Home>ASTM Standards>ASTM B242-99(R2020) pdf free download

ASTM B242-99(R2020) pdf free download

ASTM B242-99(R2020) pdf free download.Standard Guide for Preparation of High-Carbon Steel for Electroplating
1. Scope
1.1 This guide 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 guide, 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. N OTE 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 guide does not apply to the electroplating of alloy steel. For methods ofchromium electroplating directly on steel, see Guide B177. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 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 appro- priate safety, health, and environmental practices and deter- mine the applicability of regulatory limitations prior to use. For a specific hazards statement, see 3.1. 1.5 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4.2 Hydrogen Embrittlement—Difficulties resulting from hydrogen embrittlement increase with increasing hardness, whether produced by heat treatment or cold work. Difficulties, during or after electroplating of hardened high-carbon steel parts, may in some cases be minimized without material change in hardness by baking before final pretreatment. For a listing of such hydrogen embrittlement relief bake cycles, consult Guide B850. 4.3 Surface Oxidation—In order that subsequent treatments be facilitated, every reasonable precaution should be taken throughout the processing to limit oxidation or scale formation. In particular cases pre-electroplating with copper to a mini- mum thickness of 13 µm may assist in maintaining a preferred surface through the heat treatment. A nonoxidizing atmosphere should be maintained in the furnace. This copper shall be removed prior to the regular electroplating cycle. Care should be used in oil-quenching parts heat treated in a salt bath, to prevent the charring effect that can be caused by salt-bath drag-out. Proper lead-bath quenching results in only slight oxidation. 4.4 Steel Quality—The quality of the steel should be char- acteristic of the requirement of the product and the electroplat- ing operation. The steel should be free of injurious surface defects, and of at least average cleanliness.
5. Preparation of Steel, General
5.1 Preparatory Treatments—A wide variety of surface conditions are encountered in high-carbon steel articles to be electroplated. The surface may require the removal of one or more of the following contaminants: grease, oil or drawing compounds, burned-in oil scale, light to heavy treatment scale, permeable oxide films, emery and fine steel particles resulting from the grinding operation. The removal ofsuch contaminants is accomplished by one or more of the following pretreatment procedures where applicable: 5.1.1 Substantial removal of oil, grease, and caked-on dirt by precleaning before the part enters the electroplating cycle (applicable in all cases). 5.1.2 Mechanical treatment ofthe surface by tumbling, sand or grit blasting, vapor blasting, or grinding (optional). 5.1.3 Final and complete anodic cleaning in an electrolytic alkali cleaner. 5.1.4 Acid treatment in HCl to remove the last trace ofoxide and scale. This should be avoided for spring temper and case-hardened parts. This treatment also removes residual traces of lead that may be present following proper lead-bath quenching. 5.1.5 Smut removal by cyanide dipping or by anodic treat- ment in cyanide or alkali. 5.1.6 Final preparation for electroplating may be accom- plished by an anodic etching treatment in H 2 SO 4 (used when- ever possible in the interest of high yield and adhesion).

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