ASTM B254-92(2004)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.
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 and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Endorsed by American
´1
Designation:B254–92(Reapproved 2004) 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 Department of Defense.
´ NOTE—Warning note updated in Section 7.3 in May 2004.
1. Scope of the stainless steel with which he is working before outlining
his electrodeposition procedure (see Appendix X1).
1.1 Various metals are electrodeposited on stainless steel for
3.2 Stainless steel surfaces are normally resistant to a wide
color matching, lubrication during cold heading, spring-coiling
variety of corrosive elements. This property is the result of a
and wire-drawing operations, reduction of scaling at high
thin transparent film of oxides present on the surface. Because
temperatures,improvementofwettability(asinfountainpens),
this film rapidly reforms after it has been stripped off or
improvement of heat and electrical conductance, prevention of
penetrated, it protects stainless steel against corrosion. An
galling, jewelry decoration, and prevention of superficial
adherent electrodeposit cannot be obtained over the oxide film
rusting.
normally present on stainless steel. However, once this film is
1.2 This practice is presented as an aid to electroplaters and
removed by surface activation and kept from reforming while
finishing engineers, confronted with problems inherent in the
the surface is covered with an electrodeposit, any of the
electrodeposition of metals on stainless steel. It is not a
commonly electroplated metals may be electrodeposited suc-
standardizedprocedurebutaguidetotheproductionofsmooth
cessfully on stainless steel.
adherent electrodeposits on stainless steel.
3.3 Where the finished product is to be subjected to severe
1.3 This standard does not purport to address all of the
exposure, the deposit produced by the proposed electroplating
safety concerns, if any, associated with its use. It is the
sequence should be tested under similar exposure conditions
responsibility of the user of this standard to establish appro-
before adoption, to determine whether the natural corrosion
priate safety and health practices and determine the applica-
resistance of the stainless steel has been impaired by the
bility of regulatory limitations prior to use.
presence of the electrodeposit.
2. Referenced Documents
4. Nature of Cleaning
2.1 ASTM Standards:
4.1 The preparation of stainless steel for electroplating
A380 Practice for Cleaning, Descaling, and Passivation of
involves three basic steps in the following order:
Stainless Steel Parts, Equipment, and Systems
4.1.1 Removalofscale.Ifscaleremovalisnecessary,oneof
3. Nature of Stainless Steel
the methods outlined in Appendix X2 may be used (Note 1).
See also Practice A380.
3.1 Because previous metal treatment may have a more
4.1.2 Removal of oil, grease, or other foreign material by
pronounced effect on the final finish when stainless steel is
cleaning, and
being electroplated, the metal finisher should become ac-
4.1.3 Activation immediately before electroplating.
quainted with the fabrication procedure, grade, and mill finish
4.2 Precleaning—Removal of fabricating lubricants and
finishing compounds from the stainless steel may have to be
This practice is under the jurisdiction of ASTM Committee B08 on Metallic
undertaken immediately following the fabrication or finishing
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 on
operation (Note 2).
Pre Treatment.
4.3 Electrocleaning—Anodic cleaning is generally pre-
Current edition approved April 1, 2004. Published May 2004. Originally
approved in 1951. Last previous edition approved in 1998 as B254–92 (1998). DOI:
ferred (Note 3).
10.1520/B0254-92R04E01.
4.4 Metal Lubricants—Metal lubricants such as copper,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
lead, or cadmium, applied to stainless steel wire for cold
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on heading, wire drawing, or spring forming are removed by
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
´1
B254–92 (2004)
immersioninasolutionof200mLofconcentrated,67mass %, Hydrochloric acid: 31 mass %; density 1.16 g/mL
nitricacid(density1.40g/mL)dilutedto1Lat50to60°C.See Nickel chloride: NiCl ·6H O
2 2
Practice A380. Copper sulfate: CuSO ·5H O
4 2
Warning—Sulfuric acid should be slowly added to the
NOTE 1—Oil, grease or other fabricating lubricants should be removed
approximate amount of water required with rapid mixing, and
by cleaning before heat treating.
then after cooling, diluted to exact volume.
NOTE 2—Spray cleaning with a nozzle pressure of 200 to 400 kPa (30
to 60 psi) in a power washer, using an alkaline or emulsion-type cleaner, 7.4 Cathodic Treatments:
is the generally preferred method, especially for the removal of heavy
drawing, buffing, or polishing compounds. Soak cleaning or vapor
7.4.1 Sulfuric acid 50 to 500 mL/L
degreasing may also be used. Extreme examples of such compounds are
Water to1L
drawing or stamping lubricants containing unsaturated oils, which if left
Temperature room
on the surface, form by air-oxidation tenacious films that are very difficult Time 1to5min
Current density 0.54 A/dm
to remove.
