ASTM B242-99
(Guide)Standard Guide for Preparation of High-Carbon Steel For Electroplating
Standard Guide for Preparation of High-Carbon Steel For Electroplating
SCOPE
1.1 This practice is intended as an aid in establishing and maintaining a preparatory cycle for electroplating on high-carbon steel (Note 1) producing a minimum of hydrogen embrittlement and maximum adhesion of the electrodeposited metal. For the purpose of this practice, steels containing 0.35% of carbon or more, and case-hardened low-carbon steel, are defined as high-carbon steels. There is no generally recognized definite carbon content dividing high- from low-carbon steels for electroplating purposes. Note 1-Electroplating of plain high-carbon steel introduced problems not found in similar operations on low-carbon steel. During the cleaning and electroplating cycle, high-carbon steel differs from low-carbon steel in regard to its greater tendency to become embrittled and the greater difficulty in obtaining maximum adhesion of the electrodeposit. The preparation of low-carbon steel for electroplating is covered in Practice B183.
1.2 This practice does not apply to the electroplating of alloy steel. For methods of chromium electroplating directly on steel see Practice B177.
1.3 This standard does not purport to address all of the safety problems 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. For a specific hazards statement, see 3.1.
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Endorsed by American
Designation: B 242 – 99 Electroplaters’ Society
Endorsed by National
Association of Metal Finishers
Standard Guide for
Preparation of High-Carbon Steel for Electroplating
This standard is issued under the fixed designation B 242; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Reagents
1.1 This guide is intended as an aid in establishing and 3.1 Purity of Reagents—All acids and chemicals used in
maintaining a preparatory cycle for electroplating on high- this practice are technical grade. Acid solutions are based upon
carbon steel (Note 1) producing a minimum of hydrogen the following assay materials:
embrittlement and maximum adhesion of the electrodeposited Hydrochloric acid (HCl) 31 mass %, density 1.16 g/mL
metal. For the purpose of this guide, steels containing 0.35 % Nitric acid (HNO ) 67 mass %, density 1.40 g/mL
of carbon or more, and case-hardened low-carbon steel, are Sulfuric acid (H SO ) 93 mass %, density 1.83 g/mL
2 4
defined as high-carbon steels. There is no generally recognized Caution—Dilute sulfuric acid by slowly adding it to the
definite carbon content dividing highfrom low-carbon steels for approximate amount of water required with rapid mixing. After
electroplating purposes. cooling, bring the mixture to exact volume.
3.2 Purity of Water—Use ordinary industrial or potable
NOTE 1—Electroplating of plain high-carbon steel introduced problems
water for preparing solutions and rinsing.
not found in similar operations on low-carbon steel. During the cleaning
and electroplating cycle, high-carbon steel differs from low-carbon steel in
4. Nature of Steel
regard to its greater tendency to become embrittled and the greater
difficulty in obtaining maximum adhesion of the electrodeposit. The 4.1 Hardness—High hardness is a major cause of cracking
preparation of low-carbon steel for electroplating is covered in Practice
of the steel during or after electroplating. The recommended
B 183.
maximum hardness range for classes of products depends on
1.2 This guide does not apply to the electroplating of alloy their geometry and service requirements (Note 2). Parts hard-
steel. For methods of chromium electroplating directly on steel ened by heat treatment should be inspected before electroplat-
see Guide B 177. ing for the presence of cracks by a suitable method, such as
1.3 This standard does not purport to address all of the magnetic or fluorescent powder inspection.
safety problems associated with its use. It is the responsibility
NOTE 2—Some examples of parts and Rockwell hardness ranges are as
of the user of this standard to establish appropriate safety and
follows:
health practices and determine the applicability of regulatory
Rockwell Hard-
limitations prior to use. For a specific hazards statement, see
ness Range
Springs C45 to C48
3.1.
Spring washers C45 to C53
Small instrument parts C52 to C55
2. Referenced Documents
Parts to be chromium electroplated C57 to C62
for engineering use
2.1 ASTM Standards:
B 177 Practice for Chromium Electroplating on Steel for 4.2 Hydrogen Embrittlement—Difficulties resulting from
Engineering Use
hydrogen embrittlement increase with increasing hardness,
B 183 Practice for Preparation of Low-Carbon Steel for whether produced by heat treatment or cold work. Difficulties,
Electroplating
during or after electroplating of hardened high-carbon steel
B 849 Specification for Pre-Treatments of Iron or Steel for parts, may in some cases be minimized without material
Reducing the Risk of Hydrogen Embrittlement
change in hardness by baking before final pretreatment. For a
B 850 Specification for Post-Coating Treatments of Iron or listing of such hydrogen embrittlement relief bake cycles,
Steel for Reducing the Risk of Hydrogen Embrittlement
consult Specification B 850.
4.3 Surface Oxidation—In order that subsequent treatments
be facilitated, every reasonable precaution should be taken
This guide is under the jurisdiction of ASTM Committee B-8 on Metallic and
throughout the processing to limit oxidation or scale formation.
Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 on
In particular cases pre-electroplating with copper to a mini-
Substrate Preparation.
