ASTM B254-92(2020)e1
(Practice)Standard Practice for Preparation of and Electroplating on Stainless Steel
Standard Practice for Preparation of and Electroplating on Stainless Steel
ABSTRACT
This practice covers the preparation and electroplating of metals on stainless steel. The preparation of stainless steel for electroplating involves three basic steps in the following order: removal of scale, removal of oil, grease, or other foreign material by cleaning, and activation immediately before electroplating. Activation shall be done by removing the thin transparent film of oxides from the surface to be electroplated. This film will reform if the parts are allowed to dry or are exposed to oxygen-containing solutions. For this reason, the shortest interval practicable should elapse between the time the parts are removed from the activating solution and covered by the electrodeposit, unless a simultaneous activation-electroplating procedure is used. The parts should be transferred to the cold-water rinse and to the plating solution as rapidly as practicable after the activating procedure; otherwise the surface will passivate itself and the electrodeposit will not be adherent. The rinse water should be kept slightly acid. After activation, an adherent electrodeposit of commonly electroplated metals like cadmium, copper, brass, chromium, gold, nickel, or silver may be electrodeposited directly on stainless steel provided the surface of the stainless steel. After stripping with nitric acid, post electroplating operations such as stress relieving, buffing or coloring, and forming or drawing may be applied to stainless steel in the same manner as to any other basis metal, as long as the natural differences in the characteristic of the stainless steel are taken into consideration. The methods of testing for thickness, hardness, and adhesion of electrodeposits applied with the usual basis metals may be employed for similar tests on stainless steel.
SCOPE
1.1 Various metals are electrodeposited on stainless steel for color matching, lubrication during cold heading, spring-coiling and wire-drawing operations, reduction of scaling at high temperatures, improvement of wettability (as in fountain pens), improvement of heat and electrical conductance, prevention of galling, jewelry decoration, and prevention of superficial rusting.
1.2 This practice is presented as an aid to electroplaters and finishing engineers, confronted with problems inherent in the electrodeposition of metals on stainless steel. It is not a standardized procedure but a guide to the production of smooth adherent electrodeposits on stainless steel.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: B254 − 92 (Reapproved 2020) Endorsed by American
Electroplaters’ Society
Endorsed by National Associa-
tion of Metal Finishers
Standard Practice for
Preparation of and Electroplating on Stainless Steel
This standard is issued under the fixed designation B254; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
ε NOTE—An editorial correction was made to X2.1.2 in December 2020.
1. Scope Stainless Steel Parts, Equipment, and Systems
1.1 Various metals are electrodeposited on stainless steel for
3. Nature of Stainless Steel
color matching, lubrication during cold heading, spring-coiling
and wire-drawing operations, reduction of scaling at high
3.1 Because previous metal treatment may have a more
temperatures,improvementofwettability(asinfountainpens),
pronounced effect on the final finish when stainless steel is
improvement of heat and electrical conductance, prevention of
being electroplated, the metal finisher should become ac-
galling, jewelry decoration, and prevention of superficial
quainted with the fabrication procedure, grade, and mill finish
rusting.
of the stainless steel with which he is working before outlining
1.2 This practice is presented as an aid to electroplaters and his electrodeposition procedure (see Appendix X1).
finishing engineers, confronted with problems inherent in the
3.2 Stainless steel surfaces are normally resistant to a wide
electrodeposition of metals on stainless steel. It is not a
variety of corrosive elements. This property is the result of a
standardizedprocedurebutaguidetotheproductionofsmooth
thin transparent film of oxides present on the surface. Because
adherent electrodeposits on stainless steel.
this film rapidly reforms after it has been stripped off or
1.3 This standard does not purport to address all of the
penetrated, it protects stainless steel against corrosion. An
safety concerns, if any, associated with its use. It is the
adherent electrodeposit cannot be obtained over the oxide film
responsibility of the user of this standard to establish appro-
normally present on stainless steel. However, once this film is
priate safety, health, and environmental practices and deter-
removed by surface activation and kept from reforming while
mine the applicability of regulatory limitations prior to use.
