ISO 8044:2020 pdf free.Corrosion of metals and alloys一Vocabulary.
Note 1 to entry: The unit used to express the corrosion rate depends on the technical system and on the type of corrosion effect. Thus, corrosion rate is typically expressed as an increase in corrosion depth (3.11) per unit time, or the mass of metal turned into corrosion products (3.8) per area of surface and per unit time, etc. The corrosion effect may vary with time and may not be the same at all points of the corroding surface. Therefore, reports of corrosion rates are typically accompanied by information on the type, time dependency and location of the corrosion effect.
Note 1 to entry: The threshold stress intensity factor is a concept of linear elastic fracture mechanics (LEFM) and is applicable when the plastic zone size is large compared with the microstructure, the crack is sufficiently long, and a high constraint to plastic deformation prevails, i.e. under plane strain predominant conditions. For growing stress corrosion cracks, LEFM is not necessarily applicable in all detail but is adopted as a pragmatic tool that is commonly used. Note 2 to entry: Stress corrosion cracks may initiate at a surface or a surface defect and grow in the“small crack” regime at stress intensity factor levels below the apparent threshold stress intensity factor. Therefore, LEFM is
not applicable in the“small crack” regime. cracking that results from the presence of hydrogen in a metal and tensile stress [residual or applied or both) Note 1 to entry: HSC describes cracking in metals that are not sensitive to sulfide stress corrosion cracking (SSCC) (4.43) but which may be embrittled by hydrogen when galvanically coupled, as the cathode (7.1.3), to another metal that is corroding actively as an anode (7.1.4). The term “galvanically induced HSC” has been used for this
mechanism of cracking. irradiation-assisted stress corrosion cracking intergranular cracking of austenitic stainless steels resulting from a reduction in the chromium concentration in a very narrow band at the grain boundaries following exposure to high neutron irradiation doses exceeding one displacement per atom, which causes the migration of point defects to the grain boundaries
stepwise cracking SWC cracking that connects hydrogen-induced cracking (HIC] (4.39) on adjacent planes in a metal Note 1 to entry: This term describes the crack appearance. The linking of hydrogen-induced cracks to produce stepwise cracking is dependent upon local strain between the cracks and embrittlement of the surrounding steel by dissolved hydrogen. HIC/SWC is usually associated with low-strength plate steels used in the production of pipes and vessels.exfoliation corrosion stratified form of subsurface stress corrosion (4.30) of susceptible primary wrought alloy mill products having a highly directional grain structure, accompanied by detachment of separate layers from the body of the material, formation of cracks and finally usually complete layer-by-layer disintegration of metal Note 1 to entry: Exfoliation generally proceeds along grain boundaries, but with certain alloys and tempering it may develop along transgranular paths or a mixed intergranular/transgranular path. Note 2 to entry: Layer corrosion can be developed on the first stage.outdoor accelerated corrosion test (6.5) by intermittent spraying test specimens or objects with a spray of sodium chloride solution Note 1 to entry: The method is suitable for specimens and objects of metals with or without coating. Note 2 to entry: The name “scab” is an acronym of simulated corrosion atmospheric breakdown. ISO 8044 pdf download.