Current edition approved Oct. 10, 1999. Published December 1999. Originally mum thickness of 13 μm may assist in maintaining a preferred
published as B 242 – 49 T. Last previous edition B 242 – 54 (1990).
surface through the heat treatment. A nonoxidizing atmosphere
Annual Book of ASTM Standards, Vol 02.05.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B 242
should be maintained in the furnace. This copper shall be selected process steps combined into pretreatment cycles of
removed prior to the regular electroplating cycle. Care should greater or less complexity according to the condition and
be used in oil-quenching parts heat treated in a salt bath, to properties of the material. The minimum number of steps
prevent the charring effect that can be caused by salt-bath necessary to accomplish the electroplating satisfactorily is
drag-out. Proper lead-bath quenching results in only slight recommended.
oxidation.
4.4 Steel Quality—The quality of the steel should be char-
6. Preliminary Pretreatment Procedures
acteristic of the requirement of the product and the electroplat-
6.1 Application—Degreasing and mechanical surface treat-
ing operation. The steel should be free of injurious surface
ment are necessary only where the high-carbon steel parts are
defects, and of at least average cleanliness.
contaminated to such an extent that otherwise the burden
imposed on the pretreatment cycle would impair its efficiency,
5. Preparation of Steel, General
increase its complexity, and tend to prevent the attainment of
5.1 Preparatory Treatments—A wide variety of surface
the required quality of the deposit. The overall cost of the
conditions are encountered in high-carbon steel articles to be
electroplating process is usually reduced by using the prelimi-
electroplated. The surface may require the removal of one or
nary treatments where applicable. Oil, grease, dirt, drawing
more of the following contaminants: grease, oil or drawing
compounds, burnt-in oil, heavy scale, and emery and steel
compounds, burned-in oil scale, light to heavy treatment scale,
particles are typical of the gross contaminants encountered.
permeable oxide films, emery and fine steel particles resulting
6.2 Precleaning—Solvent-degreasing with clean solvent,
from the grinding operation. The removal of such contaminants
spray-washing, or emulsion-cleaning, followed by electrolytic
is accomplished by one or more of the following pretreatment
or soak-alkali cleaners are recommended. The former types are
procedures where applicable:
preferred to reduce the burden on the alkali treatments.
5.1.1 Substantial removal of oil, grease, and caked-on dirt
Soak-alkali cleaning is usual for parts that are to be barrel
by precleaning before the part enters the electroplating cycle
electroplated. Electrolytic cleaning should always be anodic
(applicable in all cases).
where the control of embrittlement is a problem.
5.1.2 Mechanical treatment of the surface by tumbling, sand
6.3 Stress Relief Treatment—It is recommended that hard-
or grit blasting, vapor blasting, or grinding (optional).
ened high-carbon steel parts receive a stress-relief bake before
5.1.3 Final and complete anodic cleaning in an electrolytic
the parts are mechanically pretreated or enter the final pretreat-
alkali cleaner.
ment cycle, or both. For a listing of typical stress-relief bakes,
5.1.4 Acid treatment in HCl to remove the last trace of oxide
consult Specification B 849.
and scale. This should be avoided for spring temper and
6.4 Mechanical Treatment—The purpose of mechanical
case-hardened parts. This treatment also removes residual
treatment is to reduce subsequent acid pickling to a minimum.
traces of lead that may be present following proper lead-bath
Where mechanical treatment has been accomplished with
quenching.
precision, it is sometimes possible to eliminate acid pickling
5.1.5 Smut removal by cyanide dipping or by anodic treat-
entirely, thus improving the control of hydrogen embrittlement.
ment in cyanide or alkali.
When required, mechanical treatment of small parts is best
5.1.6 Final preparation for electroplating may be accom-
effected by tumbling. All scaled and nearly all oil-quenched
plished by an anodic etching treatment in H SO (used when-
2 4
materials require mechanical cleaning such as by tumbling
ever possible in the interest of high yield and adhesion).
with or without abrasive, or by sand, grit, or vapor blasting.
5.1.7 Conditioning of the surface to be electroplated may be
These operations should be carried out so as to avoid severe
accomplished, where necessary for the electroplating process,
roughening of the surface with accompanying notch effect.
by a short dip or rinse in a solution equivalent to the
One resorts to grinding in certain cases where the surface
electroplating solution without its metallic content.
smoothness or dimensions of the parts are of critical impor-
5.2 Rinsing—Inadequate rinsing after each solution treat-
tance, for example, in chromium electroplating for engineering
ment step is the recognized cause of a large portion of
use.
electroplating difficulties. Not enough rinsing is characteristic
of most pretreatment cycles.
7. Final Pretreatment Procedures
5.3 Pretreatment Time—All processing steps involving hy-
7.1 Application—Final cleaning, oxide removal, and anodic
drogen generation must be designed to operate for a minimum
length of time, to avoid hydrogen embrittlement of the high- acid treatment are fundamental steps required for preparing
high-carbon steel for electroplating. These pretreatment steps
carbon steel.
5.4 Control—All pretreatment steps should be carried out are designed to assist in the control of hydrogen embrittlement
and in securing the maximum adhesion of the electroplated
with solutions that are maintained in good working condition
coating.
by control of composition and contaminants, and used under
7.2 Electrolytic Anodic Cleaning:
conditions of time, temperature and current density specified to
meet the requirement of the work being processed. 7.2.1 All work, except work to be barrel electroplated,
5.5 Pretreatment Cycle Design—Depending upon the re- should preferably be cleaned in an electrolytic anodic alkaline
quirements for the particular high-carbon steel parts to be cleaner. Anodic cleaning is recommended to avoid hydrogen
electroplated, a minimum cycle should be selected from the embrittlement that is likely to result from cathodi
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