the surface is covered with an electrodeposit, any of the
1.4 This international standard was developed in accor-
commonly electroplated metals may be electrodeposited suc-
dance with internationally recognized principles on standard-
cessfully on stainless steel.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 3.3 Where the finished product is to be subjected to severe
mendations issued by the World Trade Organization Technical
exposure, the deposit produced by the proposed electroplating
Barriers to Trade (TBT) Committee. sequence should be tested under similar exposure conditions
before adoption, to determine whether the natural corrosion
2. Referenced Documents
resistance of the stainless steel has been impaired by the
presence of the electrodeposit.
2.1 ASTM Standards:
A380 Practice for Cleaning, Descaling, and Passivation of
4. Nature of Cleaning
4.1 The preparation of stainless steel for electroplating
This practice is under the jurisdiction of ASTM Committee B08 on Metallic
involves three basic steps in the following order:
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 on
Pre Treatment.
4.1.1 Removalofscale.Ifscaleremovalisnecessary,oneof
Current edition approved Nov. 1, 2020. Published December 2020. Originally
the methods outlined in Appendix X2 may be used (Note 1).
approvedin1951.Lastpreviouseditionapprovedin2014asB254 – 92(2014).DOI:
See also Practice A380.
10.1520/B0254-92R20E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4.1.2 Removal of oil, grease, or other foreign material by
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
cleaning, and
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 4.1.3 Activation immediately before electroplating.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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B254 − 92 (2020)
NOTE 5—The etching practice may be more severe for nondecorative
4.2 Precleaning—Removal of fabricating lubricants and
applications than for decorative applications.
finishing compounds from the stainless steel may have to be
undertaken immediately following the fabrication or finishing
7.2 The following activating procedures have been used.
operation (Note 2).
The procedure selected will depend upon the nature of the part
and preceding or subsequent processes (see 7.7). In the
4.3 Electrocleaning—Anodiccleaningisgenerallypreferred
following solution formulas, the concentrations are expressed
(Note 3).
on a volume basis as follows:
4.4 Metal Lubricants—Metal lubricants such as copper,
Liquids: as volume per litre of solution
lead, or cadmium, applied to stainless steel wire for cold
Solids: as mass per litre of solution
heading, wire drawing, or spring forming are removed by
7.3 The commercial grade acids and salts used in the
immersioninasolutionof200mLofconcentrated,67mass %,
formulas include:
nitric acid (density 1.40 g/mL) diluted to 1 L at 50 to 60 °C.
Sulfuric acid: 93 mass %; density 1.83 g/mL
See Practice A380.
Hydrochloric acid: 31 mass %; density 1.16 g/mL
NOTE 1—Oil, grease or other fabricating lubricants should be removed
Nickel chloride: NiCl ·6H O
2 2
by cleaning before heat treating.
Copper sulfate: CuSO ·5H O
NOTE 2—Spray cleaning with a nozzle pressure of 200 to 400 kPa (30 4 2
to 60 psi) in a power washer, using an alkaline or emulsion-type cleaner,
Warning—Sulfuric acid should be slowly added to the
is the generally preferred method, especially for the removal of heavy
approximate amount of water required with rapid mixing, and
drawing, buffing, or polishing compounds. Soak cleaning or vapor
then after cooling, diluted to exact volume.
degreasing may also be used. Extreme examples of such compounds are
drawing or stamping lubricants containing unsaturated oils, which if left
7.4 Cathodic Treatments:
on the surface, form by air-oxidation tenacious films that are very difficult
7.4.1 Sulfuric acid 50 to 500 mL/L
to remove.
