1 This practice is under the jurisdiction of ASTM Committee A01 on Steel, Last previous edition approved in as A – 99 (). May 2nd, – Below is a technical summary of specification ASTM A 99 Advanced Plating Technologies is not. Gold plating is an exceptional finish for. BOOK ID: ECUadPJ && Download Book Pdf Astm A Finish Free. Passivation Services â€“ Welcome to Scott Metal Finishing. ASTM A 99 Advanced.
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The standard notes that the high carbon martensitic stainless steels, such as C, are not suitable for acid ast as they can be attacked or be subject to hydrogen embrittlement.
Article: Passivation of stainless steels
In the case of classes C3 a80 C4, a two step process is defined, with a clean water rinse between the two steps, shown in the table below. Parts treated however must pass specific tests to confirm the effectiveness of the passivation, although in practice the tests are for the detection of the effects of residual iron contamination on the surface of the parts.
Meaningful tests to establish the degree of cleanness of a surface are few, and those are often difficult to administer and to evaluate objectively. 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.
Methods are described for the detection of free iron and transparent chemical and oily deposits. The degree of cleanness required on a surface depends on the application. Stainless steels cannot be passivated unless the steel surface is clean and free from contamination and scale from welding operations.
Nitric acid alone can be used to remove light surface iron contamination after which the acid facilitates the passivation of the cleaned steel surface. Naturally occurring conditions such air or aerated water will do this and so under many exposure conditions stainless steels will naturally self-passivate. While the practice provides recommendations and information concerning the use of acids and other cleaning and descaling agents, it cannot encompass detailed cleaning procedures for specific types of equipment or installations.
The treatments are then defined by the process classes. Such chemical treatment is generally not necessary for the formation of the passive film. Some of the various meanings associated with the term passivation that are in common usage include the following:.
Passivation of stainless steels Introduction Stainless steels are designed to naturally self-passivate whenever a clean surface is exposed to an environment that can provide enough oxygen to form the chromium rich oxide surface layer, on which the corrosion resistance of these alloys depends.
Others, such as food-handling, pharmaceutical, aerospace, and certain nuclear applications, may require extremely high levels of cleanness, including a3800 of all detectable residual chemical films and contaminants that are invisible to ordinary inspection methods. Specifications for passivation treatments for stainless steels Traditionally the American standards have been used. Unlike ASTM A, the standard does not require specific solutions for particular stainless steel grades or types, although 3 specific treatments are identified.
In addition, this standard also includes citric acid treatments. For more specific safety precautions see 7. Link to Active This link will always route to the current Active version of the standard.
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In some cases, no more than degreasing or removal of gross contamination is necessary. Citric acid passivation atm an alternative to nitric acid treatments Citric acid treatments can also be considered as an alternative to nitric acid as both provide the oxidising conditions necessary for passivation. It was at one time considered that an oxidizing treatment was necessary a830 establish this passive film, but it is now accepted that this film will form spontaneously in an oxygen-containing environment providing that the surface has been thoroughly cleaned or descaled.
These recommendations are presented as procedures for guidance when it is recognized that for a particular service it is desired to remove surface contaminants that may impair the normal corrosion resistance, or result in the later contamination of the particular stainless steel grade, or cause product contamination.
Citric acid is a less hazardous method and has environmental benefits in terms of ‘NOx’ fume emission and waste acid disposal.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. Office and Postal Address: It therefore in no way precludes the necessity for careful planning and judgment in the selection and implementation of such procedures.
ASTM A380 Passivation Standard
Process Class Stainless Steel Ast C1 or C2 Austenitics, austenitic precipitation hardening and duplex C3 High chromium martensitics C4 Ferritics, martensitics and adtm precipitation hardening. This standard covers both nitric and citric acid treatments. On the other hand, some of the practices may be applicable for these purposes.
Citric acid treatments can also be considered as an alternative to nitric acid as both provide the oxidising conditions necessary for passivation. Range C Time mins. The term “iron,” when hereinafter referred to as a surface contaminant, shall denote free iron.
Unless otherwise specified, it is this definition of passivation that is taken as the meaning of a specified requirement for passivation.
The standard also allows any combination of citric acid concentration, temperature and time, provided that the passivation test criteria can be met. Pickling, passivation and removing iron contamination with nitric acid Passivation treatments are sometimes specified, but it is important to consider whether this is strictly necessary or not.
Related Links Xstm of Passivating Products. Specific treatments are however also specified.