1 This practice is under the jurisdiction of ASTM Committee A01 on Steel, Last previous edition approved in as A – 99 (). Standard. Standard number, ASTM-A ; ASTM-A Title, Standard Practice for Cleaning, Descaling, and Passivation of Stainless. May 2nd, – Below is a technical summary of specification ASTM A 99 Advanced Plating Technologies is not. Gold plating is an exceptional finish for.
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When the section was placed in service, a corrosive environment preferentially attacked the stainless steel surface under the heat tint.
On the other hand, some of the practices may be applicable for these purposes. In order to avoid ambiguity in the setting of requirements, it may be necessary for the purchaser to define precisely the intended meaning of passivation.
The term “iron,” when hereinafter referred to as a surface contaminant, shall denote free iron. Others, such as food-handling, pharmaceutical, aerospace, and certain nuclear applications, may require extremely high levels of cleanness, including removal of all detectable residual chemical films and contaminants that are invisible to z380-99 inspection methods. This protective film develops when more than For certain exceptional applications, additional requirements which are not covered by this practice may be specified upon agreement between the manufacturer and the purchaser.
ASTM A Passivation Standard | Able Electropolishing
This film is about 10 atoms, or 35 angstroms, thick 0. Most Popular Content This Week Fabrication, additive manufacturing companies produce part for airliner Solving the skills gap one class at a asrm Top 5 in —Articles about waterjet cutting 3D scanning—The first step in making a dream come to fruition SLM Solutions white paper: 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: You May Also Like. Best performance is achieved with a Cr-Fe ratio of the surface oxide of more than 1. 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 ast, of residual iron contamination on the surface of the parts. Evidence of in-service pitting in the heat tint aastm the HAZ may be seen in Figure 2.
Stainless steels cannot be passivated unless the steel surface is clean and free from contamination and scale from welding operations. Passivation results in the formation a3800-99 an oxide film having a higher chromium-to-iron ratio than the underlying stainless steel because of the preferential oxidation of chromium and the a380-9 dissolution of iron.
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.
Related Links Suppliers of Passivating Products. Today, it remains the only North American publication devoted to this industry and it has become the most trusted source of information for tube and pipe professionals.
Some of the various astj associated with the term passivation that are in common usage include the following: While very effective as a passivator, this solution may have environmental ramifications. The degree of cleanness required on a surface depends on the application.
EDTA is a chelating agent that keeps iron in solution over a wide pH range. 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.
Extreme chloride concentrations may develop because of evaporation ast, systems that are not properly drained, ast, negates the corrosion protection expected of stainless steels.
ASTM A sets forth several techniques to determine the presence of free iron a measure of adequate passivation on the surface of stainless steel.
In many instances of passivation failure, or corrosion attack, the integrity of the passive oxide film is compromised by the concentration of halide axtm, for example, chlorine, which chemically attacks the oxide film.
Keeping stainless steels stainless
Although they apply primarily to materials in the composition ranges of the austenitic, ferritic, and martensitic stainless steels, the practices described may also be useful for cleaning other metals if due consideration is given to corrosion and possible metallurgical effects. Passivation typically is accomplished either through an appropriate bright annealing of the stainless steel or by subjecting the surface to an appropriate chemical treatment. It was at one time considered that an oxidizing treatment was necessary to establish this passive film, but zstm is now accepted that this film will form spontaneously in an oxygen-containing environment providing that the surface astmm been thoroughly cleaned or descaled.
It is likely that the darker, thicker oxide tints are the result of the formation of an oxide with higher iron and magnesium content; that is, reduced chromium content. Figure 1 This interior view of a weld made on L exhibits the formation of heat tint on the weld and HAZ caused by the presence of oxygen during orbital welding. In addition, visual inspection of internal surfaces is often impossible because of the configuration of the item.
Keeping stainless steels stainless – The Fabricator
Preservation of the passive film requires the presence of oxygen in the environment to which the stainless steel is exposed. In the interior of an orbitally welded section of L, the inner surface of the weld bead, and the adjacent HAZ, are covered with a varicolored oxide film, or heat tint. Light oxides can be removed with bright annealing when possible; light tints and iron contamination may be cleaned with citric acid solutions; darker tints may require cleaning with various pickling pastes; while heavier, darker oxide films will require pickling solutions.
The treatments are then defined by the process classes. Many combinations of these variables can be used, but two of the most common are:. Kuxhaus of MK Services Inc.
ASTM A380 Passivation Standard
The color of this film is a function of aatm film thickness that developed at various distances from the weld. Methods are described for the detection of free iron and transparent chemical and oily deposits. Once the surface is cleaned and the bulk composition of the stainless steel is exposed to air or an oxygen-containing chemical environment, the passive film forms immediately.