical characteristics and properties of the
plating are preserved.
5.2 Packages of plated parts shall be prepared for shipment in accordance with commercial practice and in compliance
with applicable rules and regulations pertaining to the handling, packaging, and transportation of the plated parts to
ensure carrier acceptance and safe delivery.
6. ACKNOWLEDGMENT
A processor shall mention AMS2404G in all quotations and when acknowledging purchase orders.
7. REJECTIONS
Parts on which plating does not conform to this specification, or to modifications authorized by the cognizant engineering
organization, will be subject to rejection.
8. NOTES
8.1 A change bar (|) located in the left margin is for the convenience of the user in locating areas where technical
revisions, not editorial changes, have been made to the previous issue of this document. An (R) symbol to the left of
8.2 Part manufacturing operations, such as heat treatment, forming, joining, and media finishing, can affect the
condition of the substrate for plating, or, if performed after plating, could adversely affect the plate. The sequencing
of these operations should be specified by the cognizant engineering organization and is not controlled by this
specification.
8.3 The parts manufacturer should ensure that the surfaces of the metal parts supplied to the plater are free from
blemishes, pits, tool marks, and other irregularities that will affect the quality of the finished parts. Defects and
variations in appearance that arise from surface conditions of the substrate, such as porosity, scratches or
inclusions, that persist in the finish plate despite observance of accepted industry practices are not cause for
rejection.
8.4 ARP4992, Periodic Test Plan for Process Solutions, is recommended to satisfy the requirements for the control of
processing solutions.
8.5 An acid dip may be used for surface activation or neutralization of residual alkaline cleaner. However, the immersion
time, as measured in seconds, should be minimized to preclude pitting.
8.6 The following thermal treatments have been used to achieve Class 2 hardness requirements. The supplier is Distributed by Thomson Reuters (Scientific) LLC, www.t
cautioned to avoid a thermal treatment that could soften or otherwise degrade the substrate.
8.8 Phosphorus content of the plate may range from 1 to 13% by weight. Ductility is generally less for low phosphorus
(2 to 8%) deposits compared with high phosphorus (8 to 13%) deposits. Class 1 deposits that are low in phosphorus
generally have less corrosion resistance than Class 1 high-phosphorus deposits whereas Class 2 deposits that are
high in phosphorus may provide less salt fog corrosion protection to steel than Class 2 low-phosphorus coatings.
8.9 Terms used in AMS are clarified in ARP1917. ASTM B 374 “Terminology Relating to Electroplating” should be
utilized as a reference and referee document when areas of design definition or technical interpretation arise.
8.9.1 Plating is intended to be deposited in an uninterrupted process except as may be required by the operator for
making thickness measurements. After the plate has dried, resumption of plating can result in detectable visual
discontinuities or weak interlaminar adhesion that may not be readily apparent. Such resumption of plating is
known as ‘double plating’ and localized addition of plate is known as ‘spotting-in.’
8.10 Dimensions and properties in inch/pound units and the Fahrenheit temperatures are primary; dimensions and
properties in SI units and the Celsius temperatures are shown as the approximate equivalents of the primary units
and are presented only for information.
8.11 AMS2404G has been written to provide equivalent technical requirements and to allow users to supersede AMS-C-
26074 and MIL-C-26074.
8.12 Peening
A reduction in the fatigue life of plated parts may occur, attributed to the plating adhesion, physical characteristics,
mechanical properties and state of stress. Parts designed for unlimited fatigue life under dynamic loads are generally
8.13 AMS-C-26074 and its predecessor specifications encourage the use of Grade designations to specify thickness.
Grade A means that 0.0010 inch (25 µm) minimum plate thickness is applied. This applies normally to, but is not limited to,
aluminum-based alloys.
Grade B means that 0.0005 inch (13 µm) minimum plate thickness is applied. This applies normally to, but is not limited to,
copper, nickel, cobalt, titanium and beryllium alloys.
Grade C means that 0.0015 inch (38 µm) minimum plate thickness is applied. This applies normally to, but is not limited to,
iron-based alloys.
8.13.1 AMS-C-26074 and its predecessor specifications permit the use of hydrogen embrittlement testing on parts which
is different from the normal notched tensile bar testing in 4.3.1.4. When the cognizant engineering organization
8.13.2 Other paragraphs herein that form a bridge from AMS-C-26074 and predecessor specifications can be found in
3.4.3.
8.14 This process is not recommended for materials subject to overtempering or high temperature embrittlement when
exposed to the post-plating heat treatment applicable to class 2, 3 or 4 as specified. See 3.3.2. Electroless nickel
plating on steel parts having an ultimate tensile strength of 220 ksi (1517 MPa) or above (46 HRC and above) is not
recommended.