Water to1L
NOTE 3—When brightness is important, alkalinity, current density, and
Temperature room
temperature should be kept as low as the part will permit. This is an
Time 1to5min
essential requirement when cleaning work on racks bearing auxiliary lead
Current density 0.54 A/dm
anodes or when high chromium alloys (such as UNS Types S44200 and
Anodes pure lead
A
S44600) are being cleaned.
7.4.2 Hydrochloric acid 50 to 500 mL/L
Water to1L
Temperature room
5. Cleaning Solutions
Time 1to5min
5.1 The types of solution control, electrodes, heating coils,
Current density 2.15 A/dm
Anodes electrolytic nickel strip or nickel
and rinse tanks normally used for cleaning carbon steel are
bar
satisfactory for stainless steel. Equipment previously used for
A
See Patent No. 2,133,996.
the cleaning or processing of carbon steel should not be used. 7.4.3 After immersion in a solution containing 100 to 300 mL/L of
hydrochloric acid diluted to 1 L at room temperature for 30 to 60 s, treat
See Practice A380.
cathodically in:
Sulfuric acid 50 to 500 mL/L
6. Racking
Water to1L
Temperature room
6.1 The general principles of good racking as used in
Current 0.54 to 2.7 A/dm
chromium electroplating processes apply. However, the high Anodes pure lead
electrical resistance of stainless steel requires rack construction
7.5 Immersion Treatments:
methods that minimize potential contact problems and increase
7.5.1 Immerse in a solution of sulfuric acid containing 200
the number of contact points.
to 500 mLof acid diluted to 1 Lat 65 to 80 °C (with the higher
NOTE 4—Because of the high electrical resistance of stainless steel,
temperature for the lower concentration) for at least 1 min after
especiallyinfine-coiledwirearticlessuchaswatchbands,chains,jewelry,
gassing starts. If gassing does not start within 1 min after the
etc., it is necessary to provide a larger number of contacts.As an example,
parts have been immersed, touch them with a carbon-steel bar
a watch band 110 mm long made of 1.0-mm diameter wire has been found
or rod. This activation treatment will produce a dark, adherent
to require at least three contacts.
smut that is removed in the electroplating bath. A cathodic
current of at least 0.54 A/dm may be used to accelerate
7. Activation
activation. Lead anodes are suitable for this solution.
7.1 After the cleaning operation and before the electroplat-
7.5.2 Immerse in the following solution:
ing operation, the parts must be completely activated, that is,
Hydrochloric acid 1 mL
the thin transparent film of oxides must be removed from the
Sulfuric acid 10 mL
surfacetobeelectroplated(Note5).Thisfilmwillreformifthe
Water to1L
parts are allowed to dry or are exposed to oxygen-containing
Temperature room
Time 26 s
solutions. For this reason, the shortest interval practicable
should elapse between the time the parts are removed from the
NOTE 6—This practice has been used with success for chromium
activating solution and covered by the electrodeposit, unless a
electroplating on stainless steel automobile parts in a conveyorized
simultaneous activation-electroplating procedure is used. process. It is not recommended before copper or nickel electroplating.
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B254 − 92 (2020)
7.6 Simultaneous Activation-Electroplating Treatments: activating procedure; otherwise the surface will passivate itself
A
and the electrodeposit will not be adherent.
7.6.1 Nickel chloride 240 g
Hydrochloric acid 85 mL
8.1.1 The rinse water should be kept slightly acid (approxi-
Iron should not exceed
matelypHof2.5to3.5).Theacidcarryoverfromtheactivation
7.5 g/L
operation will maintain this pH in many instances.
Water to1L
Temperature room
8.1.2 In conveyorized operations where trace contamination
Electrodes nickel
of plating solutions with chloride and sulfate from activating
A
See U. S. Patent No. 2,285,548-9.
solutions will produce an unsatisfactory electrodeposit, spray-
7.6.1.1 Anodic Treatment:
rinse operations subsequent to the activation treatment will
Current density 2.2 A/dm
remove these contaminants.