Anodes pure lead
NOTE 3—When brightness is important, alkalinity, current density, and
A
7.4.2 Hydrochloric acid 50 to 500 mL/L
temperature should be kept as low as the part will permit. This is an
Water to1L
essential requirement when cleaning work on racks bearing auxiliary lead
Temperature room
anodes or when high chromium alloys (such as UNS Types S44200 and
Time 1to5min
S44600) are being cleaned.
Current density 2.15 A/dm
Anodes electrolytic nickel strip or nickel
bar
5. Cleaning Solutions
A
See Patent No. 2,133,996.
5.1 The types of solution control, electrodes, heating coils,
7.4.3 After immersion in a solution containing 100 to 300 mL/L of hydrochlo-
ric acid diluted to 1 L at room temperature for 30 to 60 s, treat cathodically in:
and rinse tanks normally used for cleaning carbon steel are
Sulfuric acid 50 to 500 mL/L
satisfactory for stainless steel. Equipment previously used for
Water to1L
the cleaning or processing of carbon steel should not be used.
Temperature room
Current 0.54 to 2.7 A/dm
See Practice A380.
Anodes pure lead
6. Racking
7.5 Immersion Treatments:
6.1 The general principles of good racking as used in
7.5.1 Immerse in a solution of sulfuric acid containing 200
chromium electroplating processes apply. However, the high
to 500 mLof acid diluted to 1 Lat 65 to 80°C (with the higher
electrical resistance of stainless steel requires rack construction
temperature for the lower concentration) for at least 1 min after
methods that minimize potential contact problems and increase
gassing starts. If gassing does not start within 1 min after the
the number of contact points.
parts have been immersed, touch them with a carbon-steel bar
or rod. This activation treatment will produce a dark, adherent
NOTE 4—Because of the high electrical resistance of stainless steel,
smut that is removed in the electroplating bath. A cathodic
especiallyinfine-coiledwirearticlessuchaswatchbands,chains,jewelry,
etc., it is necessary to provide a larger number of contacts.As an example, current of at least 0.54 A/dm may be used to accelerate
a watch band 110 mm long made of 1.0-mm diameter wire has been found
activation. Lead anodes are suitable for this solution.
to require at least three contacts.
7.5.2 Immerse in the following solution:
Hydrochloric acid 1 mL
7. Activation
Sulfuric acid 10 mL
Water to1L
7.1 After the cleaning operation and before the electroplat-
Temperature room
ing operation, the parts must be completely activated, that is,
Time 26 s
the thin transparent film of oxides must be removed from the
NOTE 6—This practice has been used with success for chromium
surfacetobeelectroplated(Note5).Thisfilmwillreformifthe
electroplating on stainless steel automobile parts in a conveyorized
parts are allowed to dry or are exposed to oxygen-containing
process. It is not recommended before copper or nickel electroplating.
solutions. For this reason, the shortest interval practicable
should elapse between the time the parts are removed from the 7.6 Simultaneous Activation-Electroplating Treatments:
A
activating solution and covered by the electrodeposit, unless a
7.6.1 Nickel chloride 240 g
Hydrochloric acid 85 mL
simultaneous activation-electroplating procedure is used.
Iron should not exceed
7.5 g/ L
NOTE 5—The etching practice may be more severe for nondecorative
Water to1L
applications than for decorative applications.
Temperature room
Electrodes nickel
7.2 The following activating procedures have been used.
A
See U. S. Patent No. 2,285,548-9.
The procedure selected will depend upon the nature of the part
7.6.1.1 Anodic Treatment:
and preceding or subsequent processes (see 7.7). In the
following solution formulas, the concentrations are expressed
Current density 2.2 A/dm
Time 2 min
on a volume basis as follows:
7.6.1.2 Followed by Cathodic Treatment:
Liquids: as volume per litre of solution
Solids: as mass per litre of solution 2
Current density 2.2 A/dm
7.3 The commercial grade acids and salts used in the
Time 6 min
A
formulas include: 7.6.2 Nickel chloride 240 g
Hydrochloric acid 126 mL
Sulfuric acid: 93 mass %; density 1.83 g/mL
´1
B254–92 (2004)
8.1.3 If the simultaneous activation-plating procedure is
Water to1L
Electrodes nickel
employed and nickel plating follows, the intermediate rinse
B
Temperature room
need only be superficial and the length of transfer time is not
Current density (cathodic) 5.4 to 21.5 A/dm
so important.
