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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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.
A38 occurring conditions such air or aerated water will do this and so under many exposure conditions stainless steels will naturally self-passivate.
Passivation treatments are sometimes specified, but it is important to consider whether this is strictly necessary or not.
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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.
Citric acid treatments can also be considered as an alternative to nitric acid as both provide the oxidising conditions necessary for passivation. Citric acid is a less hazardous method and has environmental benefits in terms of ‘NOx’ fume emission and waste acid disposal.
Article: Passivation of stainless steels
This standard covers both nitric and citric acid treatments. In addition, this standard also includes citric acid treatments. Parts treated however must pass specific tests to confirm the effectiveness of the passivation, although in practice the tests are for a80 detection of the effects of residual iron contamination aastm the surface of the parts. Unlike ASTM A, the standard does not require specific solutions for particular stainless steel grades or types, although 3 specific treatments are identified.
The standard notes that the high carbon martensitic stainless steels, such as C, are not suitable for acid passivation as they can be attacked or be subject to hydrogen embrittlement. The standard also allows any combination of citric acid concentration, temperature and time, provided that the passivation test criteria can be met.
Specific treatments are however also specified. The treatments are then defined by the process classes. In the case of classes C3 and C4, a two step process is defined, with a clean water rinse between the two steps, shown in the table below. Office and Postal Address: 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.
ASTM A Passivation Standard | Able Electropolishing
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.
Citric acid passivation as an alternative to nitric acid treatments Citric acid treatments can also 999 considered as an alternative to nitric acid as both provide the oxidising conditions necessary for passivation. Specifications for passivation treatments for stainless steels Traditionally the American standards have been used.
Process Class Stainless Steel Types C1 or C2 Austenitics, austenitic precipitation hardening and duplex C3 High chromium martensitics C4 Ferritics, martensitics and martensitic precipitation hardening. Range C Time mins.
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