ASTM B252-92(2020)
(Guide)Standard Guide for Preparation of Zinc Alloy Die Castings for Electroplating and Conversion Coatings
Standard Guide for Preparation of Zinc Alloy Die Castings for Electroplating and Conversion Coatings
SIGNIFICANCE AND USE
4.1 The performance and quality of electroplated or conversion-coated zinc alloy die casting depends upon the surface cleanliness and condition. Various metals are electroplated or conversion coatings are established on zinc alloys for decorative or engineering finish. The common electroplates applied are usually copper, nickel, and chromium for decorative and functional uses. The common conversion coatings applied are phosphates, chromates, and anodized coatings. Electroplated zinc die castings and conversion coatings on zinc die castings are used in many industries such as the marine, automotive, plumbing fixtures, and appliance industries.
SCOPE
1.1 This guide is intended as an aid in establishing and maintaining a procedure for preparing zinc alloy die castings for electroplating and conversion coatings. It is primarily intended for the preparation of Alloys UNS Z33521 (AG-40A) and UNS Z35530 (AC-41A) (Specification B86) for electroplating with copper, nickel, and chromium (Specification B456).
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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
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.
Designation: B252 − 92 (Reapproved 2020) Endorsed by American
Electroplaters’ Society
Endorsed by National
Association of Metal Finishers
Standard Guide for
Preparation of Zinc Alloy Die Castings for Electroplating
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and Conversion Coatings
This standard is issued under the fixed designation B252; 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.
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1. Scope 2.2 Military Standard:
MIL-S-13165C Shot Peening of Metal Parts
1.1 This guide is intended as an aid in establishing and
maintaining a procedure for preparing zinc alloy die castings
3. Summary of Practice
for electroplating and conversion coatings. It is primarily
3.1 The normal sequence of preparation steps is as follows:
intended for the preparation ofAlloys UNS Z33521 (AG-40A)
(1) smoothing of parting lines; (2) smoothing of rough or
and UNS Z35530 (AC-41A) (Specification B86) for electro-
defective surfaces, if necessary; (3) buffing, if necessary; (4)
plating with copper, nickel, and chromium (Specification
precleaning and rinsing; (5) alkaline electrocleaning and rins-
B456).
ing; (6) acid dipping and rinsing; and (7) copper striking.
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
4. Significance and Use
standard.
4.1 The performance and quality of electroplated or
1.3 This standard does not purport to address all of the
conversion-coated zinc alloy die casting depends upon the
safety concerns, if any, associated with its use. It is the
surface cleanliness and condition. Various metals are electro-
responsibility of the user of this standard to establish appro-
plated or conversion coatings are established on zinc alloys for
priate safety, health, and environmental practices and deter-
decorative or engineering finish. The common electroplates
mine the applicability of regulatory limitations prior to use.
applied are usually copper, nickel, and chromium for decora-
1.4 This international standard was developed in accor-
tive and functional uses. The common conversion coatings
dance with internationally recognized principles on standard-
applied are phosphates, chromates, and anodized coatings.
ization established in the Decision on Principles for the
Electroplated zinc die castings and conversion coatings on zinc
Development of International Standards, Guides and Recom-
die castings are used in many industries such as the marine,
mendations issued by the World Trade Organization Technical
automotive, plumbing fixtures, and appliance industries.
Barriers to Trade (TBT) Committee.
5. Composition and Characteristics of Zinc Alloy Die
2. Referenced Documents
Castings
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2.1 ASTM Standards:
5.1 The alloys used in the manufacture of zinc alloy die
B6 Specification for Zinc
castings are made with special high-grade zinc conforming to
B86 Specification for Zinc and Zinc-Aluminum (ZA) Alloy
Specification B6, alloyed with about 4 % of aluminum, 0.04 %
Foundry and Die Castings
of magnesium, and either 0.25 (max) or 1.0 % copper (Alloys
B456 Specification for Electrodeposited Coatings of Copper
UNS Z33521 and UNS Z35530). Impurities such as lead,
Plus Nickel Plus Chromium and Nickel Plus Chromium
cadmium, tin, and iron are held at or below the specified low
levels in Specification B86.
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This guide is under the jurisdiction of ASTM Committee B08 on Metallic and
5.2 Die castings made of Alloys UNS 233521 and UNS
Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 on Pre
235530 are usually dense and fine grained but do not always
Treatment.
have smooth surfaces. Defects sometimes encountered in the
Current edition approved Nov. 1, 2020. Published December 2020. Originally
approved in 1951. Last previous edition approved in 2014 as B252 – 92 (2014).
surfacelayersincludecracks,crevices(coldshut),skinblisters,
DOI: 10.1520/B0252-92R20.
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
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the ASTM website. Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
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B252 − 92 (2020)
and hemispherical pores. Burrs are us
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