Time 2to4min
A
See U. S. Patent No. 2,437,409.
B
9. Electroplating
Bath may require cooling or reduction in hydrochloric acid content if
temperature exceeds 30°C.
9.1 An adherent electrodeposit of commonly electroplated
7.6.3 Nickel chloride 30 to 300 g/L
metals (cadmium, copper, brass, chromium, gold, nickel, or
Hydrochloric acid 15 to 160 mL/L
Water to1L silver) may be electrodeposited directly on stainless steel
Electrodes nickel
provided the surface of the stainless steel is active.
Temperature room
Current density 0.55 to 10.75 A/dm
NOTE 8—Nickel may be electrodeposited at normal current densities
Time ⁄2 to5min
directly on properly activated stainless steel from standard nickel-
7.6.4 Hydrochloric acid undiluted commercial grade
electroplating solutions if the pH of the solution is between 2 and 4.ApH
(7.2)
of 2 is preferred.
Copper sulfate 0.4 g/L
Electrodes nickel NOTE 9—When a chromium-electroplating solution containing 400 g/L
Temperature room
of chromic acid is used for decorative chromium electroplating, better
Current density 4.5 to 6.6 A/dm
coverage and a wider bright range is obtained by operating at a current
Time 1to5min 2
density of 16.2 A/dm and 49°C.
NOTE 10—A bright nickel electroplate under chromium, preceded by
NOTE 7—Nickel anode materials containing greater than 0.01 % sulfur
one of the simultaneous activation-electroplating treatments, may often be
arenotrecommendedforuseinacidnickelstrikebathsoperatedatpH0.5,
used to advantage for better color matching and elimination of chromium
or lower, to avoid oxidation of sulfides by hydrochloric acid (see
buffing.
7.6.1-7.6.4, and 7.7).
9.2 Where practical, the parts should have the current
7.7 A combination of more than one type of treatment may
applied during entry into the electroplating solution.
be necessary to ensure a high degree of adhesion. For example,
the following has been used in the automotive industry for
10. Stripping
nickel plating on UNS Type S30200 stainless steel:
10.1 Nitric acid is the preferred stripping solution.
Sulfuric acid 650 mL
10.2 Decorative chromium electrodeposits have been
Water to1L
stripped in a solution of 500 mL of concentrated, 31 mass %
Potential (cathodic) 10 V
Electrodes lead
hydrochloric acid (density 1.16 g/mL) diluted to 1 L at 45 to
Temperature room
50°C for 1 min.
Time 2 min
NOTE 11—Overstripping will result in etching.
Followed by:
NOTE 12—Decorative chromium electrodeposits may also be stripped
Nickel chloride 240 g
anodically in any alkaline solution.
Hydrochloric acid 120 mL
Water to1L 10.3 Cadmium is stripped successfully without current by
Electrodes nickel
immersion in a solution of 120 g/L of ammonium nitrate.
Temperature room
Time 2 min
11. Post Electroplating Operations
Current density (cathodic) 16.2 A/dm
11.1 Post electroplating operations such as stress relieving,
This is followed by transfer without rinsing to a Watts (or
buffing or coloring, and forming or drawing may be applied to
higher chloride) nickel bath with a pH of 1.5 to 2.0.
stainless steel in the same manner as to any other basis metal,
as long as the natural differences in the characteristic of the
8. Rinsing
stainless steel are taken into consideration. The stainless steel
8.1 The parts should be transferred to the cold-water rinse
supplier should be consulted for guidance in regard to these
and to the plating solution as rapidly as practicable after the
characteristics.
activating procedure; otherwise the surface will passivate itself
12. Test Methods
and the electrodeposit will not be adherent.
12.1 The methods of testing for thickness, hardness, and
8.1.1 The rinse water should be kept slightly acid (approxi-
adhesion of electrodeposits applied with the usual basis metals
matelypHof2.5to3.5).Theacidcarryoverfromtheactivation
may be employed for similar tests on stainless steel.
operation will maintain this pH in many instances.
8.1.2 In conveyorized operations where trace contamination
NOTE 13—An exception to this is the determination of the thickness of
of plating solutions with chloride and sulfate from activating
chromium on stainless steel by the hydrochloric acid drop method.
Because gassing continues after the chromium coating has been pen-
solutions will produce an unsatisfactory electrodeposit, spray-
etrated, the accuracy of this method may be questionable for this
rinse operations subsequent to the activation treatment will
application.
remove thes
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.