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.
|Published (Last):||18 July 2006|
|PDF File Size:||4.63 Mb|
|ePub File Size:||20.17 Mb|
|Price:||Free* [*Free Regsitration Required]|
Unlike ASTM A, the standard does not require specific solutions for particular stainless steel grades or types, although 3 specific treatments are identified.
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 stainless steel then is rapidly cooled through the temperature range of 1, and degrees F, or and degrees C to inhibit carbide precipitation, and then at lower temperatures exposed to air, where the protective oxide film forms spontaneously.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. Most Popular Content This Week Fabrication, additive manufacturing companies produce part for airliner Solving the skills gap one class at a time Top 5 in —Articles about waterjet cutting 3D scanning—The first step in making a dream come to fruition SLM Solutions white paper: Specifications for passivation treatments for stainless steels Traditionally the American standards have been used.
The most commonly used of these is the copper sulfate test, in which a sulfuric acid-copper sulfate solution is swabbed on the surface for six a3380-99. On the other hand, ASTM A also notes that “Passivation is removal of exogenous or free iron or iron compounds from the surface of a stainless steel by chemical ashm, most typically by a treatment with an acid solution that will remove the surface contamination but will not significantly affect the stainless steel itself.
These recommendations are presented a380-999 procedures for guidance when it is recognized that for a particular service a380-9 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. 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.
Keeping stainless steels stainless
It was at one time considered that an oxidizing treatment was necessary to 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.
Bright annealing entails heating a38099 stainless steel to a suitably high temperature usually more than 1, degrees F, or 1, degrees C in a reducing atmosphere such as dry hydrogen gas.
An example of reduced corrosion resistance is shown in Figure 1. Today, it remains the only North American publication devoted to this industry and it has become the axtm trusted source of information for tube and pipe professionals. However, some confusion still exists about the definition of passivation and what really causes a passive film to form on the surface of stainless steel.
In some cases, no more than degreasing or removal of gross contamination is necessary. Nitric acid alone can be used to remove light surface iron contamination after which the acid facilitates the passivation of the cleaned steel surface.
Article: Passivation of stainless steels
The color of this film is a function of the film thickness that developed at various distances from the weld. Figure 1 Asfm 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. Link to Active This link will always route to the current Active version of the standard.
Under these conditions, the surface is passive, or resistant to corrosion. This process is described in a general way in 6.
ASTM A Passivation Standard | Able Electropolishing
Die fully sensored and still getting miss-hits? 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: On one hand, ASTM A notes asm “Passivation is a process by which a stainless steel will spontaneously form a chemically inactive surface when exposed to air or other oxygen-containing environments.
Stainless steel owes its corrosion resistance to its ready oxidation to form this protective film; however, stainless steel’s exposure to an oxidizing environment at higher temperatures or to a more highly oxidizing environment at a given temperature will result in the formation a38-099 an oxide heat tint of increasing thickness, ranging in color from asym light straw to a dark black.
Typical chemical treatment involves exposing the stainless steel surface to an oxidizing acid solution in which the significant variables are time, temperature, and concentration.
While it is essential that surface contamination be removed completely, it is the latter interpretation of passivation that relates to establishing the corrosion resistance of stainless steels. Meaningful tests to establish the degree of cleanness of a surface are few, and those are often difficult to administer and to evaluate objectively. 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.
More Content by Carl R. When the section was placed in service, a corrosive environment preferentially attacked the stainless steel surface under the heat tint.
Stainless steel’s corrosion resistance is due to a thin, chromium-rich, transparent oxide film on the surface 1. In many instances of passivation failure, or corrosion attack, the integrity of the passive oxide film is compromised by the concentration of halide ions, for example, chlorine, which chemically attacks the oxide film.
In order to avoid ambiguity in the setting of requirements, it may be necessary for the purchaser to define sstm the intended meaning of passivation. Unless otherwise specified, it is this definition of passivation that is taken as the meaning of a specified requirement for passivation. 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.
Stainless steels cannot be passivated unless the ashm surface is clean and ashm from contamination and scale from welding operations.