Time 2 min
8.1.3 If the simultaneous activation-plating procedure is
7.6.1.2 Followed by Cathodic Treatment:
employed and nickel plating follows, the intermediate rinse
need only be superficial and the length of transfer time is not
Current density 2.2 A/dm
Time 6 min
so important.
A
7.6.2 Nickel chloride 240 g
9. Electroplating
Hydrochloric acid 126 mL
Water to1L
9.1 An adherent electrodeposit of commonly electroplated
Electrodes nickel
B
Temperature room metals (cadmium, copper, brass, chromium, gold, nickel, or
Current density (cathodic) 5.4 to 21.5 A/dm
silver) may be electrodeposited directly on stainless steel
Time 2to4min
A provided the surface of the stainless steel is active.
See U. S. Patent No. 2,437,409.
B
Bath may require cooling or reduction in hydrochloric acid content if
NOTE 8—Nickel may be electrodeposited at normal current densities
temperature exceeds 30 °C.
directly on properly activated stainless steel from standard nickel-
7.6.3 Nickel chloride 30 to 300 g/L
electroplating solutions if the pH of the solution is between 2 and 4.ApH
Hydrochloric acid 15 to 160 mL/L
of 2 is preferred.
Water to1L
NOTE 9—When a chromium-electroplating solution containing 400 g/L
Electrodes nickel
of chromic acid is used for decorative chromium electroplating, better
Temperature room
coverage and a wider bright range is obtained by operating at a current
Current density 0.55 to 10.75 A/dm
density of 16.2 A/dm and 49 °C.
Time ⁄2 to5min
7.6.4 Hydrochloric acid undiluted commercial grade NOTE 10—A bright nickel electroplate under chromium, preceded by
(7.2)
one of the simultaneous activation-electroplating treatments, may often be
Copper sulfate 0.4 g/L
used to advantage for better color matching and elimination of chromium
Electrodes nickel
buffing.
Temperature room
Current density 4.5 to 6.6 A/dm
9.2 Where practical, the parts should have the current
Time 1to5min
applied during entry into the electroplating solution.
NOTE 7—Nickel anode materials containing greater than 0.01 % sulfur
10. Stripping
arenotrecommendedforuseinacidnickelstrikebathsoperatedatpH0.5,
or lower, to avoid oxidation of sulfides by hydrochloric acid (see
10.1 Nitric acid is the preferred stripping solution.
7.6.1-7.6.4, and 7.7).
10.2 Decorative chromium electrodeposits have been
7.7 A combination of more than one type of treatment may
stripped in a solution of 500 mL of concentrated, 31 mass %
be necessary to ensure a high degree of adhesion. For example,
hydrochloric acid (density 1.16 g/mL) diluted to 1 L at 45 to
the following has been used in the automotive industry for
50 °C for 1 min.
nickel plating on UNS Type S30200 stainless steel:
NOTE 11—Overstripping will result in etching.
Sulfuric acid 650 mL
NOTE 12—Decorative chromium electrodeposits may also be stripped
Water to1L
anodically in any alkaline solution.
Potential (cathodic) 10 V
Electrodes lead
10.3 Cadmium is stripped successfully without current by
Temperature room
immersion in a solution of 120 g/L of ammonium nitrate.
Time 2 min
Followed by:
11. Post Electroplating Operations
Nickel chloride 240 g
11.1 Post electroplating operations such as stress relieving,
Hydrochloric acid 120 mL
buffing or coloring, and forming or drawing may be applied to
Water to1L
Electrodes nickel
stainless steel in the same manner as to any other basis metal,
Temperature room
as long as the natural differences in the characteristic of the
Time 2 min
2 stainless steel are taken into consideration. The stainless steel
Current density (cathodic) 16.2 A/dm
supplier should be consulted for guidance in regard to these
This is followed by transfer without rinsing to a Watts (or
characteristics.
higher chloride) nickel bath with a pH of 1.5 to 2.0.
12. Test Methods
8. Rinsing
12.1 The methods of testing for thick
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