ASTM B177/B177M-11(2021) PDF

ABSTRACT This guide provides information on the deposition of engineering chromium by electroplating. This is sometimes called "functional" or "hard" chromium and is usually applied directly to the basis metal and is usually thicker than decorative deposits. This guide is not intended as a standardized procedure, but as a guide for obtaining smooth, adherent coatings of a desired thickness while retaining the required physical and mechanical properties of the base metals. Engineering chromium may be plated directly to the surface of a commonly used engineering metals such as aluminum, nickel alloys, cast iron, steels, copper, copper alloys, and titanium. Substrate requirements including smoothness, fatigue, high-strength steel stress relief, and oxidation are specified. The procedure and requirements for the following are detailed: (1) racking, including rack and anode designs, (2) cleaning, (3) deoxidizing and etching such as anodic etching in chromic acid solution, in plating solution, and in sulfuric acid solution, and slight etching by acid immersion, (4) chromium electroplating process, (5) treatment of chromium coatings such as baking to avoid hydrogen embrittlement, and mechanical finishing by grinding, grinding and honing, or lapping, (6) repair of chromium electrodeposits on steel substrates, and (7) test methods such as thickness determination, hardness test, and adhesion test. SCOPE 1.1 This guide provides information about the deposition of chromium on steel for engineering uses. This is sometimes called “functional” or “hard” chromium and is usually applied directly to the basis metal and is usually thicker than decorative deposits. 1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.3 This guide is not intended as a standardized procedure, but as a guide for obtaining smooth, adherent coatings of chromium of a desired thickness while retaining the required physical and mechanical properties of the base metals. Specified chromium electrodeposits on ferrous surfaces are defined in Specification B650. 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 appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.5 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.